基于流固耦合特性的非饱和膨胀土变形仿真计算

Simulation analysis of deformation for unsaturated expansive soils based on fluid-solid coupling characteristics

在考虑膨胀土的非饱和土特性基础上,基于有效应力原理的单变量理论推导非饱和膨胀土弹塑性本构模型,选用适用的土-水特征曲线方程和非饱和土渗透系数方程,根据流固耦合力学的理论与方法,将膨胀土吸水膨胀或失水收缩过程视为一个动态耦合作用过程,建立渗流-变形耦合分析模型。该模型考虑流固耦合作用引起的孔隙比和渗透系数变化(包括有效应力的影响),并根据边界孔隙水压(或基质吸力)的变化模拟膨胀土体的吸水和失水过程。通过对膨胀土样室内有荷膨胀试验的渗流、变形过程的仿真模拟验证仿真计算模型的有效性和正确性。研究结果表明:采用该仿真计算模型对膨胀土的变形(膨胀或收缩)进行计算和预测可取得较好结果。

An elastic-plastic constitutive model for unsaturated expansive soil was derived with single variable theory in effective stress principle,which includes the unsaturated characteristics of the soil.Appropriate soil-water character curves and permeability coefficient equation were selected in derivation.The swelling or shrinking behavior of expansive soils was treated as a coupling dynamic process according to the theory and method of fluid-solid coupling mechanism,from which a seepage-deformation coupling model was established.This model considers the changes of void ratios and permeability parameters（including the influence of effective stresses） induced by fluid-solid coupling effect and moreover,and the absorption and losing of water of expansive soils were simulated by setting boundary void water pressure（or matrix suction）.The reliability and correctness of the proposed model were verified by laboratory loading test for expansive soil in terms of seepage and deformation.The result indicates that the numerical simulation is able to well calculate and predict the expansive soils（swelling or shrinking） with good accuracy.