The present invention relates to a utility support framing system and method of use for structurally suspended concrete slabs of slab-on-voidform foundations. The inventive utility support framing system and method of use isolates utilities, hanger assemblies, and framing system components from soil so as to avoid problems created by volumetric soil changes which otherwise would damage utility lines under foundation systems. The inventive utility support framing system permits suspending utility pipes under a slab of a slab-on-voidform foundation while avoiding the problems of the prior art. The invention also relates to a novel mountable pipe clamp and method of use and a novel protective utility counterweight and method of use for transitioning a utility system from a suspended condition to a soil supported condition.

Problems due to expansive soils have been reported in many countries all around the world. Every year they cause millions of dollars in repair costs due to their severe damage to structures. Expansive soils often contain clay minerals such as bentonite, montmorillonite, and smectite that have the potential to expand and shrink significantly due to changes in moisture content. The expansive potential of the clay is greater near the ground surface where the profile is subjected to seasonal and environmental changes in moisture content and has less soil overburden pressure, from soil above, to counteract expansion. Increasing the moisture content of the clay often causes dramatic increases in volume, especially near the ground surface where the ground surface can rise up to 18 inches or more in some areas, with an estimated 6 inches of potential upward movement being common in many urban areas where highly expansive soils are present. Similarly, decreasing the moisture content of the clay often causes dramatic decreases in volume, especially near the ground surface where the ground elevation can drop in elevation as much as it is rises when the clay gets wet. Fissures in the soil can develop during periods of time when the clay dries out due to seasonal variations in rain, growth of trees, or other sources. These fissures often allow water to penetrate to deeper layers when water is present. This often produces a cycle of shrinkage and swelling that causes the soil to undergo progressively greater amounts of volumetric changes over time. This movement in the soil often results in damage to buildings, especially in lightweight infrastructure such as sidewalks, driveways, basement floors, pipelines and shallow foundations that are not isolated from the volumetric changes and do not have sufficient weight and/or stiffness to resist the changes in stress caused by the volumetric changes in the soil.
The depth at which expansive soils can cause damage is also significant. As noted the 2014 Senior Thesis titled "An Examination of Changes within the Active Zone Moisture Content and Soil Swell Potential of Expansive Clay Soils at a Site in Denton County, Texas" by Marc William Cappell with Oklahoma State University, "Deep-seated swell is the additional upward soil swell movement that could result from moisture changes and soil swelling below a typical 10 foot (305 cm) deep active-zone (Farrow and Roland 2005)." As noted in a paper by Nelson, Overton and Durkee, all from Colorado, that was published for the Shallow Foundation and Soil Properties Committee Sessions at the 2001 American Society of Civil Engineers (ASCE) Civil Engineering Conference, titled "Depth of Wetting and the Active Zone," "The term "active zone" generally refers to the zone of soil that either is contributing to or has the potential to produce heave." The 2001 paper describes how, for any specific soil profile with expansive clay, there is a "Depth of Potential Heave" at "which the overburden vertical stress," from the weight of the soil above, "equals or exceeds the swelling pressure of the soil," with the "swelling pressure" being the pressure required to prevent swelling. As noted in the Discussion and Conclusions of the 2001 paper, "There is no sound rationale behind assuming that the depth of wetting will stop at some assumed depth. Instead, a more prudent assumption is to assume that, in time, the depth of wetting will extend throughout the entire depth of potential heave. This in fact, is realistic and conservative." Therefore, for the purposes of this application, the term "active zone" will refer to the region of soil from the ground surface down to the depth of potential heave.
There are other types of soil conditions which can cause changes in volume similar to expansive soil. These other soil conditions can include without limitation: frost heave in colder climates where water in the soil seasonally expands as it freezes and then contracts as it melts; settlement in under-consolidated clay soil cases due to poor water pressure dissipation over long periods of time after a construction project increases the overburden pressure such as by adding soil to raise the ground elevation to a desired finish floor elevation; and, collapsible soils cases in which a small reduction in moisture content of some sand configurations with relatively low densities can cause an immediate and dramatic reduction in soil volume. While the focus of this disclosure primarily discusses protection of under-slab utilities from expansive clay soils, the same comments often apply to these other soil conditions which can be equally challenging in areas of the country where expansive clay soils are not present.
Most buildings require one or more utility lines to, for example, provide clean water and remove wastewater with a plumbing system. Utility lines buried in the ground and in contact with expansive soil are subject to stresses from expansive soil. Domestic water pipes are plumbing lines that provide clean water by a pressurized water line. Fire protection pipes are plumbing lines that provide water for automatic fire sprinkler lines by a pressurized water line. A significant amount of water damage often occurs when pressurized water lines break due to expansive soil damage. And, often the stresses from expansive soil are great enough to break these pipes. Expansive soil can push plumbing lines up through the slab, damaging plumbing fixtures and even causing damage to walls. When utilities transporting water in any form leak, especially pressurized water lines, the leaks can cause excessive saturation under a foundation. This saturation often leads to further soil expansion which often causes even greater damage to the foundation and superstructure. Sanitary sewer pipes are plumbing lines that transport wastewater away from plumbing fixtures such as toilets and sinks by gravity, requiring that the lines slope downward to the exterior of the building with sufficient slope. When expansive soil movement causes sanitary sewer lines to shift so that they no longer slope as intended, solids in wastewater often stop in the plumbing and this causes sewage to build up and obstruct the plumbing, which becomes a health, safety and welfare problem for the occupants.
Several techniques have been used in the past to solve problems caused by the swelling and shrinking of expansive soils. Section 1808.6 of the 2021 International Building Code (IBC) provides design requirements for foundations on expansive soil using many older techniques in the prior art. These requirements do not address under-slab utilities but in certain cases they can reduce or even prevent damage to under-slab utilities from volumetric soil changes.
2021 IBC Section 1808.6.3 allows expansive soil to simply be " . . . removed to a depth sufficient to ensure a constant moisture content in the remaining soil," which can protect under-slab utilities if all of the expansive soil is removed to expose dimensionally stable material, such as limestone, if dimensionally stable material happens to exist naturally near the ground surface. However, where such favorable conditions do not exist, the depth of excavation required would often exceed 10 feet below the ground surface. As noted above, there is no sound rationale behind assuming that the depth of wetting will stop at some assumed depth, and the prudent approach is to assume the depth of wetting can occur over the full depth of potential heave. Consequently, a disadvantage of the approach of removing the expansive soil to a sufficient depth, and the reason this approach is often not selected by design professionals in many areas, is that the depth required to sufficiently address the problems associated with expansive soils is not practical and/or more expensive than other options in the prior art. An example of this approach being impractical and/or expensive is when constructing an addition to an existing building and such an operation could undermine the existing foundation. Another example of this approach being impractical and/or expensive is when constructing a new building in a densely populated urban area where the property line is at near the perimeter of the foundation so it does not allow a sufficiently deep vertical retaining wall to be erected without permission of the adjacent property owner, which is often a municipality that uses the adjacent land for a road where they are not inclined to allow disturbing their property. Another disadvantage of this approach is that installing dimensionally stable material such as crushed limestone rock (often called "flex base" and used for road construction) is often more expensive to purchase in areas where expansive clay soils are predominant than other types of fill that cost less but are not as dimensionally stable, such as "select fill" consisting of soil with less expansive properties than the original soil in the ground. If select fill is used in relatively shallow depths, such as a few feet, many geotechnical engineers have found the level of damage to structures associated with the use of the less-desirable material to be tolerated; however, when depths greater than 10 feet are required, many geotechnical engineers have concerns with the cumulative effect of the volumetric changes that can occur in even select fill such as expansive soil swelling and shrinking as well as settlement. Even when rock is encountered, many areas of the county have naturally occurring layers of expansive soil and rock layers alternating, sometimes with high variability over a single building footprint. The intermittent layers of rock can make excavation of the expansive soils to a sufficient depth highly problematic, especially where there are large rock boulders that can be greater than the size of a school bus and much harder than concrete, causing unpredictably long delays in construction when they are encountered. In cases where the slab is placed on the ground after removing expansive soil to a sufficient depth and replacing it with dimensionally-stable material, under-slab plumbing is typically buried in the dimensionally-stable material. However, all of the challenges noted above in removing and replacing expansive soil under slabs are the same challenges in removing and replacing expansive soil under the utilities under those slabs. Therefore, in areas where expansive soil exists without a layer of competent bedrock that is encountered within a few feet of the ground surface and that extends well below 10 feet under the ground surface, the approach of simply removing expansive soil to protect under-slab plumbing is often not possible, not effective, not practical, time-consuming, and/or more expensive than other options in the prior art.
2021 IBC Section 1808.6.3 also allows expansive soil to be " . . . stabilized by chemical, dewatering, presaturation or equivalent techniques."
Presaturation is still commonly used today in many areas, with the theory that pre-swelling the soil will reduce or eliminate the potential heave. This theory is based on an assumption, though, that the moisture will not leave the clay subgrade and cause damage from soil shrinkage; however, this assumption has proven to be false in many cases where long periods of drought and/or tree roots dry out the subgrade under buildings and cause damage to foundations and under-slab utilities.
