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软黏土中渗流存在起始水力坡降的现象已逐渐为人们所认识,但变荷载下考虑起始坡降的软土大变形非线性固结理论还很鲜见。考虑土中渗流存在的起始水力坡降及非线性压缩渗透特性,在拉格朗日坐标系中建立变荷载下以超静孔压为变量的软土大变形非线性固结模型并给出其有限差分解。在此基础上,通过与达西定律下大变形固结半解析解对比分析,验证了解的可靠性。最后着重分析起始水力坡降对软土大、小变形固结性状影响的差异。结果表明,无论采用小变形假定还是采用大变形假定,考虑起始坡降后超静孔压的消散速率及最终沉降量均比达西定律下小。大、小变形假定下起始坡降均会引起超静孔压不能完全消散的现象,且大变形假定下超静孔压残留值要小于其小变形假定下的残留值,致使大变形假定下土层最终沉降量要比其小变形假定下大。起始水力坡降和几何变形假定均会影响固结性状,且起始坡降值无疑影响更明显,故在软黏土中渗流存在的起始水力坡降在固结计算中不容忽视。
The phenomenon of initial hydraulic gradient of seepage in soft clay has gradually been recognized, but the nonlinear large consolidation theory of soft clay considering initial slope gradient under variable load is still rare. Taking into account the initial hydraulic gradient and nonlinear compression infiltration characteristics of seepage in soil, a large nonlinear consolidation model of large soft clay with variable pore water pressure under variable load is established in Lagrange coordinate system. Its finite difference solution. On this basis, by contrast with the semi-analytical solution of large deformation and consolidation under Darcy’s law, the reliability of the solution is verified. At last, the difference between the initial hydraulic gradient and the large and small deformation and consolidation characteristics of soft soil is emphatically analyzed. The results show that regardless of the small deformation assumption or the large deformation assumption, the dissipation rate and final settlement of the excess pore pressure after the initial slope descent are both smaller than those under the Darcy’s law. Large and small deformation under the assumption that the initial gradient will cause ultra-quiet pore pressure can not be completely dissipated phenomenon, and the large deformation under the assumption of excess pore pressure residual value is smaller than the small deformation under the assumption that the residual value, resulting in large deformation under the assumption The final subsidence of soil is larger than its small deformation assumption. The initial hydraulic gradient and geometric deformation assumption will affect the consolidation behavior, and the initial slope decline undoubtedly affect the more obvious, so the initial hydraulic gradient of seepage in soft clay in the consolidation calculation can not be ignored.