圆形应力路径下软黏土的动力特性试验研究  

Experimental study of cyclic behavior of soft clay under circle stress paths

作　　者：王钰轲 万永帅 方宏远[1,2,3] 曾长女 石明生[1,2,3] 吴迪[5] WANG Yu-ke;WAN Yong-shuai;FANG Hong-yuan;ZENG Chang-nü;SHI Ming-sheng;WU Di(College of Water Conservancy&Engineering,Zhengzhou University,Zhengzhou,Henan 450001,China;National Local Joint Engineering Laboratory of Major Infrastructure Testing and Rehabilitation Technology,Zhengzhou,Henan 450001,China;Collaborative Innovation Center of Water Conservancy and Transportation Infrastructure Safety Protection,Zhengzhou,Henan 450001,China;College of Civil Engineering and Architecture,Henan University of Technology,Zhengzhou,Henan 450001,China;School of Civil Engineering and Architecture,Qingdao Binhai University,Qingdao,Shandong 266555,China)

机构地区：[1]郑州大学水利科学与工程学院,河南郑州450001 [2]重大基础设施检测修复技术国家地方联合工程实验室,河南郑州450001 [3]水利与交通基础设施安全防护河南省协同创新中心,河南郑州450001 [4]河南工业大学土木建筑学院,河南郑州450001 [5]青岛滨海学院土木建筑学院,山东青岛266555

出　　处：《岩土力学》2020年第5期1643-1652,共10页Rock and Soil Mechanics

基　　金：国家重点研发计划项目(No.2017YFC0405002,No.2019YFC1510803);河南省高等学校重点科研项目(No.20A560021);国家自然科学基金项目(No.51708310,No.51679219);山东省自然科学基金资助项目(No.ZR2017BEE066)。

摘　　要：实际交通荷载作用下,路基土单元内的竖向应力和水平应力大小不断发生变化,剪应力幅值和方向也不断变化,从而导致土体中的应力路径呈现出主应力轴连续旋转的现象。通过GDS空心圆柱扭剪仪模拟类似交通荷载作用下的应力路径,开展不同围压和不同循环应力比下的主应力轴连续旋转试验,旨在研究在交通荷载类轴向纯压缩条件下主应力轴方向连续旋转时循环应力比与围压对原状软黏土的强度、累积应变、回弹应变、软化等因素的影响。试验结果表明:随着孔压的不断累积,原状饱和软黏土试样逐渐软化,轴向模量和剪切模量均随着循环应力比和围压的增加而逐渐降低,并在主应力轴旋转一定的循环次数后达到稳定。当循环应力比较小时,轴向和剪切应力-应变滞回曲线均呈线性,不同主应力轴循环旋转次数下的轴向和剪切应力-应变滞回曲线近乎重合。随着主应力轴循环旋转次数的增加,轴向和剪切应力-应变滞回曲线越来越表现出明显的非线性,不同循环次数下试样的轴向和剪切应力-应变滞回圈不再重合且滞回圈逐渐向x轴倾斜。随着循环应力比的增加,在主应力轴连续旋转初期,轴向模量和剪切模量迅速衰减,且随着循环次数的增加而达到稳定,并且试样的轴向模量和剪切模量达到稳定时的主应力轴连续旋转的循环次数随循环应力比和围压的增大而不断增大。In engineering practices, the vertical stress and horizontal stress in the subgrade soil unit constantly change, and the amplitude and direction of shear stress also constantly change, which lead to continuous rotation of the stress path in the soil. To investigate the influence of the confining pressure and the cyclic stress ratio(CSR) on strength, cumulative strain, resilient strain and softening of natural soft clay when the principal stress axis continuously rotates under pure axial compression of traffic load, the GDS hollow cylinder apparatus(HCA) is used to simulate the stress path under a laboratory-simulated traffic load, and tests of continuous rotation of the principal stress axis under different confining pressures and different cyclic stress ratios are carried out. The testing results show that with the accumulation of pore pressure, the samples of natural saturated soft clay gradually softened. The axial and torsional moduli decreased with increasing CSR and confining pressure and then reached a steady value after a certain number of cycles. When the cyclic stress ratio was relatively small, the axial and torsional stress-strain hysteretic curves were linear, and almost coincided with different cycles. With the increase of the number of revolving cycles of the principal stress axis, the axial and shear stress-strain hysteresis curves became more and more nonlinear. The axial and shear stress-strain hysteresis loops of the specimens no longer coincided with the rotating circles, and the hysteresis loops gradually tilted towards the x axis. With the increase of cyclic stress ratio, the axial and shear moduli quickly attenuated at the initial stage of loading and then reached a steady value. Moreover, when the axial and shear moduli of the specimen were stable, the corresponding number of revolving cycles of the principal stress axis increased with increasing confining pressure and cyclic stress ratio.

关 键 词：原状软黏土 主应力轴旋转 软化 滞回圈 

分 类 号：TU411[建筑科学—岩土工程]