小应变硬化土模型参数的确定与敏感性分析  

Determination and Sensitivity Analysis of the Parameters of Hardening Soil Model with Small Strain Stiffness

作　　者：谢东武 管飞[1] 丁文其 XIE Dongwu;GUAN Fei;DING Wenqi(Shanghai Institute of Geotechnical Engineering, Co., Ltd., Shanghai 200072, China;Department of Geotechnical Engineering, College of Civil Engineering, Tongji University, Shanghai 200092, China;Key Laboratory of Geotechnical and Underground Engineering of the Ministry of Education,Tongji University, Shanghai 200092, China)

机构地区：[1]上海市岩土地质研究院有限公司,上海200072 [2]同济大学土木工程学院地下建筑与工程系,上海200092 [3]同济大学岩土及地下工程教育部重点实验室,上海200092

出　　处：《地震工程学报》2017年第5期898-906,共9页China Earthquake Engineering Journal

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)

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。Geotechnical construction disturbs soil mass,destructs soil fabrics,reduces soil strength,and causes soil deformation,all of which can result in the deformation and destruction of adjacent buildings.According to the value of soil shear strain,the soil surrounding a construction site can be divided into:strongly disturbed zone,disturbed zone,micro-disturbed zone,and undisturbed zone.Therefore,a soil constitutive model needs to consider the small strain characteristics and disturbance characteristics of the soil.Methods for determining key parameters of a hardening soil model with small strain stiffness(HS-Small model),including initial shear modulus and threshold shear strain,have been presented and analyzed.Drained triaxial tests andoedometertests were performed on typical soils in Shanghai,and the corresponding modelparameterswere determined.The in situ testing methods are recommended fordeterminingthe initial elastic modulus of soils.Sensitivity analysis of the HS-Small model parameters,including initial shear modulus and threshold shear strain,revealed that the initial slope of the compression curve and the unloading-recompression curve increased with the increase of the initial elasticmodulus.With increasing threshold shear strain,both the approximate straight segments of thecompressioncurve and the unloading-recompression curve lengthened.Under same shear stress conditions,the shear strain of the soil decreased,while the interval range of the initial elastic modulus of the soil constantly increased.

关 键 词：小应变硬化土模型 硬化土模型 初始剪切模量 剪应变阈值 

分 类 号：TU41[建筑科学—岩土工程]