考虑渗透系数变化的非饱和土固结性状分析  

Analysis of consolidation of unsaturated soil with variable permeability coefficient

作　　者：秦爱芳[1] 张九龙[1] 

机构地区：[1]上海大学土木工程系,上海200072

出　　处：《岩土力学》2015年第6期1521-1528,1536,共9页Rock and Soil Mechanics

基　　金：上海教委创新基金(No.13YZ018);上海自然科学基金(No.13ZR1416200);国家自然基金面上项目(No.41372279)

摘　　要：基于Fredlund非饱和土一维固结理论,研究了有限厚度的表面透水透气、底面不透水不透气的线弹性和黏弹性非饱和土地基在加荷随时间指数性变化时的一维固结特性。分别得到了两类地基在固结过程中同时考虑液相、气相渗透系数非线性变化和仅考虑液相渗透系数变化两种情况下的半解析解答。利用典型算例进行计算,分析了不同情况下两类地基中超孔隙水、气压力消散以及地基固结度随时间的变化规律,并与不考虑渗透系数变化时的半解析解计算结果进行了对比。结果发现:固结过程中渗透系数呈非线性变化;只考虑液相渗透系数变化时,超孔隙气压力的消散变化不大,超孔隙水压力的消散加快;气相渗透系数变化对超孔隙气的消散产生明显影响,对超孔隙水压力消散影响不大。同时考虑液相和气相渗透系数变化时,土体中超孔隙水、气压力的消散均有明显变化,土体固结速度也相应加快;分析结果对非饱和土固结的进一步研究具有重要意义。Based on the Fredlund＇s one-dimensional consolidation theory for unsaturated soil, one-dimensional consolidation of unsaturated soil subjected to an exponentially variable vertical load is investigated with a semi-analytical method. Elastic and viseo-elastic soils with a finite thickness are considered while the soil top surface is penetrable and the bottom is impenetrable to water and air. Semi-analytical solutions are obtained for two soils with variable water and gas permeability coefficients and variable water permeability coefficient, respectively. A typical example result is given to analyze the changes of the excess pore-air pressure, excess pore-water pressure and sedimentation rate of soil under different conditions. The semi-analytical solutions are compared with those without considering the variation of permeability coefficient. It is shown that the permeability coefficient changes nonlinearly in the process of consolidation; when considering variable water permeability coefficient only, the dissipation of excess pore-air pressure is trivial, while excess pore-water pressure dissipates quickly; in the other situation, excess pore-air pressure and excess pore-water pressure dissipate significantly; and accordingly the sedimentation rate of soil also speeds up; the variation of gas permeability coefficients can substantially influence dissipation of excess pore-air pressure, with little effect on dissipation of excess pore-water pressure. The results are useful in analyzing the one-dimensional consolidation of unsaturated soils.

关 键 词：非饱和土 渗透系数 半解析解 一维固结 

分 类 号：TU431[建筑科学—岩土工程]