Dewatering is the opposite of presaturation and is a less common approach to reduce the potential vertical movement of expansive soil because, while in theory this may reduce the shrinkage, many people recognize that if water is introduced to dewatered soil, the soil will swell.
In laboratories, companies that claim to be able to stabilize expansive soil with proprietary techniques often produce laboratory evidence that they can reduce the volumetric changes of soil. These manufacturers do not typically claim to reduce all of the potential volumetric changes of the soil, but rather claim to be able to reduce it to a level where they believe the level of damage to a facility is tolerable. A paper by Petry and Little in the November/December 2002 edition of the Journal of Materials in Civil Engineering, titled "Review of Stabilization of Clays and Expansive Soils in Pavements and Lightly Loaded Structures—History, Practice, and Future" addresses some of the challenges with stabilization techniques and states, "It is always important and will continue to be important to clearly identify the mechanisms of modification and stabilization of clay soils. Only when these have been clearly identified can we address problematic reactions and improve the product." The paper further states, "Although some nontraditional stabilizers are attractive alternatives, some of their producers are overly aggressive in promoting their product. Some of these promotions attack traditional stabilizers in an attempt to discredit them and obtain market share. These attacks often demonstrate a poor level of understanding of the mechanisms involved." And, the paper in summary states, "The paper warns that competent engineers who apply their professional knowledge judiciously must judge the effectiveness and appropriateness of all stabilizers. This knowledge is not cheap but must be gained through a dedicated effort to learn the fundamental concepts of stabilization and to keep abreast of the state of knowledge as it develops nationally and in a given region. This requires dedication to continuing education and a proactive mindset in attitude by the engineer." These comments speak to the difficulty in selecting a proprietary stabilization technique and knowing with confidence that it will be successful. And, again, while some claim to come very close, it is important to remember that these techniques do not completely eliminate any possible soil volume change. An added concern with chemical stabilization techniques can be concerns regarding potentially hazardous chemicals being introduced into the ground.
The prior art also teaches the controlling the moisture content of expansive soil under a foundation. For example, U.S. Pat. No. 4,534,143, issued to Goines et al., discloses a subsurface irrigation system causing water to slowly percolate into the expansive soil supporting a foundation so as to maintain the moisture content of the soil. However, it is virtually impossible for any artificial means of moisture control to maintain absolutely constant moisture contents under a real facility exposed to the highly variable conditions which are common. Moisture migration n partially saturated soil is extremely complex and the mechanisms are only generally understood by limited empirical evidence that supports widely varying theories. What little evidence there is relative to the complexity of the phenomenon actually indicates that moisture migration can occur even if there was a vertical barrier to any moisture migration in or out under the perimeter edge of a foundation, making any attempt at complete moisture control potentially ineffective, with any interior moisture migration as soil conditions reach an equilibrium over time causing volumetric changes considering that in almost all cases on real project there are non-homogenous soil conditions under a building, especially so as the moisture content of soil itself is a common non-homogenous soil condition. U.S. Pat. No. 4,015,432, issued to Ball, discloses a foundation structure supported on expansive soil moistened to its plastic limit. Through a moisture controlling barrier placed around the foundation periphery, moisture can be added in an attempt to ensure that the moisture content of the soil remains at its plastic limit. However, a moisture controlling barrier cannot be reliably effective in all cases as described above. Furthermore, it is only effective even in theory if it is deep enough, and the depth required in some instances, as discussed above considering the depth of the active zone, can be more expensive to construct than other approaches which are more likely to be successful that do not require such a deep excavation. [00014] 2021 IBC Section 1806.6.2 allows foundations to be designed as a slab-on-ground foundation, where the entire bottom surface of the foundation, including the slab, is generally supported vertically by the soil. In general, when this approach is taken, any significant concerns with the potential magnitude of damage from volumetric changes in expansive soil are typically addressed in part by attempting to lessen the anticipated level of damage by applying the techniques described above as referenced in 2021 IBC Sections 1808.6.3 and 1808.6.4, and the challenges with those approaches are discussed above. In addition, a primary challenge with installing a slab-on-ground foundation over expansive soils that are not completely removed or completely stabilized is that some level of damage due to expansive soil should be expected. 2021 IBC Section 1806.6.2 refers to design methods that attempt to account for soil-structure interaction, the deformed shape of the soil support as well as center lift and edge lift conditions, all of which note how a foundation will distort in three-dimensional geometry and an attempt is made to limit the distortion to an acceptable level. This is a common approach, especially for residences and small commercial structures built in geographic areas where expansive soils are prevalent, however, damage occurs to both the superstructure and often the under-slab utilities regularly in these types of facilities. Evidence of this is the large number of foundation repair companies that are prevalent in geographic areas where expansive soils are common. If damage occurs to an under-slab utility, the slab can be sawcut and removed immediately above the area of broken utility so that the utility can be repaired and the slab repaired; however, damage to under-slab utilities can and often does occur, requiring expensive repairs.
2021 IBC Section 1808.6.1 provides an alternate to a slab-on-ground foundation by permitting foundations be designed to resist differential volume changes and prevent structural damage to the supported structure. With this alternative approach, "Foundations penetrating expansive soils shall be designed to resist forces exerted on the foundation due to soil volume changes or shall be isolated from the expansive soil."
An older method in the prior art that meets the requirements of 2021 IBC Section 1808.6.1 is to install an elevated foundation with a traditional crawlspace under the floor. When a properly designed crawlspace foundation resists expansive soil forces, the superstructure being elevated by a crawlspace protects the superstructure from expansive soil damage if the height of the crawlspace is greater than the magnitude of the potential vertical upward movement due to volumetric changes of expansive soils. There are two primary plumbing codes used in the United States today: the International Plumbing Code and the Uniform Plumbing Code. Neither of the latest published versions of either code explicitly require isolation of plumbing from expansive soils. And, where under-slab utilities are supported by and buried in an expansive soil material, volumetric soil changes can cause damage to the under-slab utilities, especially where the floor structure is isolated and the differential movement is greater than if the slab was a slab on grade foundation. If under-slab utilities are hung from an elevated floor structure after the elevated floor structure is installed, the under-slab utilities being elevated above an under-utility space protects the under-slab utility from expansive soil damage if the under-utility space is greater than the magnitude of the potential vertical upward movement due to volumetric changes of expansive soils. And, this post-slab isolation approach is actually common in portions of crawlspace foundations where access is provided to the under-floor space after the floor structure is installed by means of an access opening, but this post-slab isolation approach is not typically applied to areas under a slab where the depth of under-slab utilities is deeper than the subgrade of a crawlspace. Many building codes require that underfloor spaces with access openings be considered crawlspaces and be ventilated for the safety of those that enter an under-floor space, either with an unpowered natural ventilation system comprised of sufficiently large openings in appropriate locations or with a mechanical ventilation system. However, a disadvantage of the natural ventilation system is that animals such as snakes, opossums, cats, rats, mice, spiders, termites, bees, . . . etc. can often find access to the under-floor space and create safety hazards for the occupants when they leave the building and an ongoing nuisance for maintenance staff to address these safety hazards. Furthermore, water and/or humidity can often enter through natural ventilation openings and the prescriptively designed natural ventilation openings are sometimes not sufficient to be capable of removing the water and/or humidity, which can create problems with corrosion of structural members, as well as potentially smells and/or fungal growth that can find its way through openings in the slab and create health, safety and welfare concerns. Mechanically ventilated systems are problematic for owners because they can have mechanical failures over time due to wear and tear on moving parts and exposure to the elements, and it is common for occupants and maintenance staff to not realize when these mechanical failures have occurred because occupants generally do not go into under-floor spaces unless there is an event creating a special need such as a maintenance activity. When mechanical ventilation systems stop functioning and there is not a natural ventilation system in place, the problems with moisture accumulation can occur such as corrosion to structural elements that causes safety concerns and mold and smells that enter the occupied space above the floor structure, which can all be dramatic where steel floor structures are used that are not sufficiently protected from corrosion, such as with ungalvanized steel, and when openings such as floor hatches do not have robust and properly functioning seals.
