考虑起始水力坡降的软土大变形非线性固结分析

发布时间：2018-12-31 19:20

【摘要】：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。
[Abstract]:The phenomenon of initial hydraulic gradient in seepage flow in soft clay has been gradually recognized, but the nonlinear consolidation theory of large deformation of soft soil considering initial slope under variable load is still rare. Considering the initial hydraulic gradient and nonlinear compression seepage characteristics of seepage in soil, a nonlinear consolidation model of soft soil with large deformation under variable load is established in Lagrangian coordinate system and its finite difference decomposition is given. On this basis, the reliability of the solution is verified by comparing it with the semi-analytical solution of large deformation consolidation under Darcy's law. Finally, the effect of initial hydraulic slope on the consolidation behavior of soft soil with large and small deformation is analyzed. The results show that the dissipation rate and the final settlement of the excess pore pressure after considering the initial slope are smaller than those under Darcy's law, regardless of the assumption of small deformation or large deformation. Under the assumption of large deformation and small deformation, the initial slope drop will lead to the phenomenon that the excess static pore pressure can not dissipate completely, and the residual value of the excess static pore pressure under the large deformation assumption is smaller than the residual value under its small deformation assumption. As a result, the final settlement of soil layer under the assumption of large deformation is larger than that under the assumption of small deformation. Both the initial hydraulic gradient and the geometric deformation assumption will affect the consolidation behavior, and the initial gradient value is undoubtedly more obvious, so the initial hydraulic gradient existing in the seepage flow in soft clay can not be ignored in the consolidation calculation.
【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(No.51109092,No.11272137) 中国博士后基金项目(No.2013M530237,No.2014T70479) supported by the National Natural Science Foundation of China(51109092,11272137) the Foundation for Post-doctoral Scientists of China(2013M530237,2014T70479)
【分类号】：TU447;TU433

【相似文献】