考虑应力路径的软黏土小应变特性试验研究  

Experimental Study on the Small-strain Characteristics of Soft Clay Considering Stress Paths

作　　者：李泉 吴楠[3] 肖军华[1,2] Li Quan;Wu Nan;Xiao Junhua(Key Laboratory of Road and Traffic Engineering of Ministry of Education,Tongji University,Shanghai 201804,P.R.China;Shanghai Key Laboratoryr of Rail Infrastructure Durability and System Safety,Tongji University,Shanghai 201804,P.R.China;School of Civil Engineering,Beijing Jiaotong University,Beijing 100044,P.R.China)

机构地区：[1]同济大学道路与交通工程教育部重点实验室,上海201804 [2]同济大学上海市轨道交通结构耐久与系统安全重点实验室,上海201804 [3]北京交通大学土木建筑工程学院,北京100044

出　　处：《地下空间与工程学报》2021年第5期1486-1494,共9页Chinese Journal of Underground Space and Engineering

基　　金：国家重点研发计划(2017YFB1201204)。

摘　　要：以苏南地区原状软黏土经K_(0)固结形成的试样为对象,利用配备了弯曲元系统和局部位移测量系统的GDS应力路径三轴测试系统,研究了小应变范围内应力路径转角θ对剪切模量衰减曲线以及阈值剪应变(γ_(0.7))的影响。试验结果表明,土体的初始剪切模量G_(0)值与初始固结应力大小呈正相关关系,并可表示为与孔隙比e、平均有效应力p’相关的函数关系式。土体的剪切模量在10^(-6)~10^(-3)的应变范围内随着剪应变的增加而逐渐衰减,并表现出和试验应力路径与近期应力历史间夹角θ的相关性:应力路径对衰减曲线的影响随着应力路径转角θ的增大逐渐增大,当两者完全相反时,其影响最大。在K_(0)固结条件下,应力路径转角θ对γ_(0.7)的影响大于初始固结平均有效应力p’,同时γ_(0.7)值随着应力路径转角θ的增大而逐渐增大。The test object was undisturbed soil derived from southern Jiangsu after K_(0) consolidation.Using GDS stress path triaxial system equipped with bender element and local displacement measurement system,the effect of stress path rotation angleθon shear stiffness decay curve and threshold shear strain(γ_(0.7))under small strain were studied.The results of this study show that the initial value of shear modulus G_(0) increased along with the consolidation stress,and G_(0) can be expressed as a functional relationship related to void ratio e and the mean effective stress p’.The shear modulus of soil decreases with the increase of shear strain under small strain related to the angleθbetween trail stress path and recent stress history.The effect of stress path on decay curve increases along with the stress path rotation angleθ.If the two directions are entirely reverse,the effect is largest.The effect of the angleθon γ_(0.7) is larger than the mean effective stress p’,and the value of γ_(0.7) increases along with theθ.

关 键 词：软黏土 应力路径转角 小应变特性 初始剪切模量 刚度衰减 阈值剪应变 

分 类 号：TU411[建筑科学—岩土工程]