考虑粗粒土应变软化特性和剪胀性的本构模型

A Constitutive Model for Coarse Granular Material Incorporating Both Strain Work-softening and Dilatancy

在传统细粒土本构模型的基础上进行了改进,建立了一个能较好地描述粗粒土应变软化特性和剪胀性的弹塑性本构模型.该模型采用双屈服面形式,克服了单屈服面模型存在的一些不足,可同时反映剪切变形和压缩变形机理.模型在应变软化特性描述方面,提出了一个利用残余状态应力比和峰值应力比的应变软化公式,较为合理地反映了粗粒土的应变软化现象.在剪胀性描述方面,考虑了状态转换应力比与初始有效围压的相关性.数值模拟结果与试验结果较为接近,表明该模型描述粗粒土在低围压和相对中高围压下的应变软化特性和剪胀性方面具有一定的优越性.

Based on the traditional constitutive model for cohesionless soil, an elasto-plastic model for coarse granular material is proposed, which can describe both strain worksoftening and dilatancy reasonably. The two yield surfaces model can reflect shear deformation and compression deformation respectively, making up for the deficiency of single yield surface model, and the relativity between phase transformation stress ratio and initial effective pressure is considered when describing the dilatancy of coarse aggregates. A strain work-softening equation including the stress ratios at steady state and peak state is developed,which can express the characteristic of strain work-softening preferably. The numerical simulation agrees well with the data of large-scale triaxial compression test, which proves the model to be of the priority in describing the dilatancy and strain work-softening under low and relatively high confining pressure.