Experimental Investigation of Soil Arching Mobilization and Degradation under Localized Surface Loading

Soil arching exists in many geotechnical applications, including tunnels, buried pipes, and geosynthetic-reinforced pile-supported (GRPS) embankments. Soil arching has been mostly investigated using trapdoor tests under soil self-weight and/or uniform surcharge. In real applications, localized surface loading, such as traffic loading, may be applied onto soil and affect or degrade soil arching. Geosynthetic reinforcement is used in GRPS embankments or over buried pipes and may have effects on soil arching mobilization and degradation under localized surface loading. The effects of surface traffic loading and geosynthetic reinforcement on soil arching have not yet been well investigated. This study investigated the effects of static surface footing loading on soil arching mobilization and degradation in geosynthetic-reinforced and unreinforced embankments using trapdoor model tests under a plane-strain condition. These model tests consisted of both trapdoor and loading stages, which were used to evaluate the mobilization and the degradation of soil arching, respectively. The trapdoor test results show that the displacement of the trapdoor induced progressive mobilization of soil arching and geosynthetic reinforcement minimized soil arching mobilization due to the change of the soil deformation. Localized surface loading degraded soil arching. Single and double layers of geosynthetic reinforcement helped maintain soil arching under localized surface loading. The test results also show that the biaxial geogrid was more effective than the uniaxial geogrid with similar tensile strength and stiffness in carrying the load due to its better lateral restraint. Geosynthetic reinforcement increased the applied surface load required to fully degrade soil arching and eliminate the benefit of the geosynthetic.