小应变硬化土模型参数的确定与敏感性分析

发布时间：2018-03-28 07:23

本文选题：小应变硬化土模型　切入点：硬化土模型　出处：《地震工程学报》2017年05期

【摘要】：地下工程施工引起的土体扰动区可分为剧烈扰动区、扰动区、微扰动区和未扰动区。为全面反映土体在扰动下的应力路径和力学响应,必须考虑全应变范围的土体特性,尤其是小应变范围内的力学响应,因此对小应变硬化土本构模型关键参数(初始剪切模量和剪应变阀值)的确定方法进行介绍。开展上海典型软土的三轴固结排水剪切试验和固结试验研究,给出确定上海软土小应变硬化土模型(HSSmall)参数的方法,建议采用原位测试的方法确定土体的初始弹性模量。基于土单元数值模拟进行初始弹性模量和剪应变阀值的参数敏感性分析。随着初始弹性模量的增大,初始压缩曲线与卸载-再压缩曲线的斜率均增大。由于对应的回弹模量不变,初始弹性模量与回弹模量的差值增大,应变与偏应力试验曲线的回滞环宽度也随之增大。随着剪应变阀值的增大,初始压缩曲线和再压缩曲线的近似直线段增长,在同样剪应力情况下,土体的应变值减小,土体保持初始弹性模量刚度的区间增大。
[Abstract]:The soil disturbance area caused by underground engineering construction can be divided into severe disturbance zone, disturbance area, micro-disturbance zone and undisturbed area. In order to reflect the stress path and mechanical response of soil under disturbance, the soil characteristics in the full strain range must be considered. Especially the mechanical response in the small strain range, Therefore, the method of determining the key parameters (initial shear modulus and shear strain threshold) of the constitutive model of small strain hardened soil is introduced. The study on the triaxial consolidation drainage shear test and consolidation test of typical soft soil in Shanghai is carried out. A method for determining the parameters of small strain hardening soil model in Shanghai soft soil is given. It is suggested that the method of in-situ measurement be used to determine the initial elastic modulus of soil. Based on the numerical simulation of soil element, the parameter sensitivity analysis of initial elastic modulus and shear strain threshold is carried out. With the increase of initial elastic modulus, The slope of the initial compression curve and the unloading-recompression curve are both increased. The difference between the initial elastic modulus and the rebound modulus increases because the corresponding modulus of springback is constant. With the increase of the shear strain threshold, the approximate straight section of the initial compression curve and the recompression curve increases, and the strain value of the soil decreases with the same shear stress. The interval between the initial elastic modulus and stiffness of the soil is increased.
【作者单位】：上海市岩土地质研究院有限公司;同济大学土木工程学院地下建筑与工程系;同济大学岩土及地下工程教育部重点实验室;
【基金】：上海市科学技术委员会(16DZ1202204) 国家自然科学基金(51378388) 上海市地矿工程勘察院(Gky201605)
【分类号】：TU41

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