冻融循环对粉质黏土力学性质的影响及邓肯-张模型  

Influence of Freeze-thaw Cycling on Mechanical Properties of Silty Clay and Ducan-Chang Constitutive Model

作　　者：胡田飞 刘建坤[1,2] 常丹 房建宏[2] 徐安花 HU Tian-fei1,2,3 , LIU Jian-kun1,2 , CHANG Dan1,2 , FANG Jian-hong2 , XU An-hua2(1. School of Civil Engineering, Beijing Jiaotong University, Beijing 100044, China; 2. Transportation Industry Laboratory of Highway Construction and Maintenance Technology in Permafrost Regions Qinghai Research Observation Base, Qinghai Research Institute of Transportation, Xining 810000, Qinghai, China; 3. School of Civil Engineering, Shijiazhuang Tiedao University, Shijiazhuang 050043, Hebei, Chin)

机构地区：[1]北京交通大学土木建筑工程学院,北京100044 [2]青海省交通科学研究院多年冻土地区公路建设与养护技术交通行业重点实验室--青海研究观测基地,青海西宁810000 [3]石家庄铁道大学土木工程学院,河北石家庄050043

出　　处：《中国公路学报》2018年第2期298-307,共10页China Journal of Highway and Transport

基　　金：中央高校基本科研业务费专项资金项目(C17JB00520);国家自然科学基金项目(51378057);交通运输部应用基础研究计划(重点平台)项目(2014319363200)

摘　　要：为了描述冻融循环下压实黏性土不排水剪切性状的变化规律,建议了一种能够反映冻融循环影响的修正邓肯-张模型。首先,以青藏高原粉质黏土为对象,进行一系列冻融循环试验和常规不固结不排水三轴压缩试验。然后,基于邓肯-张双曲线模型,通过三轴压缩试验得到应力-应变关系,确定邓肯-张双曲线模型参数随冻融循环次数的变化规律及相应的回归关系。最后,根据模型参数的函数表达式,建立以冻融循环次数为影响因子的修正邓肯-张模型,并编制该修正模型的计算程序。结果表明:粉质黏土试样的应力-应变曲线形式基本呈应变硬化型,破坏强度随冻融循环次数的增加而逐渐减小,冻融循环劣化作用随围压的增加而逐渐减弱;模型参数中,抗剪强度指标、初始切线模量、极限偏应力和常数K均随着冻融循环次数的增加呈逐渐减小的变化规律,可以采用Logistic函数进行拟合;破坏比随着冻融循环次数的增加呈逐渐增大的变化规律,可以采用ExpAssoc函数进行拟合;常数n随着冻融循环次数的增加呈先减小、后增大的变化规律,可以采用三次多项式函数进行拟合;模型计算结果与试验结果对比表明,两者得到的应力-应变曲线基本吻合,说明该模型可以用来描述粉质黏土变形和强度特性在冻融循环下的劣化特征。In order to describe the change rule of the undrained shear behavior of compacted clay under the freeze-thaw cycling, an improved constitutive model which reflected the influence of the freeze-thaw cycling based on the traditional Duncan-Chang model was put forward. A set of freeze-thaw cycling tests were conducted on samples which were made of silty clay from the Qinghai-Tibet Plateau, and unconsolidated undrained triaxial tests were subsequently carried out on the freeze-thaw expansive samples. Besides, the change rule of the parameters of Duncan- Chang constitutive model with the number of freeze-thaw cycles and its corresponding regression relation were determined b dint of triaxial compression y stress-strain relations. The stress-strain relations were obtained by ests, on the basis of Duncan-Chang hyperbolic model. Finally, based on the functions of model parameters number of freeze-thaw cycles as in calculation program for the improve d the improved Duncan-Chang constitutive model taking the uence factors was established, whilst a corresponding Duncan-Chang constitutive model was drawn up. The results show that the stress-strain curves of samples with silty clay are curves of strain hardening type. The failure strength decreases with the increases of the number of freeze-thaw cycles, and the deterioration effect of the freeze-thaw cycling gradually decreases with the increase of the confining pressure. Among the Duncan-Chang model parameters, the shear strength index, initial tangent modulus, ultimate deviatoric stress, and K all keep decreasing by the increasing number of freeze-thaw cycles, and all parameters can be fitted by the Logistic function. The failure ratio keeps increasing with the increasing number of freeze-thaw cycles, and can be fitted by the ExpAssoc function. The n decreases at first and then increases with the increase of freezethaw cycles, and it can be fitted by cubic polynomial function. The calculated stress-strain curves are identical with measured ones, so this improved model is a

关 键 词：道路工程 粉质黏土 三轴试验 冻融循环 不排水剪切性状 修正邓肯-张模型 

分 类 号：U416.14[交通运输工程—道路与铁道工程]