A more recent alternative to a crawlspace type of foundation is the slab-on-voidform foundation type. An advantage of the slab-on-voidform system is that it can cost significantly less to construct than a crawlspace foundation. One reason a slab-on-voidform foundation can cost significantly less is because the floor structure does not require expensive formwork, often regularly spaced unshored steel beams, to span long distances and hold up fresh concrete that has no compressive strength while not deflecting an unacceptable amount. Another reason a slab-on-voidform foundation can cost significantly less is because the height of the under-floor space of a slab-on-voidform foundation needs only to be enough to accommodate the potential vertical movement of expansive soil whereas the height of the under-floor space of a crawlspace foundation must be adequate to meet building code requirements for access and allow workers to do work such as removing any temporary shoring, installing any under-slab utilities that will be installed after a floor structure is in place, as well as inspecting conditions after occupancy and eventually doing repairs; and, the cost of a foundation increases as the height of the gradebeams around perimeter increase due to increases in the height of an under-floor space. And, another reason why the slab-on-voidform system can cost less to construct is that a slab-on-voidform system typically does not have an under-slab drainage system since the under-floor space is not accessible whereas crawlspace foundations typically have a drainage system. And, another reason why the slab-on-voidform system can cost less to construct is that a slab-on-voidform system typically does not have any lighting like is common in many crawlspaces because the under-floor space of a slab-on-voidform foundation is not an accessible space. Another reason why the slab-on-voidform system is preferred over a crawlspace system is that a slab-on-voidform foundation can be installed at the ground level surrounding a building without requiring stairs to raise a floor elevation so as to provide natural ventilation of a crawlspace, if such a system is used. Another reason why the slab-on-voidform system is preferred over a crawlspace is that there is not natural ventilation or mechanical ventilation as described above for crawlspace foundations, and consequently no challenges associated with those systems as described above, as there are with crawlspace foundations. While the slab-on-voidform foundation type is a more recent application than a crawlspace foundation type, slabs with various types of voids that could possibly be considered slab-on-voidform foundations have been installed for over a century. With time, the slab-on-voidform foundation type has evolved and a common manifestation is where drilled piers and grade beams are installed that resist the forces of expansive soil, then a layer of degradable carton voidforms are installed over a subgrade and the voidform system often includes a layer of Masonite at the top, then a vapor barrier such as a plastic sheet is installed over the voidforms, and then slab reinforcement is installed, and then concrete is poured to create the slab of a slab-on-voidform foundation in which the degradable carton voidforms deteriorate sufficiently that the slab is isolated from the expansive soil beneath the under-floor space. One manufacturer of carton voidforms has indicated that they distribute approximately 30 Million square feet of carton voidforms for this type of application every year for new construction in North America. Because there is no means of access to the under-floor space as with a crawlspace foundation, under-slab utilities have historically been supported by and buried in expansive soil when a slab-on-voidform system is used, which can cause damage like has been described above in expansive soil conditions. It is true that moisture can accumulate in an under-floor space of a slab-on-voidform system; however, today many slabs are installed over vapor barriers with tape that adhere to the concrete at the edges of vapor barrier sheets and penetrations to prevent moisture from rising above the vapor barrier in modern slab-on-voidform foundations. Studies have shown that, if there is not a vapor barrier under carton voidforms, a subgrade typically has enough moisture with the moisture associated with fresh concrete as it cures, to cause modem carton voidforms to degrade in an acceptably fast time, several months for example, to lose enough strength that they will crush before telegraphing any loads up from a heaving subgrade, as they are typically not wax impregnated today as in some decades past. A paper by David K. Isbell, P E titled, Performance of Cardboard Carton Forms as presented on Feb. 21, 2001 to the Foundation Performance Association, and previously a part of a conference of the Texas Section of the American Society of Civil Engineers (ASCE) states, "The moisture from the subgrade plus the hydration of the concrete appear to provide adequate deterioration of the boxes." In some climates more than in others, degradable voidforms can be problematic if it rains too frequently or is too humid, because the degradable voidforms can lose their strength before concrete is poured and there have been many collapses of degradable voidforms when contractors have tried to take the risk rather than remove all of the reinforcement and voidforms and start all over again. Primarily for this reason, non-degradable voidform materials used in slab-on-voidform foundations are also in the prior art. In general, with voidforms that have non-degradable components, designers typically specify that they be installed in a manner so that they are capable of crushing under some theory of a crushing mechanism or that they are capable of cutting into a heaving soil under some theory in which the soil will swell in between the non-degradable components of a voidform system.
As an example of one of the more common systems of carton voidforms used today in many parts of the United States to provide temporary support for a slab of a slab-on-voidform foundation, VoidForm® Products, LLC provides a SureVoid® product corrugated paper voidform system with regularly spaced vertical cardboard partitions in a grid pattern with a horizontal layer of cardboard across the top and bottom. Typically, a layer of Masonite is placed over the carton boxes.
As another example of systems in the prior art for supporting slabs of slab-on-voidform foundations, Reliable Void Forms, of Austin, Tex., provides an alternative to the traditional carton void form system. Instead of corrugated paper, Reliable Void Forms uses a molded pulp form made of 100% recycled paper with a consistency and shape similar to an egg carton. Forms are produced in 61 cm×61 cm (24″×24″) squares with thicknesses of either 15 cm (6 in) or 20 cm (8 in). During installation, the forms can be cut, trimmed, or grinded to the appropriate shape and size. Unlike cardboard forms, the manufacturer claims these forms can be used in wet or dry conditions. Also, due to their shape and weight, they can easily be shipped, stored, hauled, and manipulated in the field. Once laid out on the site, the concrete is poured over the top. Gradually, over time, the forms will degrade, but until that happens, one theory purports that any soil expansion is isolated within the pockets.
An example of a voidform system with non-degradable components is a partially plastic voidform product by VoidForm® called StormVoid™ which has plastic elements that do not deteriorate like the standard carton SureVoid® products. This means the structural elements (i.e. slabs, grade beams, etc.) must be designed for the potential uplift pressures the form is capable of exerting.
Another example of a voidform system with non-degradable components in the prior are involves the use of a metal wire mesh formed into a volumetric shape as produced by SuperVoid Systems, LLC. In one theory, volumetric changes in the soil could cause the soil to push on the wire mesh, in turn causing the mesh to deform or the soil to push through the mesh. This means the structural elements (i.e. slabs, grade beams, etc.) must be designed for the potential uplift pressures the form is capable of exerting. If a version of the SuperVoid product is used with a horizontal layer of oriented strand board or plywood at the top of the wire mesh, the oriented strand board or plywood is degradable and can lose strength over time, but this is not problematic in and of itself when the SuperVoid system is used as a slab voidform because the slab will have cured by the time the wood material decays.
As there are many advantages with slab-on-voidform foundations, given that non-degradable voidforms can be used where degradable voidforms are not practical due to a wet climate, the primary disadvantage of the slab-on-voidform foundation type has been that there is no method available in the prior art of sufficiently protecting under-slab utilities from volumetric soil changes in a subgrade.
With regard to the protection of under-slab utilities under slab-on-voidform foundations, many slab-on-voidform foundations today are constructed with under-slab utilities being supported by and buried in a subgrade of expansive soil even though there is a known risk that volumetric soil changes could cause damage to a facility. The primary reason that under-slab utilities are still soil-supported is that a technology has not yet emerged in the prior art which provides complete isolation of the utilities from potential volumetric soil changes. Even if access to the under-floor space was provided, because the voidforms do not degrade quickly enough for workers to access an under-floor space without removing the voidforms or because non-degradable voidforms obstruct such access and would require removal, which would be an arduous task, the industry has not yet developed a method of construction with the necessary apparatuses so as to suspend under-slab utilities before a concrete slab of a slab-on-voidform foundation is poured. While there are some disagreements between designers on the relative merits of the theories applied when non-degradable voidforms are used to isolate slabs of a slab-on-voidform system, with regard to various specific types of non-degradable voidform systems, there is a general consensus among design professionals of all design disciplines that absolutely none of these systems are appropriate if non-degradable components of a voidform system can cause soil to impart forces, directly or indirectly through the non-degradable components.
Section 506.1 of the 2021 International Property Maintenance Code (IPMC), for example, requires where it is adopted locally that "Every plumbing stack, vent, waste and sewer line shall function properly and be kept free from obstructions, leaks and defects." And, for example, only a small amount of movement from volumetric soil change is all that it can take to cause a P-trap to crack just enough that the water in the P-trap spills out allowing noxious gases from a sanitary sewer system to enter an occupied space. There have been numerous lawsuits around the country that arise when plumbing is damaged from volumetric soil change soon after a building is occupied and under-slab utilities fail in various ways, especially when owners realize the magnitude of the cost required to repair the under-slab utilities as they can be required by building code to repair. The costs of repairs are so significant because, unlike with a slab on grade or a crawlspace, there is no convenient access to the under-slab utility locations needing repair. One reason it is so expensive to repair an under-slab utility under a slab of a slab-on-voidform foundation is that it is often required to sawcut temporary access openings in the slabs at the intersection of two lines with each line being approximately at the midpoint between a gridline of deep foundation elements such as drilled piers, then excavate by hand to dig laterally and find all locations where plumbing needs to be repaired, often having to walk wheelbarrows of dirt out of a building and dump it outside. If one were to sawcut immediately over any damaged utility location, sawcutting through a typical two-way structurally suspended reinforced concrete slab of a slab-on-voidform foundation, one could easily cause the slab to collapse as they sawcut through portions of the slab between piers that are necessary for structural stability and this does happen from time to time in the industry by accident when contractors think a slab is a slab on ground but find out too late that it is a slab-on-voidform system. Owners are even more angry when they find out that the repairs will not prevent the problem from happening over and over again, potentially, over the life of the facility. Designers in areas where expansive soil often discuss this primary disadvantage of a slab-on-voidform system with Owners before construction, noting that Owners could select a crawlspace option for additional cost if they want the ability to access and even to isolate some portions of the plumbing; however, most owners are unfortunately short-sighted in authorizing a slab-on-voidform system as they are focused on the short-term goal of trying to maximize the floor plan area for their facility's program with a given budget.
