The movement of superheavy loads (SHLs) on the Nation's highways is an increasingly common, vital economic necessity for many important industries, such as chemical, oil, electrical, and defense. Many superheavy components are extremely large and heavy (gross vehicle weights in excess of a few million pounds), and they often require specialized trailers and hauling units. At times, SHL vehicles have been assembled to suit the load being transported, and therefore, the axle configurations have not been standard or consistent. Accommodating SHL movements without undue damage to highway infrastructure requires the determination of whether the pavement is structurally adequate to sustain the SHL movement and protect any underground utilities. Such determination involves analysing the likelihood of instantaneous or rapid load-induced shear failure of the pavement structure.
The goal of this project was to develop a comprehensive analysis process for evaluating SHL movement on flexible pavements. As part of this project, a comprehensive mechanistic-based analysis approach consisting of several analysis procedures was developed for flexible pavement structures and documented in a 10-volume series of Federal Highway Administration reports—a final report and 9 appendices.(1-9) This is Analysis Procedures for Evaluating Superheavy Load Movement on Flexible Pavements, Volume VII: Appendix F, Failure Analysis of Sloped Pavement Shoulders, and it details the method developed for investigating the stability of sloped pavement shoulders under SHL-vehicle movements. It also presents verification of the proposed approach using the measurements obtained from tests on full-scale pavement structures. This report is intended for use by highway agency pavement engineers responsible for assessing the structural adequacy of pavements in the proposed route and identifying mitigation strategies, where warranted, in support of the agency's response to SHL-movement permit requests.
Nadarajah Sivaneswaran (HRDI-20; ORCID: 0000-0003-0287-664X), Office of Infrastructure Research and Development, Turner-Fairbank Highway Research Center, served as the Contracting Officer's Representative.
The movement of superheavy loads (SHLs) on the Nation's highways is an increasingly common, vital economic necessity for many important industries, such as chemical, oil, electrical, and defense. SHL hauling units are much larger in size and weight than standard trucks. SHL gross vehicle weights may be in excess of a few million pounds, so they often require specialized trailers and components with nonstandard spacing between tires and axles. Accommodating SHL-vehicle movements requires determining whether pavement is structurally adequate and analyzing the likelihood of instantaneous or rapid load-induced shear failure. As part of the Federal Highway Administration project, Analysis Procedures for Evaluating Superheavy Load Movement on Flexible Pavements, a method of investigating the stability of a sloped pavement shoulder under an SHL-vehicle movement was developed by modifying the well-accepted wedge method. This new method, with the use of 3D-Move Analysis software, is capable of considering a layered medium with distinct layer-stiffness values along with the unconventional SHL-vehicle loading configuration.(10) To account for the existence of a sloped pavement shoulder in 3D-Move Analysis, computed SHL vehicle-induced stresses are modified using a stress adjustment factor for a sloped shoulder (SAFShoulder). SAFShoulder was determined based on results from large-scale pavement experiments conducted in this study.