考虑气相压力变化和偏应力影响的非饱和土本构模型  

New model for unsaturated soils considering variation of gas pressure and shear stress

作　　者：刘艳[1,2] 赵成刚[1] 蔡国庆[1] 李舰[1] 

机构地区：[1]北京交通大学土建学院,北京100044 [2]中国科学院武汉岩土力学研究所,湖北武汉430071

出　　处：《岩土工程学报》2011年第5期754-761,共8页Chinese Journal of Geotechnical Engineering

基　　金：国家自然科学基金项目(51078019);国家重点基础研究发展计划基金项目(2010CB732100);北京市自然科学基金项目(8112024)

摘　　要：基于连续介质土力学的本构模型框架,提出了一个三轴应力状态下的非饱和土本构模型。与非饱和土中的双应力变量不同,根据非饱和土功的表达式,选择广义有效应力、修正吸力和气体压力作为模型的应力状态变量。模型中考虑了气相压力变化对土体变形的影响,给出了固-液-气三相耦合的本构方程。固相采用了非相关联流动法则,并在固相硬化方程中考虑了液相和气相的影响。液相方程利用土水特征曲线描述,并考虑了塑性体应变的影响。气相方程的建立利用了Boyle定律和Henry定律,给出了受固相和液相变形影响的气相方程。最后建立了非饱和土弹塑性增量方程。利用已有的试验数据对模型进行了验证,并将考虑气相影响与未考虑气相影响的预测结果进行了对比。Based on the constitutive framework of unsaturated soils established by the continuum porous medium soil mechanics,an elastoplastic model for unsaturated soils in triaxial stress state is formulated.According to the work expression of unsaturated soils,three stress variables are needed in describing the model： generalized effective stress,modified suction and gas pressure.The gas effect is considered and the constitutive equation considering solid-liquid-gas effect is developed.In the solid phase,a non-associated flow flue is adopted.The plastic change of the degree of saturation and gas strain,representing the influence of the historical evolution of liquid and gas effect respectively,are incorporated in the hardening equations.The soil water characteristic curve is introduced as the liquid constitutive equation,in which the plastic volumetric strain is incorporated to reflect the influence caused by skeleton deformation.Based on the Boyle law and the Henry law,a gas constitutive equation which is affected by the solid and liquid phases is derived.Model predictions are compared with the existing test data,showing that the model agree well with the test data.Comparisons between the model and the one without gas effect are also given.

关 键 词：非饱和土 本构方程 气相影响 

分 类 号：TU43[建筑科学—岩土工程]