循环荷载作用下漫灌区粉质黏土的动力特性研究  

Dynamic characteristics of silty clay in flood irrigation areas under cyclic loading

作　　者：王梦洁 张莎莎[1,2] 杨晓华[1,2] 张超[1] 晏长根[1,2] WANG Meng-jie;ZHANG Sha-sha;YANG Xiao-hua;ZHANG Chao;YAN Chang-gen(School of Highway,Chang’an University,Xi’an,Shaanxi 710064,China;Xi’an Key Laboratory of Geotechnical Engineering for Green and Intelligent Transport,Chang’an University,Xi’an,Shaanxi 710064,China)

机构地区：[1]长安大学公路学院,陕西西安710064 [2]长安大学西安市绿色智慧交通岩土工程重点实验室,陕西西安710064

出　　处：《岩土力学》2025年第4期1215-1227,共13页Rock and Soil Mechanics

基　　金：国家自然科学基金(No.42077265);晋中市科技计划项目(市科发[2022]28号)。

摘　　要：为明确交通荷载作用下漫灌区粉质黏土的动力变形特性,通过开展单样逐级和多样恒定幅值的循环加载动三轴试验,研究了围压、偏压固结比、排水条件、动荷载频率和循环应力比等因素对粉质黏土累积塑性应变和残余动孔压发展规律、滞回曲线演化特性以及软化指数的影响。结果表明:土体在动荷载作用下的累积塑性应变和残余动孔压的发展具有一致性,根据安定性理论可以将试样在不同试验条件下的动力行为划分为塑性安定、塑性蠕变和增量破坏3种典型情况,在试验基本工况下,塑性安定、塑性蠕变和增量破坏3种动力行为的界限循环应力比分别在0.30和0.40附近;处于塑性安定状态不排水试样的滞回特征明显,滞回曲线呈S形,随着加载的进行土体存在刚度退化现象;不排水试样的累积塑性变形小于排水试样,在较低循环应力比下排水和不排水条件土体的软化指数分别稳定在1.15左右和0.91左右;通过灰色关联度分析发现,循环应力比对累积塑性应变和孔压比的影响程度最大,围压对软化指数的影响程度最大;确定了适用于漫灌区粉质黏土的累积塑性应变模型的相关参数,预测效果良好。Dynamic triaxial tests were conducted to clarify the dynamic deformation characteristics of silty clay in flood irrigation areas under cyclic loading,using single-sample stepwise and multiple samples of constant amplitude.The effects of confining pressure,bias consolidation ratio,drainage conditions,dynamic load frequency,and cyclic stress ratio on the development law of cumulative plastic strain and residual dynamic pore pressure,the evolution characteristics of the hysteresis curve,and the change law of softening index of silty clay were studied.The results show that the development of cumulative plastic strain and residual dynamic pore pressure of soil under dynamic load is consistent.According to the stability theory,the dynamic behavior of samples under different test conditions can be divided into three typical cases:plastic stability,plastic creep and incremental failure.Under the basic conditions of this test,the boundary cyclic stress ratios of the three dynamic states of plastic stability,plastic creep,and incremental failure are around 0.30 and 0.40,respectively.The hysteresis characteristics of undrained specimens in the plastic stable state are obvious,and the hysteresis curve shows an S shape.With the progression of loading,soil experiences stiffness degradation.The cumulative plastic deformation of undrained specimens is smaller than that of drained specimens,and the softening index of soil under drained and undrained conditions remains stable at around 1.15 and 0.91,respectively,under lower cyclic stress ratios.Through grey relational analysis,it is found that the cyclic stress ratio has the greatest influence on the cumulative plastic strain and pore pressure ratio.The confining pressure exerts the greatest influence on the softening index.The parameters of the cumulative plastic strain model suitable for silty clay in flood irrigation areas have been determined,and the prediction effect is good.

关 键 词：动三轴试验 粉质黏土 循环应力比 累积塑性应变 软化指数 

分 类 号：TU411.3[建筑科学—岩土工程]