Performance of geosynthetic-reinforced soil walls at failure

A series of centrifuge tests was conducted to investigate the performance of geosynthetic-reinforced soil (GRS) walls under failure conditions and evaluate the applicability of limit equilibrium (LE) analysis for the internal stability design of GRS walls. The test variables were reinforcement material and wall height. The failure process, failure mode, and wall facing displacement were observed and discussed. The test results revealed that the wall deformed gradually as the applied g-level increased. At prefailure stage, excessive settlement occurred close to the wall crest, and a distinct subsidence developed at the top of the wall at the end of the reinforced zone. At the moment of failure, wall deformation suddenly increased, and the wall collapsed instantly. The location of the critical failure surface of the GRS wall was affected by the reinforcement inclusion. The upper limit of the critical failure surfaces of all tests was bounded by Rankine's theory. Back-calculation from the centrifuge test results revealed that all the wall models with different reinforcement and wall geometric parameters yielded a single equivalent earth pressure coefficient KT, and the KT value was comparable to theoretical active earth pressure coefficients. The failure g-level and location of the critical failure surface predicted by LE analyses were in good agreement with the observed ones from centrifuge tests, validating the applicability of LE analysis as a basis for the internal design of GRS walls. On the basis of the established relationship between the factor of safety and wall facing displacement, the inherent factors of safety ranged from FSs = 1.5 to 2.5 for the wall deformation under serviceability conditions, as suggested in several design guidelines. The maximum horizontal facing displacement reached 8% ~ 12% of the wall height at incipient wall failure. Compared with the wall deformation data in the literature, the global reinforcement stiffness was observed to have a significant influence on the maximum horizontal facing displacement of GRS walls at failure.