Stability analysis of L-shaped caisson quay wall under strip load

The failure surfaces developed in the sand backfill behind an L-shaped caisson quay wall were classified into three failure modes according to their number and geometries. The variational method was employed by establishing the equilibrium equation of the factor of safety and determining its minimum value. The resulting nonlinear differential equations were solved using optimization methods, with the initial values determined through random iteration. To verify the accuracy of the proposed theory, it was applied to analyze laboratory model tests on L-shaped caissons and retaining walls presented in the literature. The obtained resultant earth pressure and failure surfaces exhibit agreeable consistency with model test results on L-shaped caissons. The normalized lateral pressure predicted by the proposed model is compared with those obtained from different theoretical approaches. The results obtained from these approaches to calculate L-shaped retaining walls fall within a relatively narrow range of 0.11–0.20, while the proposed model gives values of 0.17-0.18. The predicted first and second failure surfaces agree closely with the experimentally observed slip surfaces, with R 2 values not lower than 0.9788 and 0.9998, respectively.