For example, in March 2021, the Geoprofessional Business Association (GBA) has published a case study, Case History Number 108, of a $25 Million damage claim made by an owner of a senior-living facility in Colorado in which slab-on-voidform construction was used where under-slab utilities were not sufficiently isolated from expansive soil that damaged the under-slab utilities. About four years after construction was completed and the building was occupied, sanitary sewers began backing up and a powerful stench was permeating the building and the walls and lower-level slab began to show heaving distress. The owner had to move residents out of the building and into suitable temporary housing and they eventually paid a contractor to excavate under the building and install a crawlspace.
As another example, in the United States Court of Federal Claims, Cause No. 09-672C, filed Sep. 7, 2012, which involves a case where under-slab utilities under a slab-on-voidform foundation were damaged by expansive soil because the under-slab utilities were not sufficiently isolated from the damage that expansive soil can cause, the court ruled that the mechanical engineering firm " . . . had a duty to isolate the plumbing from the expansive soil in a way that would accommodate the maximum potential soil heave predicted in the soils reports," noting that " . . . whether willful or not . . . " the mechanical engineering firm " . . . failed to heed the warning and guidance set forth . . . " " . . . in the soils reports' prediction that the soil could heave . . . " " . . . and provided a negligent design in violation of the Contract."
As early as 2007, the Foundation Performance Association (FPA) published a recommendation in their SC-11-0 publication titled Specification and Application of Void Spaces Below Concrete Foundations that "Expansive soils should not support under slab utilities below a Structural Slab" where the industry often refers to a slab of a slab-on-voidform foundation as a structural slab. The publication further states, "Under slab piping must remain stationary with respect to the slab. The distance between the slab and the buried utilities may change as the soil moisture changes. These changes could cause the utility lines to disconnect, start leaking or otherwise fail. There are various methods to accommodate such differential movement by using designs that allow the utilities to adjust to the changing conditions. The piping design beneath the foundation must take into consideration the differential movement between the interior stationary piping and the soil outside the foundation, and any associated bending stresses." The SC-11-0 publication even includes a diagram that diagrammatically shows a hanger assembly, including a traditional clevis hanger supporting an under-slab utility pipe, but the diagram shows the hanger to be either supported by rebar or to be supported by a concrete slab after it is poured and cured, both of which are impossible because the diagram shows both the slab and the rebar being supported by voidforms which are still intact which means that there is no access to install the utility pipe after the slab is poured and it means there was no support to install the utility pipe before the slab was poured. Additionally, the diagram does not show any means for retaining the soil on either side of a utility pipe. The discussion and diagram show the disconnect between what is desired and what limited technology was available in the prior art in 2007. In a 2014 revision to the SC-11 document, numbered SC-11-1, the FPA did not change any of the text cited but even with a revised detail they showed a scenario that is impossible to construct for reasons cited above. Their reference to "various methods to accommodate such differential movement by using designs that allow the utilities to adjust to the changing conditions" is referring to what some in the industry refer to as flexible joints, such as a flexible expansion joint. The FPA's recommendations have been made as a community of primarily geotechnical and structural engineers with the best of intent but with little to no involvement from plumbing designers or contractors that could point out the disconnect in what they are recommending and what construction methods are in the prior art. For example, the problem with a sanitary sewer plumbing design that incorporated flexible expansion joints all along the length of an under-slab utility is that most sanitary sewer systems function by a gravity system that has to slope downward at a minimum slope along the entire length of the plumbing system and, in addition, plumbing codes require specific minimum slopes, so it is not technically feasible to have an underslab utility system with so many flexible expansion joints slope so dramatically that at any point under a slab the subgrade could heave and/or fall without causing a negative slope that would cause the sanitary sewer system to no longer function properly, and furthermore the cost of so many flexible expansion joints would cost more than a crawlspace foundation in many cases such that, even if it were technically feasible for a specific case, it would most likely not be a logical approach compared with a crawlspace foundation. As another example, SC-11-1 diagrammatically shows a soil retainer system that has no means of stability to retain the soil.
There have been several attempts to invent methods and apparatuses with a goal being to attempt to isolate under-slab utilities from expansive soils. However, all of these attempts have failed in one form or another to provide an actual means of isolation. When the Structural Engineers Association of Texas (SEAoT) became aware of the concept behind some of the disclosed inventions for novel ways to isolate under-slab utilities, it quickly assembled approximately a dozen engineers including structural engineers, geotechnical engineers and mechanical engineers to review available technologies and make recommendations because they recognized that none of the prior art has been able to sufficiently isolate utilities and utility supports from expansive soil, in contrast to embodiments of the invention disclosed herein. In January 2021, based on the recommendations of the aforementioned group of engineers, SEAoT submitted to the International Code Council (ICC) a code change proposal to the 2024 International Plumbing Code (IPC) that would require an sufficient means of isolating under-slab utilities from expansive soil under slabs that are isolated, consistent with this invention, and would prohibit the majority of prior art methods as they do not sufficiently isolate under-slab utilities. One exception in the prior art is that it would remain permitted to install plumbing and supports after the slab is poured by removing voidforms and post-installing anchors overhead, which is in the prior art but is often thought to be cost-prohibitive for new construction. SEAoT submitted a 14 page document to ICC with the rationale for their proposed code change. The SEAoT document is available at at https://www.iccsafe.org/products-and-services/i-codes/code-development-process/2021-2022-group-a/ and is hereby incorporated by reference as if fully set forth herein herein. At the International Plumbing Code Committee Code Action Hearings, SEAoT's proposed code change was supported by testimony from various mechanical and structural engineers, the Geoprofessional Business Association, the American Institute of Architects and the American Council of Engineering Companies of Texas. The 2024 International Plumbing Code Committee then approved the proposed code change, with some modifications that SEAoT supported that clarified the intent of the proposed code change. And, the change will be a part of the 2024 International Plumbing Code when it is published. While numerous serious attempts have been made in the last several decades, the prior art methods, as described above, do not meet the requirements for isolation as will be set forth in the 2024 IPC.
It may be important to note that, while the United States Court of Federal Claims indicated in the case cited above that the mechanical engineering firm was negligent in designing a soil-supported under-slab utility under a slab-on-voidform foundation for the specific project at issue, there were approximately a dozen engineers assembled by the Structural Engineers Association of Texas, including structural engineers, geotechnical engineers and mechanical engineers, which all indicated in their collective rationale statement to ICC that designing a soil-supported under-slab utilities under a slab-on-voidform foundation was within the standard of care for each of those professions in Texas as of January 2021 when the statement was issued to ICC. The standard of care may change over time to exclude this practice, but this practice is still being used today.
And, while some building officials might interpret current code requirements to prohibit soil-supported utilities under slab-on-voidform where expansive soils are present, the only interpretation of code provisions that applies to any specific project with regard to code compliance is the opinion of the building official with the Authority Having Jurisdiction (AHJ) for that project. There are many projects in Texas where building officials issue building permits without taking any exception to soil-supported under-slab utilities under a slab-on-voidform or a crawlspace foundation, even when they are provided a copy of a soil report indicating that expansive soils are present and documentation indicating that there will remain some potential vertical movement of the subgrade after the building is occupied.
Prior art systems for vertically supporting utilities (including but not limited to sanitary sewer piping) that are designed to be located under structurally suspended concrete slabs over void forms (including but not limited to carton and plastic void forms) bearing on other foundation elements (including but not limited to piers, piles, caissons. footings, and grade beams) without a typical crawl-space access include systems that directly bear on soil within the active zone ("Direct Bear Systems"). In these systems the utilities are laid down directly on top of the soil in the active zone or on top of material (including but not limited to coarse aggregate (rocks), fine aggregate (sand), cemented sand, flowable cementitous fill, road base, lime-stabilized earth) that is laid down directly on top of the soil in the active zone.
The prior art also includes systems that indirectly bear on soil within the active zone ("Indirect Bear Systems"), in which utilities typically hang from above by a threaded rod that is supported by a primary nut bearing on the system (e.g. prior art systems known as PlumbingVoid® and Pipe-Void) which is bearing on soil within the active zone or other material that is bearing on soil within the active zone. The threaded rods typically extend up into the thickness of the concrete slab with some form of anchorage (including but not limited to a secondary nut) so that the slab can act as another support; however, the primary nut stays in place and is not removed because the operations of pouring the concrete slab and allowing it to cure prohibit any kind of convenient access underneath to remove the primary nut. Indirect Bear Systems do not have a reliable means of avoiding the risk that expansive soil could damage under-slab utilities; and, there can even be a risk of a much larger amount of damage than with Direct Bear Systems if any hangers in contact with soil corrode and pipes fall or if any soil retaining systems fail and pipes shift dramatically.
