粉质黏土强度特性应变速率效应的试验研究  

Experimental Study on Strain Rate Effect of Strength Characteristics of Silty Clay

作　　者：胡田飞 刘建坤[1] 刘振亚[1] 刘昕 

机构地区：[1]北京交通大学土木建筑工程学院,北京100044 [2]石家庄铁道大学土木工程学院,河北石家庄050043 [3]青海大学地质工程系,青海西宁810016

出　　处：《铁道学报》2018年第2期132-140,共9页Journal of the China Railway Society

基　　金：交通运输部应用基础研究项目(2014319363200);国家自然科学基金(51378057;41371081)

摘　　要：应变速率是影响土体强度特性的主要因素之一。通过粉质黏土在不同应变速率和围压下的三轴试验,分析应变速率对应力-应变关系的影响机理。结果表明:应变速率效应受到土骨架黏滞性、固结和孔隙压力的综合影响,各因素对围压和应变速率的响应不同。高围压和低应变速率有利于固结,低围压和高应变速率会增大黏滞性作用比例,高围压和高应变速率会增强孔隙压力影响。峰值强度在高围压下随应变速率的增大先减小、后增大、再减小,在低围压下则先减小、后增大,应变速率临界值随围压的增加而增大,应变速率敏感程度随围压的增大而降低。弹性模量在低围压下随应变速率单调增大,在高围压下先减小、后增大。可以分别采用线性函数和二次多项式描述应变速率对土体力学和变形参数的影响规律。The strain rate is one of the main factors that affect the strength characteristics of soil aggregate.In order to investigate the influence of strain rate on stress-strain relationship,a series of triaxial tests were conducted on silty clay under different strain rates and confining pressures in this study.The results show that the strain rate effect is affected by consolidation process,soil viscosity,and pore pressure comprehensively,whose response to the confining pressures and strain rate differs with each other.The high confining pressure and low strain rate both benefit the development of consolidation,while the opposite conditions will increase the proportion of viscosity effect.In addition,the increase of confining pressure and strain rate will strengthen the effect of excessive pore pressure.Correspondingly,the peak strength decreases first,and increases subsequently,then decreases again with the increase of strain rate under high confining pressure.However,under low confining pressure,the peak strength decreases first and then increases.Besides,the critical strain rates increase with the increase of confining pressure.The sensitivity of the strain rate decreases with the increase of confining pressure.The elastic modulus increases monotonically with strain rate under low confining pressure,while it decreases first and then keeps increasing under high confining pressure.The influence of strain rate on the mechanical and deformation characteristics of soil can be fitted by the linear function and quadratic polynomial function,respectively.

关 键 词：粉质黏土 应变速率 峰值强度 弹性模量 黏滞性 固结 孔隙压力 

分 类 号：TU43[建筑科学—岩土工程]