循环荷载下重塑弱膨胀土滞回曲线形态特征定量研究  

Quantitative research on morphological characteristics of hysteretic curves of remolded weak expansive soil under cyclic loading

作　　者：庄心善 赵汉文 王俊翔 黄勇杰 胡智 ZHUANG Xin-shan;ZHAO Han-wen;WANG Jun-xiang;HUANG Yong-jie;HU Zhi(College of Civil Engineering and Architecture,Hubei University of Technology,Wuhan,Hubei 430068,China)

机构地区：[1]湖北工业大学土木建筑与环境学院,湖北武汉430068

出　　处：《岩土力学》2020年第6期1845-1854,共10页Rock and Soil Mechanics

基　　金：国家自然科学基金(No.51708190)。

摘　　要：以重塑弱膨胀土为研究对象,利用GDS动静态真三轴仪采用分级、单级加载方式对土体进行循环动荷载试验,研究不同围压、频率、固结应力比下土体滞回曲线演化规律。采用滞回曲线形态特征(包围的面积S、长轴斜率k、相邻滞回曲线中心间距d及不闭合程度εp)对土体滞回曲线进行定量描述。试验结果表明:膨胀土滞回曲线的S、d、εp随动应力幅值增大呈非线性增大,随围压、频率、固结应力比的增大而减小;k随动应力幅值的增大呈对数关系衰减,随围压、频率、固结应力比的增加而增大;单级循环荷载下膨胀土滞回曲线εp、d、S均随振次的增加呈非线性衰减,出现循环蠕变现象,分级加载历史对膨胀土滞回曲线的影响较小。A series of cyclic triaxial tests is conducted by GDS apparatus to investigate the effects of confining pressure, loading frequency, consolidation stress ratio on the hysteretic curves of the remolded weak expansive soil under multi-step loadings and single-step loadings respectively. Morphological characteristics of hysteretic curves are quantitatively described by three parameters, namely, the area S of the hysteretic curve, the slope of curve k, center offset distance d of adjacent hysteretic curves, and the degree of closure εp. The results show that the S, d and εp of the hysteretic curve of weak expansive soils increase nonlinearly with the increase of dynamic stress amplitude, while decrease with the increase of confining pressure, frequency and consolidation stress ratio. The k decreases logarithmically with the increase of dynamic stress amplitude, and increases with the increase of confining pressure, loading frequency and consolidation stress ratio. Hysteretic curves of weak expansive soil are approximately parallel under single-step loading. The parameters of εp, d and S decrease nonlinearly with the increase of loading cycle, which reflects the phenomenon of cyclic creep. The multi-step loading history has a slight influence on the hysteretic curve of weak expansive soil.

关 键 词：膨胀土 循环动荷载 固结应力比 滞回曲线 循环蠕变 

分 类 号：TU443[建筑科学—岩土工程]