Both Direct Bear Systems and Indirect Bear Systems can allow volumetric changes (vertically and horizontally) in the active zone to cause forces to bear on the utilities which can cause the utilities to shift (including but not limited to deflecting up or down over certain regions of utility piping, breaking utilities, or causing them to leak). The Indirect Bear Systems are not capable of resisting the forces like foundation elements such as drilled piers, driven piles and sufficiently deep footings. When utilities shift too much, the utilities cannot function properly. For example, sanitary sewer piping typically requires sewage flow downhill and any portions that bend after construction, in any direction, can cause sewage to not flow properly. Even if flexible joints are installed in these utilities, the pipes themselves (including but limited to PVC, cast iron and ductile iron piping) are typically not capable of flexing as much as they may need to flex and maintain a positive slope for drainage. Unlike maintenance of sanitary sewer under crawl-space and slab-on-grade type foundations, maintenance of utilities is relatively difficult and expensive because convenient access directly to or directly above the area of concern cannot be provided, and Indirect Bear Systems often create additional obstacles to such repairs.
It is, therefore, desirable to have a system that does not bear (directly or indirectly) on any soil within the active zone but rather bears on structural elements that are bearing on soil below the active zone and/or are designed to sufficiently resist the vertical forces associated with volumetric changes in the active zone by virtue of their penetration below the active zone.
Additionally, Indirect Bear Systems are generally proprietary systems which require relying on components of the system to retain soil so that soil does not fall, slide, push, deflect, rotate, or otherwise either directly cause forces on the utilities or indirectly by means of becoming a shim where a void was intended (including but not limited to under the utility piping, above the utility piping, on either side adjacent to the utility piping, and related to any permanent system element such as saddles and hangers) to isolate the utility from potential soil-related forces, which can cause utilities to no longer function as intended and require relatively expensive maintenance. One reason these systems typically require that the proprietary components retain soil is that the systems are too wide for the main layer of void forms (immediately under the slab) to structurally span over them and reliably support rebar, workers, and wet concrete until the concrete cures. The problem with these proprietary retaining elements is that these systems have not been designed by structural engineers and there is insufficient evidence that they can reliably retain soil after construction for many common conditions which are necessary for typical construction. For example, a horizontal layer of plywood supports several feet of soil in the SuperVoid system. And, as another example, ½″ thick plastic retainer boards with the manufacturer claiming that they are acceptable to a depth of 8 feet but the height of the soil to be retained in not limited, which could lead an installer to install a retaining wall that is 8 feet tall made entirely out of ½″ thick plastic retainer board and these systems can fail.
Therefore, there is a need for a system that allows soil retainage aspects to be designed by qualified design professionals for each specific application, using methods in the prior art (including but not limited to temporary vertical cuts in cohesive soil where there is an acceptable factor of safety, sloping the grade to an acceptable stable slope such as the angle of repose for cohesionless soils, and installing permanent concrete retaining walls that become buried underground but do not extend above the bottom of the main layer of void forms immediately under the concrete slab).
Also, Indirect Bear Systems are typically buried under soil as utility lines elevations vary in depth below the slabs, which exposes the hanger (typically a threaded rod) to soil which can corrode the hanger over time if it is made of a corrodable material. The main reason that these systems are buried is that, since they are too wide for boxes above to span over them, they have to support soil above them and retain soil adjacent to them and therefore it is desired to have the soil retaining elements span as short a distance as possible. If the hanger corrodes sufficiently, it can cause the support system to fail which can cause the utilities to not function and require relatively expensive repairs. The primary nut typically needs to only support empty piping before the slab is poured. After the slab is poured and cured, as piping is filled with fluids and emptied during occupancy, the hangers support a larger load than the system supporting the primary nut was designed to support and the hangers begin to support a dynamic (not static) load which can cause failure of hangers upon jarring. Under occupied conditions, these hangers can fail if corroded.
It is, therefore, desirable to have a system that does not allow soil to contact any of the hanger assemblies. Furthermore, generally corrosion resistant materials such as fiberglass, aluminum, stainless steel and galvanized steel are available with for use in this invention to resist any ambient sub-slab moisture for an even longer useful life expectancy.
Also, since Indirect Bear Systems retain soil, the inspections required by the building code are hindered by the soil retaining components of those systems.
A desirable solution, therefore, allows full inspection of piping as required by building codes.
In Indirect Bear Systems, because they retain soil, there is not sufficient height in the systems to accommodate a sufficiently long hinge pipe with void space underneath, a rotating joint at the end of the slab-hung length of utility piping and a rotating and telescoping joint at the soil-supported end of the hinge pipe to transition between the two systems at the exterior of the grade beam. This arrangement is necessary so that, if the potential vertical movement occurs upward, the utility piping will not slope less than the minimum permitted by applicable regulations. If the potential vertical movement downward occurs, then the utility piping will not exceed any maximum slope permitted by applicable regulations.
It is, therefore, desirable to have as system that allows independent soil retaining systems so that a hinge pipe can be installed to successfully transition between slab-hung and soil-supported sections of utility piping and can utilize rotating and telescoping joints available in the prior art.
Also, Indirect Bear Systems are difficult to access after construction if it is necessary to maintain them.
It is, therefore, desirable to have a system that avoids the need for maintenance associated with damage caused by expansive soil, which can happen in the prior art as noted above. It is also desirable to have a system that allows independently designed soil retaining systems so that design professionals can create sufficiently large void spaces along the sides of the utility piping that can be more-easily accessed horizontally through openings in exterior grade beams by removing exterior backfill (rather than cutting temporary access openings vertically into the slabs and hand-digging from the opening to pipe location which can often be far from the nearest potential location for a temporary slab opening).
An example of an Indirect Bear System in the prior art device aimed at addressing the issue of damage caused by expansive soils is the PlumbingVoid@ product by VoidForm, which includes a unit having a plurality of members that, when used in combination, is intended to create a self-contained void space for the safe routing of plumbing lines, electrical lines and other conduits underground. The unit includes a plurality of selectively arrayed panel sections coupled together to form a routing path. The panel sections are supported with a plurality of braces/connectors for stability. Additional panels may be added over the top of the panel sections so as to enclose the space. Pipe is laid within the space and elevated as necessary to ensure proper drainage. Elevation is secured through the use of a clevis bracket and threaded rod configured to extend out through the space and panel sections. A fastener and washer combination is used to provide temporary support for the pipe being supported by the braces/connectors. By modifying the panel sections, routes may be customized to accommodate plumbing needs. However, this system does not isolate the utilities from expansive soil because it is an Indirect Bear System and, as noted by SEAoT in their 14 page rationale statement supporting their proposed code change to prohibit Indirect Bear Systems, the PlumbingVoid product does not sufficiently isolate utilities from expansive soil. A common PlumbingVoid detail that has been used has interior spacers "above or below pipe" which can contact the pipe and impart loads onto the piping if the soil swells or shrinks and causes the box to shift up or down more than the gap between the pipe and the interior spacers. No specific elevation for the spacers is provided on the detail and specifiers typically do not specify any clearance dimension above or below the pipe. The purpose of the spacers is to provide an intermediate bracepoint for the retaining boards, which are not designed by an Engineer for the site conditions in the standard product, to prevent excessive deflection which could pinch the pipe and cause damage. For this reason, the interior spacers are typically near the piping and so this is a legitimate concern. In addition, the U-bars at the bottom are often bare steel without any protective coating and in contact with soil such that they could corrode and fail even though they are structurally necessary to keep the two vertical retainer boards separated enough so that they do not fail and pinch the pipes, which could cause the pipes to break. It has been suggested that a "knife-edge" will occur so that no load will push the box up from the bottom; however, SEAoT indicates they believe this is an incorrect theory because, while soil does expand when it gets wet, expansive soil does not become a fluid as is evidenced by the fact that it has sufficient internal compressive strength to impart significant upward pressures and a layer of dry soil can naturally occur over a layer that becomes wet such as with deep seated swell that has been observed in many forensic investigations. The PlumbingVoid@ Washer is a large washer that is intended to fold in between two U-Bars when the box is pushed upward when soil swells. Until this folds, there is a load imparted onto the hanger so that it could buckle the hanger, especially if the hanger is about 7 feet long as the manufacturer's detail indicates it is applicable with trenches that are 8 feet deep. If the rod does not fail, the rod will impart load onto the slab that the slab must be designed for. A Structural Engineer designing the slab would need to know the locations of these hangers and design the slab to resist these loads. If the soil shrinks, the soil above the box would weigh down the top of the box, which would not allow failure of the washer and this would create an additional tension on the hanger which it was not designed for. Failure of the rod in tension could cause the plumbing to shift downward and break or require maintenance. If the soil shrinks, the bottom and sides of the box would shift down with the soil whereas the top could be suspended at the original installation elevation. If the vertical legs of the top U-Bars are not long enough, the bottom of the box could slide down enough that the top U-Bars no longer provide sufficient lateral bracing of the vertical retainer boards. If the tops of the vertical retainer board fall inward, the shifting elements could break the plumbing and/or cause shifting that requires maintenance. A ½″ thick retainer board is shown typically on each side where the detail indicates there could be 8 feet of hydrostatic soil load from a cohesionless strata; if this retainer board is not thick enough to resist the lateral soil pressures at the depths installed, the retainer board could fail inward and damage a utility pipe. The detail calls for soil to be backfilled against the retaining boards, but equipment loading can be significant. Also, there does not appear to be any typical specification expected for lateral movement associated with swelling in a typical detail that has been used in industry. Swelling of expansive soil is a three-dimensional phenomenon and some lateral movement should be expected which may cause the pipes to pinch and break or service disrupted if there is not sufficient space on each side of the clevis hangers. In applications where the PlumbingVoid@ product has been used, the product may not have had sufficient vertical leg length of the U-Bar, minimum clearance above and below the piping, minimum load capacity of the sacrificial washer to support plumbing during initial installation, and maximum ultimate load capacity of the sacrificial washer. A threaded rod and clevis support is shown in the typical detail to be in contact with soil that could cause corrosion if the Mechanical Engineer specifies steel unless it is protected in an approved manner or made of fiberglass. If the hanger and/or clevis support corrodes, the plumbing may shift downward and need maintenance in an area where maintenance is difficult to access. Mis-installations have been encountered in industry indicating that it is difficult for a plumber to understand the structural and geotechnical significance of the small details associated with the customization of the generic assembly for a specific application, thereby foiling the attempt to properly partially isolate the plumbing even further.
