平面应变条件下结构性黄土本构模型试验研究

Experimental study on constitutive models of structural loess under plane strain conditions

黄土在我国分布广泛,且大多都具有显著的结构性,黄土工程中又有许多平面应变问题,深入研究平面应变条件下结构性黄土的本构关系在理论研究及黄土工程应用中显得尤为重要。为了更合理地描述平面应变条件下结构性黄土的应力–应变关系,基于临界状态土力学理论,提出一个能够反映平面应变条件的结构性黄土本构模型。在模型建立过程中,引入结构屈服压力,依据平面应变试验结果直接确定固定屈服面和加载屈服面,并验证选取塑性体应变pv?为硬化参量的合理性,使本构模型更符合工程中土体的实际受力过程。模型中各参数物理意义明确,可由等向压缩试验和平面应变剪切试验求得,通过试验曲线与模型计算曲线的对比可知,所建立的本构模型可以较合理地描述平面应变条件下结构性黄土加载条件下的强度、变形特性,具有很好的应用前景。

Loess is widely distributed in China and is markedly structural.Because of the different plane strain problems existing in loess engineering,further research on the constitutive relation of structural loess under the condition of plane strain is particularly important in theoretical research and engineering application.In order to describe reasonably the stress-strain relationship of structural loess under plane strain state,a constitutive model of structural loess based on the critical state soil mechanics was put forward.In the process of establishing model,the structural yielding pressure was introduced,and the fixed yielding surface and the yielding surface of loading were determined directly from the result of plane strain tests.The rationality of selecting the plastic volumetric strain as the hardening parameter was verified.It is shown that the constitutive model is more consistent with the actual stress path of soil.The physical meanings of the parameters of the constitutive model were well defined.The parameters of the model were obtained from the isotropic test and plane strain shear test.The comparison between the experimental and calculated curves shows that the constitutive model described reasonably the strength and deformation characteristics of structural loess under the plane strain condition.