初始剪应力与频率对超固结软土变形试验研究  

Deformation of overconsolidated soft clay considering initial shear stress and frequency

作　　者：王军[1] 蔡袁强[1,2] 高玉峰[1,3] 

机构地区：[1]温州大学建筑与土木工程学院,浙江温州325035 [2]浙江大学岩土工程研究所,浙江杭州310027 [3]河海大学岩土工程科学研究所,江苏南京210098

出　　处：《振动工程学报》2010年第3期260-268,共9页Journal of Vibration Engineering

基　　金：国家自然科学基金资助项目(50808145;50979096;50908212);浙江省自然科学基金杰出青年团队项目(R1080819);浙江省自然科学基金项目(Y1090105);温州市科技计划项目(S20080046;S20090006);浙江省建设厅科研项目(08Z027);浙江省高校优秀青年教师资助计划项目

摘　　要：通过GDS循环三轴试验系统,对循环荷载作用下杭州饱和软粘土的动应变变化规律进行了研究,分析了循环应力比、初始剪应力、振动频率及超固结比等因素对动应变的影响。研究结果表明:随着循环应力比的增加,动应变发展速度增快。循环荷载作用下饱和软粘土存在临界循环应力比,通过动应变与循环次数关系曲线也可以确定其值大小。在循环初期,应变率较大,随着循环时间的增加,应变率逐渐减小。随着循环应力比的增加,应变率增加。振动频率对应变-循环次数关系影响明显,随着频率的增加,动应变减小;然而,振动频率对动应变-时间与应变率-时间关系影响不明显。随着初始剪应力的增大,动应变发生较大幅度的增加。初始剪应力对应变率具有显著影响;随着初始剪应力的增加,应变率增加。在对数坐标下,应变率随时间线性减小。随着超固结比的增加,动应变及应变率均减少。在上述试验基础上建立了应变率与时间关系表达式,通过积分得到了循环荷载作用下考虑初始剪应力、振动频率及超固结比影响的杭州饱和软粘土的累积塑性应变模型。The dynamic strain of saturated soft clay in Hangzhou under cyclic loading is researched by GDS cyclic triaxial system.The effect of cyclic stress ratio,initial shear stress,frequency and overconsolidated ratio on dynamic strain is analyzed.It is observed that the dynamic strain increases with the increase of cyclic stress ratio.There is critical cyclic stress ratio of soft clay under cyclic loading.The value of critical cyclic stress ratio can also be obtained by dynamic strain and cyclic number of cycles curves.At the beginning of cyclic loading,the strain rate is bigger and then it decreases with the time.With the increase of cyclic stress ratio,the strain rate increases.The frequency influences the relationship between strain and cyclic number significantly and the dynamic strain decreases with the increase of frequency.However,the effect of frequency on dynamic strain and time and strain rate and time curves is indistinct.With the increase of initial shear stress,both the dynamic strain and strain rate increases.With the increase of overconsolidated ratio,both the dynamic strain and strain rate decreases.It shows linear relationship between strain rate and time at log-scale.Based on the test results,the empirical equation between strain rate and time,and accumulative plastic model of soft clay under cyclic loading by integration are obtained.

关 键 词：循环荷载 频率 初始剪应力 循环应力 超固结比 

分 类 号：TU411.8[建筑科学—岩土工程]