饱和土体静态液化失稳理论预测

通过在屈服准则和剪胀性方程中引入材料状态参数,建立了一个与材料状态相关的本构模型,用于模拟不同初始孔隙比和围压下土体的应力-应变关系。基于二阶功理论,建立了饱和土体静态液化失稳理论判别准则。通过预测一系列饱和松砂三轴不排水试验结果,验证了所建立的本构模型及判别预测准则的合理性。分析结果表明,静态液化发生于土体硬化阶段,静态液化触发伴随着剪应力达到峰值,其后剪应力降低且孔隙水压力持续增长。进一步地,模拟了充分降解的城市固体废弃物在不排水条件下的应力-应变特性,并预测到了潜在失稳线及静态液化触发点。

Theoretically predicting instability of static liquefaction of saturated soils

By using state-dependent yield function and dilatancy function, a state-dependent non-associated elasto-plasticity hardening model is proposed to simulate the undrained behaviors of saturated soils with different initial densities and confining pressures. According to the second-order work theory, the criteria for potential instability and static liquefaction of saturated soils are proposed. The proposed model and criteria were employed to predict a series of undrained triaxial tests on loose sands. The results showed that the static liquefaction occurs at the hardening stage before the plastic limit, the onset of static liquefaction accompanies with the peak of shear stress; and then the pore water pressure increases and the shear stress decreases with further loading. The stress-strain relationship of the municipal solid waste under undrained condition was also analyzed; the potential instability line was obtained and the onset of static liquefaction was predicted.