Estimating the critical height of unsupported trenches in unsaturated soil
University of New Brunswick
Trenching (or excavating) is integral to construction activities in the practice of geotechnical, mining, tunnelling, and geo-environmental engineering. Many projects are initiated by excavating trenches for infrastructure to be installed. Workers are often required to enter trenches during the construction process, which may present serious risks. Trench failures can result in death and/or damage to adjacent properties, therefore trenches should be excavated with extreme precaution. The critical height (i.e. maximum depth that can be excavated without failure) is the most important design consideration for ensuring the stability of unsupported trenches. Excavation work is often done in unsaturated soils, in which case the critical height of unsupported trenches can be more reliably estimated by considering the influence of matric suction. The purpose of this study is to investigate the influence of soil type, the matric suction distribution, and surcharge pressure in assessing the critical height of unsupported trenches. Extended Rankine earth pressure theory, the limit equilibrium method, and finite element analyses were used to estimate the critical height of unsupported trenches in two unsaturated soils.
Ujenzi wa mashimo ya chini ya ardhi katika ardhi isiyo na maji ya maji ya chini ya ardhi ya chini ya ardhi ya chini ya ardhi ya chini ya ardhi ya chini ya ardhi ya chini ya ardhi ya chini ya ardhi ya chini ya ardhi ya chini ya ardhi ya chini ya ardhi ya chini ya ardhi ya chini ya ardhi ya chini ya ardhi ya chini ya ardhi. Miradi mingi huanzishwa kwa kuchimba mitaro kwa ajili ya ujenzi wa miundombinu. Mara nyingi wafanyakazi huhitajiwa kuingia katika mitaro wakati wa ujenzi, jambo ambalo laweza kusababisha hatari kubwa. Kushindwa kwa mitaro kunaweza kusababisha kifo na au uharibifu wa mali zilizo karibu, kwa hiyo mitaro inapaswa kuchimbwa kwa tahadhari kubwa. Urefu muhimu (yaani Uwezo wa kuchimba chini ya ardhi bila kushindwa ni muhimu zaidi kwa ajili ya kuhakikisha uthabiti wa mashimo yasiyo na msaada. Kazi ya kuchimba mara nyingi hufanywa katika udongo usio na unyevu, katika kesi ambayo urefu muhimu wa mitaro isiyo na msaada unaweza kukadiriwa kwa uaminifu zaidi kwa kuzingatia ushawishi wa suction ya matrix. Lengo la utafiti huu ni kuchunguza ushawishi wa aina ya udongo, matrix suction usambazaji, na shinikizo surcharge katika kutathmini urefu muhimu ya trenches unsupported. Kwa mfano, Rankine's Extended Earth Pressure Theory (EARTT) na Limit Equilibrium Method (LEM) ni mbinu za kuchunguza urefu wa matundu ya ardhi katika udongo wa un-saturated.