变荷载下双层地基一维非线性固结近似解析解

Approximate analytical solutions for one-dimensional nonlinear consolidation of double-layered soil under time-dependent loading

目前考虑土体非线性压缩及渗透特性的双层地基非线性固结解均假定土体固结系数保持不变,能反映固结系数变化的双层地基非线性固结解还很鲜见。引入经典的e-lgσ’和e-lgkv非线性关系描述土体的非线性压缩、渗透特性,在假定双层地基上、下土层压缩指数与渗透指数比值Cci/Cki相等且不等于1的基础上,得到变荷载下考虑土体固结系数变化的双层地基一维非线性固结近似解。该解答在Cc/Ck→1条件下可退化为已有的Cc/Ck=1时双层地基一维非线性固结解。基于此解探讨了双层地基上、下土层参数的相对比值对非线性固结性状的影响。结果表明:单面排水条件下Cc/Ck越小,下层土与上层土的相对压缩性越低、相对渗透性越高,则双层地基非线性固结速率越快;减小Cc/Ck值,增加双层地基中压缩性小、渗透性高的土层的厚度,会加快地基的固结速率。

At present,it is assumed that the consolidation coefficient of the soil remains constant for the nonlinear consolidation solutions of the double-layered soil considering the nonlinear compression and permeability of soil.There are few studies on the nonlinear consolidation solutions of double-layered soil considering the variation of consolidation coefficient.The classical e-lgσ’ and e-lgkv nonlinear relationships are introduced to describe the nonlinear compression and permeability characteristics of soil.Based on the assumption that the ratios Cci/Cki of compression index and penetration index in both layers are the same and not equal to 1,the approximate solutions for one-dimensional nonlinear consolidation of the double-layered soil are obtained considering the variation of consolidation coefficient and time-dependent loading.Under the condition of Cc/Ck→1,the solutions in this study can be degenerated to the existing one-dimensional nonlinear consolidation solutions of double-layered soil when Cc/Ck=1.The influence of relative parameter ratios of the lower layer to the upper layer in double-layered soil on the nonlinear consolidation behavior finally is analyzed.The results show that,under the condition of single drainage,the nonlinear consolidation rate of the double-layered soil increases with the decreasing Cc/Ck,the reducing relative compressibility,or the increasing relative permeability.When Cc/Ck reduces or the thickness of the soil layer with low compressibility and high permeability increases,the consolidation rate of double-layered soil increases.