Another example of an Indirect Bear System in the prior art device aimed at addressing the issue of damage caused by expansive soils is the PipeVoid System manufactured by SuperVoid in which an expanded metal lath shape supports oriented strand board or plywood under an under-slab utility pipe that is buried in soil over the apparatus. This soil is placed on top of the SuperVoid product and plumbing is placed on that soil, with hangers extending vertically to be received by the slab when the slab is installed. If expansive soil swells under the assembly, the soil can cause the SuperVoid product to lift up, which would cause the soil to lift up, which would cause the plumbing to lift up in places. This uplift can be contrary to the hanger and clevis support which can anchor the pipe at a fixed location at supports, causing distortion in sanitary sewer lines that may cause clogs or break the lines. The SuperVoid product is comprised of expanded metal lath and plywood. It is not likely that the expanded metal lath would corrode sufficiently soon after occupancy. Some have claimed that these products cannot transfer load because they form a "knife edge" where the soil splits as it heaves. This is an invalid theory which assumes soil is a fluid when expansive soil is associated with moisture migration through partially saturated soils that can leave soils near the surface relatively dry as soil deeper down in an expansive strata swell as a "deep seated swell". In reality, just as expansive soil has proven to push piping up when buried, expansive soil can push up on any material. The pressure required to resist all swell in these circumstances if often thousands of pounds per square foot; the metal lath product is not sufficient to resist these loads. If the expanded metal lath compresses like a spring, there still is load that is transferred upward that the plumbing is not designed to accommodate. And, many Mechanical Engineers do not have the training or experience to predict what the stresses and strains in the plumbing would be under these circumstances, much less verify that they will not damage the piping or interrupt service. In addition, if expansive soil swells on each side of the assembly, the soil can cause the plumbing to lift up in places. A typical detail used for the product calls for cohesionless, granular material; however, expansive soil swells laterally and upward, which can cause compression arches to form and transmit load onto the piping, even in cohesionless, granular material. Furthermore, this approach uses plywood to retain the soil above a voidspace but the plywood may decay over time and cause the soil to cave in under the piping, which could allow expansive soil swelling to push pipes upward, even though the hangers and clevis system would resist this upward movement, and also create the plumbing problems described above. If the rod does not fail in buckling, the rod will impart load onto the slab that the slab must be designed for. A Structural Engineer would need to know the locations of these hangers and verify that the slab can resist these loads. If the soil shrinks, the soil above the plumbing could drag down the plumbing which is at fixed elevations at each hanger, which could require maintenance. The plywood is covered on top with a covering, but the bottom is exposed to moisture from the subgrade, which is typically sufficient to degrade carton voidforms soon after construction. In addition, the soil retainers are shown to sit on the ground when installed and not have any extension buried below the trench subgrade. If the expanded metal lath does corrode, the plastic soil retainers on each side do not have sufficient resistance at the bottom to prevent lateral movement caused by soil loading, which could cause material to fill into the proposed voidspace. A galvanized threaded rod and clevis support is shown in contact with soil that could cause corrosion. If the hanger and/or clevis support corrodes, the plumbing may shift downward and need maintenance in an area where maintenance is difficult to access.
Another example of an Indirect Bear System in the prior art device aimed at addressing the issue of damage caused by expansive soils is the PipeVoid System manufactured by SuperVoid in which an expanded metal lath shape supports oriented strand board or plywood over an under-slab utility pipe, wherein various soil materials are installed over the oriented strand board or plywood. In this application, many concerns are similar to those expressed for the above example with the PipeVoid product under the under-slab utility pipe. In this application though, there is a SuperVoid product which provides no voidspace above the plumbing in case the soil shrinks. In this version of the typical detail, it is possible for the plywood to decay at the initial suspension nut which would theoretically allow the system to slip upward. However, a threaded rod as part of a hanger assembly could cause compression on the hanger that could cause it to buckle, especially given the note on the typical detail to not compact soil above the plywood. In this typical detail, the plywood deteriorating could allow soil to fall down under the piping and fill in the voidspace, which would allow expansive soil to heave and cause the plumbing to shift upward. If the soil shrinks, the soil above the box would weigh down the top of the box, which would create an additional tension on the hanger which it was not designed for. Failure of the rod in tension could cause the plumbing to shift downward and break or require maintenance. There does not appear to be any specification in the detail accounting for lateral movement associated with swelling. Swelling of expansive soil is a three-dimensional phenomenon and some lateral movement should be expected which may cause the pipes to pinch and break or service disrupted if there is not sufficient space on each side of the clevis hangers.
Yet other examples of Indirect Bear Systems in the prior art are specified on construction documents issued by Mechanical Engineers, such as installing a strut channel over a narrow trench with a hanger assembly suspended by the strut channel. The soil can collapse into the trench because there is no retaining structure. And, additionally, the channel is bearing on the subgrade which can rise or fall with volumetric soil change, which would cause the loads to transfer to the nut supporting the hanger assembly that would then cause the load to transfer into the slab. The slab would need to be designed for this load and, more importantly, the load can cause the threaded rod of the hanger assembly to buckle, causing the utilities to shift and no longer function as intended.
There is, therefore, a need for a system that provides adequate isolation of under-slab utilities from volumetric soil changes under slabs of slab-on-voidform foundations for many project types in geographic locations where soils undergo volumetric changes after initial construction of a project is complete.
Also, when foundation systems are isolated from expansive soil movement by voidforms or crawl spaces, if one attempts to isolate any slab-hung (at essentially a constant elevation) under-slab utilities (including but not limited to sanitary sewer systems, domestic water lines, fire protection lines, roof drains, natural gas lines, electrical conductors, telecommunications systems, etc. . . . ) from expansive soil, it is necessary to successfully transition utilities to a soil-supported utility condition at the building perimeter.
One challenge to transition when applied to a crawlspace foundation is that, because the site beyond the perimeter of a crawlspace foundation typically has expansive soil which can cause problems as systems must transition from a building condition to a site condition. Consequently, it is common for sanitary sewer plumbing systems to be installed wherein the under-slab plumbing near the perimeter is not hung over an under-utility space but rather buried in the subgrade because main sanitary sewer lines which serve the under-slab utility line are typically very deep considering that traditionally sanitary sewer systems operate by gravity flow where possible. Where under-slab utilities under crawlspace building foundations are not isolated, which can often extend very far into the interior of a building where a progressively deep sanitary sewer main is installed under a building to collect wastewater from many fixtures, expansive soil often causes damage to the under-slab utilities needing repair. Crawlspace foundations are required by the many building codes to have access and ventilation. Where such access and ventilation are provided, it is possible to dig up a buried utility line and repair the line, but clear height conditions are often extremely limited to make the construction as economical, making these utility repairs sometimes more expensive than with a slab-on-grade system, and the repairs are not necessarily permanent because the underlying cause of the problem can continue over and over again with time.
Flexible expansion joints have been used in the prior art, such as those describe in IAPMO PS 51, Industry Standard for Expansion Joints and Flexible Expansion Joints for DWV Piping Systems as published by the International Association of Plumbing and Mechanical Officials (IAPMO), in which DWV Piping refers to drain, waste and vent piping used in sanitary sewer systems. A flexible expansion joint can have a telescoping fitting that allows axial contraction and elongation with a rotating fitting at each end wherein each end rotates, with internal gaskets that can be suitable for sanitary sewer systems and a different arrangement of internal gaskets that can be suitable for pressurized water applications such as domestic water or automatic fire sprinkler water supply pipes. Thus, flexible expansion joints can allow one end of the fixture to be at a constant elevation while the other end can lift or drop vertically, and in theory they can lift or drop the magnitude of the potential vertical movement caused by volumetric soil changes. However, there are challenges with installing such a fixture.
