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深厚软黏土的大变形特性以及土中渗流存在的起始水力坡降已分别为人们所认识,但能考虑起始水力坡降的深厚软土大变形固结理论报道甚少。假定土的体积压缩系数保持不变,渗透系数与孔隙比为平方关系,在拉格朗日坐标系中建立以超静孔隙水压力为变量考虑起始水力坡降的软土大变形固结问题的控制方程及求解条件。利用有限差分法解决了由起始水力坡降所引起的动边界问题,将很小起始水力坡降下(10-5)的差分解与达西渗流定律下解析解对比,验证了差分数值计算结果的可靠性,从而为解决移动边界问题提供了一种有效方法。最后着重分析了量纲一变量R对固结性状的影响及在大、小应变不同几何假定下固结性状的区别,结果表明:R值的大小会影响渗流前锋的最终位置及移动速度、超静孔压的消散速率。R值越大,渗流前锋的移动速度越慢,土中超静孔压消散越慢,残留于土中而不能消散的超静孔压越大,进而导致土体发生的最终沉降量就越小。大变形几何假定下土中超静孔压的消散速率要比小变形几何假定下快,且固结完成时残留于土中不能消散的超静孔压值要比小变形几何假定下小,故计算得到的地基最终沉降量要比小变形几何假定下的计算值大。
The large deformation of deep soft clay and the initial hydraulic gradient of seepage in soil have been recognized respectively. However, there are few reports on the theory of large deformation and consolidation of deep soft clay which can consider the initial hydraulic gradient. Assuming that the volumetric compressibility of soil remains the same and that the permeability coefficient is proportional to the void ratio, a large deformation consolidation problem of soft soil considering initial hydraulic gradient is established in Lagrange coordinate system with excess pore water pressure as variable The governing equations and solving conditions. The finite difference method was used to solve the dynamic boundary problem caused by the initial hydraulic gradient. Compared with the analytic solution under the Darcy flow law, the difference solution of the initial initial hydraulic gradient (10-5) was compared, and the difference numerical calculation The reliability of the results provides an effective way to solve the problem of moving boundary. Finally, the influence of the dimension-variable R on the consolidation behavior and the consolidation behavior under different geometric assumptions of large and small strain are emphatically analyzed. The results show that the value of R affects the final position and velocity of the seepage striker. Static pore pressure dissipation rate. The larger the value of R is, the slower the moving velocity of seepage front is, the slower the dissipation of excess pore pressure in soil is. The larger the excess pore pressure that remains in the soil and can not be dissipated is the smaller the ultimate settlement of soil. Under the assumption of large deformation geometry, the dissipation rate of excess pore pressure in soil is faster than that under the assumption of small deformation, and the value of the excess pore pressure that can not be dissipated in soil after consolidation is smaller than that under the assumption of small deformation geometry The final subsidence obtained is larger than the one assumed under small deformation geometry.