变荷载下考虑起始水力坡降与连续排水边界的固结解  

Analytical solution of consolidation considering initial hydraulic gradient and continuous drainage boundary under variable load

作　　者：李全军 陈余 金丹丹[2] 李传勋[2] LI Quanjun;CHEN Yu;JIN Dandan;LI Chuanxun(The Third Geology Group of Jiangsu Geology&Mineral Exploration Bureau,Zhenjiang 212001,Jiangsu,P.R.China;Faculty of Civil Engineering and Mechanics,Jiangsu University,Zhenjiang 212013,Jiangsu,P.R.China)

机构地区：[1]江苏省地矿局第三地质大队,江苏镇江212001 [2]江苏大学土木工程与力学学院,江苏镇江212013

出　　处：《土木与环境工程学报（中英文）》2023年第1期122-134,共13页Journal of Civil and Environmental Engineering

基　　金：国家自然科学基金(51878320)。

摘　　要：采用连续排水边界的必要性及软黏土中水的渗流存在着起始水力坡降(i0)的现象已逐渐被认识,但变荷载下同时考虑连续排水边界条件和起始水力坡降的一维固结解析解还鲜见报道。针对外荷载随时间逐渐增加的实际情况,建立变荷载下同时考虑连续排水边界和起始水力坡降的固结模型。采用傅里叶变换及拉普拉斯变换获得模型的近似解析解,利用该解答分析动边界移动规律、超静孔隙水压力随时间的消散规律及平均固结度的增长规律。结果表明:在加载速率不变的情况下,起始水力坡降下排水面透水情况对固结性状的影响与其在达西定律下相同,透水情况越好,孔压消散速率越快;透水情况越差,超静孔隙水压力消散速度越慢。与完全透水边界条件下相比,连续排水条件下起始水力坡降i0对固结性状影响无明显改变,i0越大,移动边界到达土层底部的时间越长,固结完成时土中残留的超静孔压越大,按孔压定义的平均固结度越小;i0值越小,移动边界到达土层底部的时间越短,固结完成时土中残留的超静孔压越小,按孔压定义的平均固结度越大。在起始水力坡降和边界排水条件不变的情况下,随着加载时间的增加,超静孔隙水压力峰值越小,超静孔隙水压力达到峰值的时间越长,但加载时间对超静孔压残留值及按孔压定义的最终平均固结度无影响。It has been gradually recognized of the existing of initial hydraulic gradient(i0)during water seepage in soft clay and the necessity of considering continuous drainage boundary is being accepted more and more.However,the analytical solution of one-dimensional consolidation under variable load,considering both continuous drainage boundary condition and initial hydraulic gradient has rarely been reported.Based on the actual situation that the external load increases with time,taking variable load into account,a consolidation model considering both continuous drainage boundary and initial hydraulic gradient is established.The approximate analytical solution of the one-dimensional consolidation model is obtained by using Fourier transform and Laplace transform,from which,the moving law of dynamic boundary,dissipation law of excess pore water pressure as well as the growth characteristics of average consolidation degree are analyzed.The results show that,with the same loading rate,the influence of permeability of drainage surface under initial hydraulic gradient on consolidation behavior is just the same with that according to Darcy’s law.The better the permeability is,the faster the dissipation rate of pore water pressure comes,and conversely,the worse the permeability is,the slower the dissipation rate of excess pore water pressure becomes.The effect of initial hydraulic gradient on consolidation behavior under continuous drainage boundary presents consistent with that under fully permeable boundary,of which the fact is,a larger value of i0may lead to,larger residual excess pore pressure when consolidation is completed,and smaller average degree of consolidation defined by pore pressure.On the other side,the smaller value of i0is,the shorter time it takes for the moving boundary reaching to the bottom of soil layer,the smaller the residual excess pore pressure becomes,and the larger the average degree of consolidation defined by pore pressure is.When under the same initial hydraulic gradient case and boundary dra

关 键 词：变荷载 连续排水边界 起始水力坡降 移动边界 解析解 

分 类 号：TU433[建筑科学—岩土工程]