For example, if the flexible expansion joint is buried in soil, expansive soil may cause damage to the length of the pipe between rotating ends, which the pipe is not designed to withstand. Additionally, if the flexible expansion joint is buried in soil, it will reduce the useful life of the fixture compared to unburied conditions because it is has moving parts in soil. Over time, through cyclical flexing, soil particles can intrude and interfere with the intended operation of the moving components. If the flexible expansion joint is buried, it cannot easily be inspected during the life of the facility and replaced as needed. In fact, applicable regulations require certain fixtures like this be accessible for this reason. Also, if the flexible expansion joint is not buried, one end will need to be soil supported. At the soil-supported end, to successfully isolate the fixture from expansive soil, the soil needs to be retained so that the soil does not encroach on the clear vertical distance required under the length of the fixture to allow for the soil to rise the estimated potential vertical movement. The retaining structure, however, cannot be part of the foundation but must rather be soil-supported and allow for the estimated potential vertical movement up or down. At the building perimeter, however, there needs to be a foundation element such as a grade beam, which is to remain at essentially a constant elevation. If one were to simply have soil-supported piping outside of the building extending from an unfilled trench through a vertically slotted hole, the weight of the fixture when being installed or replaced could cause a structural instability which would lift the soil-supported pipe, causing it to rotate which could damage the plumbing and possibly cause injury. Furthermore, in the conditions for the case described above, any pressure on the piping up or down would cause the pipe to push up or down on the soil-retaining system, which can damage the pipe. Also in these conditions, any footing/counter-weight to address or pipe protection system to address issues could change the potential vertical movement of the soil at those elements, which could cause a negative drainage scenario (where water drains to the building instead of away, potentially causing more vertical movement than originally estimated) if the soil at the plan locations of such system has a lower potential vertical movement than the soil around such system. Also, any systems such as those described cannot be bonded to the utility line, which may need to be replaced over the life of the facility. Also, mechanical engineers typically design and specify utilities up to 5 feet from the building perimeter with civil engineers specifying the work beyond, and there is a desire to keep any kind of transition system within this boundary so as to stay within the scope of a single design discipline and avoid the expensive miscoordination that can occur if a site utility plan is designed assuming utilities can be run without consideration of a transition system up to 5 feet away from a building perimeter and there is a conflict discovered after installation of site utilities which requires that an entire site utility system be removed and replaced simply because the industry commonly understands the basic scope of a mechanical engineer designing utilities to end 5 feet away from a building.
Furthermore, methods in the prior art for clamping, such as a standard pipe clamp and standard pipe strap are not sufficient for clamping onto a non-structural pipe and mounting it onto a perpendicular concrete element such as a gradebeam with an over-sized hole so that the clamp can resist axial forces in either direction, transverse forces, and moments to allow a non-structural pipe such as a pvc sanitary sewer pipe can cantilever out to support an end of a flexible expansion joint, especially not a clamp in the prior art that can also be adjusted and remounted.
In the prior art, a standard clamp consists of two halves that are bolted together and, when bolted together, they form a circular opening that can be clamped around a pipe. Each half of the standard clamp has flanges that extend so that, for example, a vertical pipe can be clamped and supported vertically on a horizontal surface but this does not resist upward movement on the pipe and it does not resist transverse movement. In general, it is not typically necessary to anchor anything to a standard clap because the pipe itself can be supported and braced as necessary. In and of itself, a standard clamp is not capable of being bolted to a surface that is perpendicular to the pipe unless potentially bolts are inserted in between gaps between the two halves of the clamp, and in this case the distances of the bolts from the pipe in standard configurations are generally not sufficient to avoid reinforcement in a concrete element and have sufficient edge distance to comply with minimum building code requirements or to provide a sufficiently large enough diameter bolt to be capable of resisting the required forces. For example, most building codes require that plumbing be isolated from any elements with felt or a gap so that the plumbing can be removed and replaced over time if necessary, and the oversizing of the hole for this alone can make it difficult for bolts through the gap between halves of a pipe clamp to be successful, and if the pipe elevation needs to be adjusted after mounting it is likely that the new location will partially overlap with the old bolt and make it necessary to core out the old bolt and make the remediation even more expensive.
A standard pipe strap is a method of mounting a pipe to a surface, however it is only suitable for mounting a pipe that is parallel to a concrete face whereas a pipe needs to cantilever out perpendicular from a foundation element to support a flexible expansion joint in this invention. In the prior art, attempts have been made to try to geometrically arrange a concrete face in parallel with a pipe and use a pair of standard pipe straps so as to accommodate the need for resistance to axial forces, transverse forces and moments and provide construction tolerance in vertical elevation, however such attempts require an elaborate geometry be constructed with a concrete protrusion cantilevered from a foundation for this purpose and the field tolerances on the plan location of such a parallel face must be relatively precise, and this approach has proven difficult in the field because it is not adjustable.
Another problem is that attempting to fabricate some kind of brace in the field raises other concerns. For use with a system that protects plumbing under a slab of a slab-on-voidform foundation, it is necessary by some building code provisions for components subject to corrosion to be protected in an approved manner and not simply be unprotected steel. If a standard pipe clamp is modified in the field by welding it to a support element such as a steel component that is galvanized, the welding process will destroy the galvanized coating that protects the steel from initial corrosion. If a standard pipe clamp is modified in the field by welding it to a support element such as a component that is stainless steel, the welding process will be expensive because a stainless-steel welding operation will need to be set up on a project. Furthermore, it may be difficult to get proper access to do welding, for a welding rod to reach where it needs to reach, and for proper inspection of a weld between a standard clamp in the field and any other component used in an attempt to stabilize a standard pipe clamp. Plastic components can break in the field if overstressed during installation and/or field modification.
There is, therefore, a need for an improved method of transitioning under-slab utilities of isolated foundation systems to soil-supported utility conditions suitable for both crawlspace foundations as well as slab-on-voidform foundations.
Also, voidforms are not sufficiently rigid for a sufficient time to provide support to under-slab utilities under slab-on-voidform foundations before the slab is poured. Therefore, utility suspension systems must bear on the ground. Foundation elements can do this, but they are typically far apart so that a reinforced concrete slab can span between them, which makes it an added cost to install a utility framing system that bears only on foundation elements. Any support that bears on the ground itself is not acceptable if it can allow forces from volumetric soil changes to push/pull on utilities and/or foundations and cause damage.
Therefore, there is a need for a method and system whereby a framing system that is flexibly positioned and does not bear on the ground.
Also, it is necessary to retain soil when supporting under-slab utilities over a voidspace that extends below the main layer of voidforms under a slab-on-voidform foundation slab. And, it is common that under-slab utilities, and voidspaces under those utilities, need to extend below the main layer of voidforms if it is desired to effectively isolate them from expansive soil. Benching soil to retain this soil is problematic because it is time-consuming to map out in 3 dimensional space how to retain soil to protect the distributing piping systems for under-slab utilities which can be complex, and it is time consuming to grade the benched trenches to the proper elevation so that when voidforms are placed the bottom of the slab is at the correct elevation, and soil can slough off into the trench, requiring time-consuming, regular maintenance of the trenches as well as risking loss of support for the boxes above which could require either excavating a wider trench or trying to reconstruct the sloped soil of the original excavation. The time required is a challenge in that it costs a lot for labor but also challenging in that carton voidforms often used in slab-on-voidform foundations need to be placed on a dry subgrade and concrete poured before a rain event occurs (to avoid deterioration of the carton voidforms which could cause the voidforms to collapse when placing fresh concrete, and it can be difficult to find sufficient dry periods in the weather to accomplish all that is needed when the sides of the trenches need to be benched. The only alternative to benching when the utilities are below the bottom of the main layer of voidforms is to install a relatively short retaining structure (often less than 4 feet in height) which can be more expensive than benching if methods of installing a retaining structure in the prior art are used. Retaining structures are expensive to form with formwork and expensive in that they need to extend deep enough below the bottom of the utility trench so as to sufficiently resist overturning and sliding from soil pressures behind the retaining structure as the building codes require retaining structures have a minimum factor of safety of 1.5 against overturning and sliding. These type of retaining structures are typically concrete, reinforced with conventional rebar, that requires additional labor costs, materials costs and time which increases the construction schedule on a project. A challenge with utility trench walls under slab-on-voidform foundations is that the soil is typically a highly expansive clay, which the International Building Code deems "unsuitable" for use behind a retaining structure. Complicating and making retaining structures in the prior art more expensive is the fact that expansive soil can create very large lateral pressures on retaining structures when the expansive soil swells due to moisture content changes, and there is wide disagreement within the Geotechnical Engineering community on how great these pressures are, with some indicating that may be thousands of pounds per square foot. Many Geotechnical Engineers recommend that all expansive soil be removed behind a retaining structure and be replaced with less expansive "select" fill. There has been litigation claiming engineers were negligent for allowing expansive soil backfill behind a retaining structure but not accounting for the amount of rotation that can occur when these walls are embeded in the ground, as is common in the industry. It is also expensive and risky to cut voidforms around intricate spaces of complex plumbing distribution systems in the plumbing trenches. Manufacturers of such voidforms do not recommend overly-cutting the forms because they are designed to collapse in their manufactured "whole" condition. The risk is that the voidforms could collapse when placing concrete.
Therefore, there is a need for an underslab utility suspension system that incorporates improved soil retention suitable for both crawlspace foundations as well as slab-on-voidform foundations.

