Upper bound analysis of the pullout capacity of shallow horizontal strip anchor plate embedded in heterogeneous soils

Considering the heterogeneity of soils, a kinematic admissible velocity field was constructed to characterize a proposed curve failure mechanism of soils above the shallow strip anchor plate on the basis of the nonlinear Mohr-Coulomb criterion and the associated flow rule. The ultimate pullout force and failure mechanism of the shallow strip anchor plate were derived using the upper bound analysis method and the variation minimum principle. The influences of the embedded depth, heterogeneity and nonlinear strength features on its ultimate pullout force and failure mechanism were discussed, and comparisons between this upper bound solution and the existing solutions were also conducted. The results show that the embedded depth, heterogeneity and nonlinear strength features have obvious effects on the ultimate pullout force and failure mechanism of the shallow strip anchor plate. With the increases in the embedded depth and heterogeneity coefficient as well as the decrease in the nonlinear strength coefficient, the ultimate pullout force of the shallow strip anchor plate increases together with the failure zone (depth and width) of soils. The calculation results of this upper bound solution show good agreements with those of the limit equilibrium method and limit analysis by the finite element method, which shows the effectiveness of this proposed curve failure mechanism and heterogeneity law of soils, and provides some references for the design of shallow strip anchor plates.