基于起始水力坡降的软土一维大变形固结分析

发布时间：2018-01-17 20:40

本文关键词：基于起始水力坡降的软土一维大变形固结分析　出处：《岩石力学与工程学报》2015年S1期 　论文类型：期刊论文

【摘要】：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。
[Abstract]:The characteristics of 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 consolidation theory of deep soft soil with large deformation considering the initial hydraulic gradient, assuming that the volume compression coefficient of the soil remains constant, and the permeability coefficient is square to the porosity ratio. In Lagrangian coordinate system, the governing equation and solving conditions of consolidation problem of soft soil with large deformation considering initial hydraulic gradient with excess pore water pressure as variable are established. The finite difference method is used to solve the problem induced by initial hydraulic gradient. The moving boundary problem. The difference decomposition under a very small initial hydraulic gradient is compared with the analytical solution under Darcy's seepage law, which verifies the reliability of the difference numerical calculation results. Finally, the influence of dimensional-variable R on consolidation behavior and the difference of consolidation behavior under different geometric assumptions of large and small strain are analyzed. The results show that the value of the ratio R will affect the final position and moving velocity of the seepage front. The larger the dissipation rate of the excess pore pressure is, the slower the moving velocity of the seepage front is, and the slower the dissipation of the excess pore pressure in the soil is. The larger the excess pore pressure which remains in the soil but cannot dissipate, the smaller the final settlement of the soil will be. Under the assumption of large deformation geometry, the dissipation rate of the excess static pore pressure in the soil is faster than that under the small deformation geometry assumption. The value of excess pore pressure which can not be dissipated at the completion of consolidation is smaller than that under the geometric assumption of small deformation, so the calculated final settlement of the foundation is larger than the calculated value under the geometric assumption of small deformation.
【作者单位】：江苏大学土木工程与力学学院;浙江大学滨海和城市岩土工程研究中心;
【基金】：国家自然科学基金项目资助(51109092,51179170) 中国博士后基金特别资助(2014T0479)
【分类号】：TU447
【正文快照】： 1引言软黏土中的渗流在低水力坡降下可能会出现偏离达西定律的现象,S.Hansbo[1]将其统称为非达西渗流。如果完全忽略低水力坡降下的土中渗流,即当土中水力坡降i小于某值i0时,渗流就不会发生;只有水力坡降大于该值时,才会有渗流发生,此时土中渗流就遵循R.J.Miller和D.E.Low[2]

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