Pore Water Pressure and Settlement of Clays under Cyclic Shear: Effects of Soil Plasticity and Cyclic Shear Direction

Abstract

To estimate the cyclic shear-induced ground settlement of clay layers, cyclic simple shear tests were carried out on three normally consolidated clays with different plasticity. The pore water pressure accumulation during cyclic shear and the settlement at the postcyclic recompression stage were measured in tests with unidirectional and two-directional shearing, with different phase shifts between the shear strains applied in the two orthogonal directions and a wide range of shear strain amplitudes. All tests were performed with 200 cycles. In conclusion, firstly, the discrepancies of the pore water pressure accumulation and postcyclic settlement between unidirectional and two-directional cyclic shear were quantified, and the effects of cyclic shear direction on these properties were then described by the total length of strain path. Secondly, a method for estimating the cyclic shear-induced pore water pressure accumulation and postcyclic settlement of clayey soils with different plasticities was then developed considering the effect of cyclic shear direction.