System and method for protection of under-slab utilities from changes in soil volume


Energy absorbing structure disposed beneath the cargo area of an aircraft provides maximum energy absorption and structural strength using carbon fiber reinforced epoxy composites. The energy absorbing structure uses laminated stanchions having ply drop-offs to produce stable, progressive crushing of the stanchions during a wheels-up crash landing. Integrally formed flanges on the stanchions allow direct mounting of the stanchions on the structural members of the aircraft, without the need for specialized fittings.

1. Field of the Invention
This invention broadly relates to energy absorbing structures, and deals more particularly with energy absorbing elements such as stanchions and assembly fittings used in aircraft.
2. Description of the Related Art
An important objective in the design of modern military and civilian aircraft is the protection of occupants in the event of a survivable crash. Crash injuries may be caused by high acceleration loads experienced by the occupants, or the loss of structural integrity of the aircraft. Crashworthy designs for aircraft require the fuselage to provide energy absorption in order to slow down the aircraft during a crash impact. Controlled deceleration of the aircraft during impact reduces inertial loads on the occupants, and assists in maintaining structural integrity of the aircraft. The area beneath the fuselage floor can form an important part of the energy absorption system in the event of a crash, since this area is normally the part of the aircraft that is initially crushed during ground impact.
Earlier generations of crash energy absorption systems relied heavily on metal components to absorb aircraft kinetic energy during a crash. However, the increasing use of composite materials in aircraft designs has resulted in newer crash energy absorption systems that rely on components formed of composite materials. Energy absorbing systems that use composite materials present a design challenge because these materials are often brittle and do not exhibit either plasticity or high elongation prior to failure. In order to solve these design problems, a number of solutions have been proposed, including varying the density of stitching used in stitched composite structures, and using so called ply drop-offs to sustain a crushing process after it is initiated. These design solutions may sometimes be difficult to incorporate into manufacturing processes without significant cost increases. In addition, previous design solutions were limited to protecting occupants from impact forces acting vertically on the aircraft, rather than from off-vertical forces which can be imposed on the fuselage if the aircraft rolls slightly before ground impact.
Accordingly, there is a need for energy absorbing structure for aircraft that both improves crashworthiness and is cost effective to implement. The invention is directed towards satisfying this need.


A transfer needle comprises: a liquid-specific member; and a medicament-specific member to be separably connected or joined to the liquid-specific member in a liquid-tight state. The liquid-specific member comprises: a liquid-specific hollow needle projecting toward the opposite side from the medicament-specific member. The medicament-specific member comprises: a medicament-specific hollow needle projecting toward the opposite side from the liquid-specific member and communicating with the liquid-specific hollow needle. A female luer is provided on at least one of the liquid-specific member and the medicament-specific member at a position opposing to the other. The female luer communicates with the one hollow needle and is separably connected with an injection needle connecting portion of a syringe in a liquid-tight state.

1. Field of the Invention
The present invention relates to a transfer needle and, more specifically, to a transfer needle that enables safe, easy and reliable injection of liquid such as solvent or drug solution from its own container into a container with medicament contained therein, when dissolving the medicament in liquid such as solvent or drug solution and preparing drug solution for preparing fluid infusion and the like.
2. Description of the Related Art
Medicaments which are chemically unstable and may change their natures in a state of fluid infusion, such as antibiotics, anticancer agent, or blood preparation, are normally stored in a vial sealed with a rubber plug in a freeze-dried state, and then those medicaments are dissolved in a solvent such as distilled water, physiological salt solution, or glucose liquid and drug solution are prepared immediately before use.
In the most general method used for such dissolving and preparing procedure in the related art, a solvent is sucked out from a container containing the solvent by using a metallic hollow needle and a syringe and injected into a container with a medicament therein, and then the medicament is dissolved in the solvent to prepare a drug solution, and the prepared drug solution is returned to the syringe. However, this method is not only complicated, but also associated with a risk of accidental puncture by the metallic hollow needle. Therefore, various types of transfer needles which can perform dissolving and preparing procedure safely, easily and reliably are proposed (For example, JP56-9464B, JP54-16152B, JP49-47507B).
However, in the transfer needle in the related art, there are problems as described below. That is, the transfer needle is generally formed by injection molding, and thus there arise the following problems. For example, as shown in FIG. 38, a transfer needle 77 comprises a base plate 78, an upper hollow needle 79 projecting upward from the base plate 78, a lower hollow needle 80 projecting downward from the base plate 78 and communicating with the upper hollow needle 79, a skirt 81 provided so as to project upward from the outer peripheral edge of the base plate 78, a skirt 82 provided so as to provide downward from the outer peripheral edge of the base plate 78, and so on. When manufacturing the transfer needle 77 as described above by injection molding, for example, a method of using upper and lower metal molds 83, 84 as shown in FIG. 39, forming an insertion portion 84A to be inserted into an insertion hole 83A of the metal mold 83 on the metal mold 84, and molding the upper hollow needle 79 between the insertion hole 83A and the insertion portion 84A is conceivable.
However, in this method, the length L of the portion to be positioned inside the lower hollow needle 79 plus the insertion portion 84A of the metal mold 84 (this portion is supported to the metal mold 84 only at the lower end) is significantly long, and hence there arises a problem of strength. Therefore, the metal molds 83, 84 as shown in FIG. 40 are used for all practical purposes.
As described above, in the integral transfer needle in the related art, it is necessary to abut the small diameter liquid-specific hollow needle 79 and the medicament-specific hollow needle 80 against each other and mold them together. Therefore, when the metal molds 83, 84 are clamped too tight when molding, the metal molds 83, 84 may be broken. In contrast, when the metal molds 83, 84 are clamped with insufficient force, there arises such problem that flash may be generated at a portion 85 between the metal molds 83 and 84, and hence communication between the liquid-specific hollow needle 79 and the medicament-specific hollow needle 80 becomes defective. In this manner, in the related art, there was a problem in that adjustment a mold clamping force of the metal molds 83, 84 is difficult and hence molding of the transfer needle 77 cannot be performed easily.
In addition, the respective metal molds 83, 84 are formed with elongated ring-shaped holes 83B, 84B for forming hollow needles 79, 80 respectively in the vertical direction. In this case, when the diameters of the ring-shaped holes 83B, 84B are small, it is difficult to form these holes 83B, 84B, and it is further difficult to reduce the diameter of the insertion hole 83A and the insertion portion 84A, which requires a high level of technology. Therefore, when considering the molding stability of the transfer needle 77, the diameters of the ring-shaped holes 83B, 84B are obliged to be larger, and hence the diameters of the respective hollow needles 79, 80 increase correspondingly.
As shown in FIGS. 41(A) to (C), when the hollow needle 71 of the transfer needle is punctured into a rubber plug 72 of a vial 70, such phenomenon that the hollow needle 71 is pressed back by a resiliency of the rubber plug 72, that is, a kick-back phenomenon occurs. However, when the diameter of the hollow needle 71 is large, a force to be pressed back when the hollow needle 71 is punctured into the rubber plug 72 increases correspondingly, whereby the possibility that communication between the hollow needle 71 and the interior of the vial 70 is blocked or the hollow needle 71 comes off the rubber-plug 72 increases.
Also, as shown in FIGS. 37(A) to (C), when the metallic hollow needle 71 of the transfer needle is inserted into the rubber plug 72 of the vial, the cutting edge 73, which is formed like a pointed cutting edge, is punctured into the rubber plug 72 first and inserted into the rubber plug 72 as if it tears the rubber plug 72, and then the rear portion thereof is inserted in sequence into the rubber plug 72. In this case, since the rear (end) portion of the opening edge of the cutting edge 73 of the hollow needle 71, that is, a heel portion 74 is keen, a (coring) phenomenon that rubber material of the rubber plug 72 is cut off by the heel portion 74 tends to occur, whereby there was a possibility that small chips 75 of rubber are mixed into the prepared drug solution. Coring may also occur as in the case that the diameter of the metallic hollow needle 71 is large.
Furthermore, in the related art, when the drug solution is prepared in the vial by using the transfer needle, and then the prepared drug solution in the vial is transferred in turn to the syringe, it was necessary to pull the hollow needle of the transfer needle off the rubber plug of the vial, and then puncture the metallic hollow needle, which is connected to the syringe, again into the rubber plug to suck the prepared drug solution into the syringe. Therefore, there was a problem of generation of coring due to twice-puncture of the needle with respect to the rubber plug.
In order to solve this problem, such technology including the steps of inserting the respective hollow needles of the transfer needles into the rubber plug of the upper and lower vials respectively, mixing solvent and medicament in the both vials and preparing a drug solution, then when the empty upper vial is brought apart from the lower vial upward, bringing the distal (end) portion of the upper hollow needle or the like apart from the main body of the transfer needle, and dropping the distal (end) portion of the lower hollow needle as well in the lower vial, thereby taking the prepared drug solution out from the lower vial by the syringe through the main body of the transfer needle is proposed (for example, JP63-114649U). However, in this technology, since the distal ends or the like of the respective hollow needles remain in the respective vials, it is troublesome to dispose the distal (end) portions of the respective hollow needles and the respective vials separately, and in addition, the possibility to cause a needle-puncturing accident by the distal end portions of the respective hollow needles is high, and hence practical application was difficult.