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成层土在工程中很常见,研究降雨过程中成层非饱和土的渗流-变形耦合对非饱和土土力学的发展具有重要的意义。由流体质量守恒,Darcy定律和Lloret等的非饱和土本构模型可得成层非饱和土渗流-变形耦合的控制方程。采用Gardner的非饱和土的渗透系数公式以及Boltzman模型,基于Laplace变换得到耦合方程的解析解。解析及其参数分析表明,渗流和变形耦合是具有时间效应的。与吸力变化相关的土的模量F,对成层土的孔隙水压力分布有明显影响。两层土的F差异越大,孔隙水压力消散得越慢,耦合效应越不显著。增大表层土的F值有利于降低耦合效应。成层土饱和体积含水率变化对吸力变化产生有限的影响。
Stratified soil is very common in engineering. It is of great significance to study the seepage-deformation coupling of unsaturated soils in the process of rainfall for the development of unsaturated soil mechanics. From the conservation of fluid mass, Darcy’s law and the unsaturated soil constitutive model of Lloret et al., A governing equation for seepage-deformation coupling of layered unsaturated soils can be obtained. Using Gardner ’s formula of permeability coefficient of unsaturated soil and Boltzman model, the analytic solution of the coupled equation is obtained based on Laplace transform. Analysis and analysis of its parameters show that seepage and deformation coupling have time effect. The modulus of soil F, which is related to the change of suction, has obvious influence on the pore water pressure distribution of stratified soil. The larger the difference of F in two layers of soil, the slower the dissipation of pore water pressure, the less obvious the coupling effect. Increasing the F value of the topsoil helps to reduce the coupling effect. The change of saturated volumetric water content of layered soil has a limited impact on the change of suction.