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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 one-dimensional consolidation theory of Fredlund unsaturated soils, the one-dimensional consolidation characteristics of linear elastic and viscoelastic unsaturated soils with extremity permeable and permeable surfaces of finite thickness under the exponential change of loading with time were studied. . Two kinds of semi-analytical solutions are obtained for the two kinds of foundations in the consolidation process, which consider both the nonlinear changes of the liquid and gas permeability coefficients and the changes of the permeability coefficient of the liquid. The typical examples are used to calculate the variation law of excess pore water, pressure dissipation and the degree of consolidation of foundation over time under different conditions, and compared with the results of semi-analytical solutions without considering the variation of permeability coefficient . The results show that the permeability coefficient changes nonlinearly during the consolidation process. When only the permeability coefficient of the liquid phase changes, the dissipation of the excess pore pressure does not change much and the dissipation of excess pore water pressure accelerates. Dispersion had a significant impact on the dissipation of excess pore water pressure has little effect. Considering the changes of permeability coefficient of liquid and gas phases, the dissipation of excess pore water and gas pressure in soil significantly changes, and the consolidation speed of soil increases correspondingly. The further study on the consolidation of unsaturated soil is of great significance.