考虑非达西渗流和变荷载影响的软土大变形固结分析

软土中的非达西渗流和大变形特性已为人们所认识,但能考虑土中非达西渗流的软土大变形固结理论还鲜有报道。考虑实际中的变荷载,基于土中的非达西渗流现象在拉格朗日坐标系中建立以超静孔隙水压力为变量的软土一维大变形固结模型。利用有限差分法对所建立的模型进行数值求解,并与特定条件下的解析解对比,以验证数值解的可靠性。最后着重分析非达西渗流模型参数对软土大变形固结性状的影响及大、小应变不同几何假定下非达西渗流固结性状的异同。结果表明非达西渗流模型的参数m及i1值越大,地基的固结速率就越慢;如果小应变固结理论中自重应力的计算也考虑沉积作用,此时尽管软土在大变形几何假定下的固结速率要比小变形假定下快,但大、小应变固结理论计算的地基最终沉降值相等;基于此,鉴于大变形固结理论的复杂性,此种情况下应用小变形代替大变形几何假定所引起的计算误差是可接受的。

Large-strain consolidation of soft clay with non-Darcian flow by considering time-dependent load

The large deformation behavior and the non-Darcian flow in soft clay have been already recognized, however, the theory of large-strain nonlinear consolidation of soft clay with non-Darcian flow has been rarely reported. By considering time-dependent load, a model for one-dimensional large-strain consolidation of soft clay with non-Darcian flow law is developed in the Lagrangian coordinate, in which the excess pore water pressure serves as a variable. The finite difference method is adopted to obtain numerical solutions for this model, and a comparison between the numerical solutions and analytical solutions which are obtained on some specific conditions is presented to verify the reliability of the numerical solutions. Finally, the influence of non-Darcian flow on large-strain consolidation behavior and the difference in consolidation behavior of clay with non-Darcian flow between large-strain and small-strain conditions are investigated. The results show that the consolidation rate may decrease with an increase in the value of m or i₁. If the self-weight stress for the small-strain consolidation with non-Darcian flow is also calculated by considering its sedimentation, the final settlement of clay layer under large-strain condition is the same as that in the small-strain case, although the consolidation rate under large-strain condition is faster than that under small-strain condition. As a result, due to the complexity of the large-strain condition, the error in settlement curve induced by the replacement of large-strain condition by small-strain condition can be acceptable in this case.