考虑起始坡降双层地基的大应变非线性固结  

Large-strain nonlinear consolidation of double-layered soft clay with threshold gradient

作　　者：李传勋[1] 董兴泉 金丹丹[1] 王玉林 LI Chuan-xun;DONG Xing-quan;JIN Dan-dan;WANG Yu-lin(Faculty of Civil Engineering and Mechanics, Jiangsu University, Zhenjiang, Jiangsu 212013, China;College of Civil Engineering and Architecture, Wuyi University, Wuyishan, Fujian 354300, China)

机构地区：[1]江苏大学土木工程与力学学院,江苏镇江212013 [2]武夷学院土木工程与建筑学院,福建武夷山354300

出　　处：《岩土力学》2018年第5期1877-1884,共8页Rock and Soil Mechanics

基　　金：国家自然科学基金项目(No.51109092);江苏省青年基金项目(No.BK20150512)~~

摘　　要：天然软土成层分布特性及土中渗流存在起始水力坡降的现象已被人们熟知。但变荷载下能同时考虑黏土中起始水力坡降、软土非线性压缩渗透特性及大应变特性的双层地基固结理论还鲜见报道。在拉格朗日坐标系中建立以超静孔压为变量的双层软土地基大应变非线性固结模型并给出其有限差分解。通过与考虑起始水力坡降的单层地基大应变非线性固结数值计算结果对比,验证了差分解的可靠性。着重分析了上、下土层起始坡降无量纲参数R_1、R_2对双层地基固结性状的影响,分析在大应变与小应变假定下双层地基超静孔压消散及固结沉降变形的异同。结果表明:上层土无量纲参数R_1对双层地基固结性状的影响程度较下层土无量纲参数R_2显著;大应变假定下双层地基渗流前锋的下移速度要快于小应变假定下的移动速度;大应变假定下考虑起始水力坡降的双层软土地基超静孔压消散速率要比小应变假定下快,且大应变假定下考虑起始水力坡降的双层地基最终沉降量要比小应变假定下大。Layered distribution of natural soft soils and the threshold gradient of the flow in soils have been gradually recognized. However, with consideration of the threshold hydraulic gradient and the nonlinear compressibility and permeability, the theory of large-strain consolidation of double-layered soil has rarely been reported in the literature so far. In this study, a model for large-strain nonlinear consolidation of double-layered soil is developed in Lagrangian coordinate by employing the excess pore water pressure as a variable. Meanwhile the corresponding finite difference solution for this model are provided. The numerical solution for the proposed model is verified by comparing with the numerical solution of large-strain nonlinear consolidation of a single-layered soil with threshold gradient. Finally, the influences of dimensionless parameters R1, Rz on consolidation behaviors are analyzed. The differences of the dissipation of excess pore water pressure, and the differences of the consolidation settlement under large- and small-strain conditions are investigated. The results show that the influences of R1 on consolidation behavior of double-layered soil are more evident than that of R2; the moving speed of seepage flow front of double-layer soiled under large-strain assumption is faster than that under small-strain assumption; the dissipation rate of excess pore pressure under large-strain assumption is faster than that under small-strain assumption, and the settlements of double-layered soil with threshold gradient under large-strain assumption is larger than that under small-strain assumption.

关 键 词：双层地基 起始水力坡降 大变形固结 非线性固结 有限差分 

分 类 号：TU433[建筑科学—岩土工程]