中等压缩性粉质黏土不排水剪切强度试验研究  

Experimental Study on Undrained Shear Strength of Medium-compressibility Silty Clay

作　　者：张崇磊[1,2] 朱秦 李丞 刘琪 蒋关鲁[4] Zhang Chonglei;Zhu Qin;Li Cheng;Liu Qi;Jiang Guanlu(Key Laboratory of Mountain Surface Processes and Ecological Regulation,Institute of Mountain Hazards and Environment,Chinese Academy of Sciences,Chengdu 610041,P.R.China;CAS Center for Excellence in Tibetan Plateau Earth Sciences,Chinese Academy of Sciences(CAS),Beijing 100101,P.R.China;University of the Chinese Academy of Science,Beijing 100049,P.R.China;School of Civil Engineering,Southwest Jiaotong University,Chengdu 610031,P.R.China)

机构地区：[1]中国科学院、水利部成都山地灾害与环境研究所山地灾害与地表过程重点实验室,成都610041 [2]中国科学院青藏高原地球科学卓越创新中心,北京100101 [3]中国科学院大学,北京100049 [4]西南交通大学土木工程学院,成都610031

出　　处：《地下空间与工程学报》2019年第6期1620-1629,共10页Chinese Journal of Underground Space and Engineering

基　　金：国家自然科学基金国际(地区)合作与交流项目(41761144077);国家自然科学基金(51808542)

摘　　要：为获得原状中等压缩性粉质黏土的剪切刚度和抗剪强度,开展了直剪固结快剪和固结不排水三轴剪切(CU)对比试验,分析了偏应力随整体、局部轴向应变的发展,研究了整体、局部变形测量获得抗剪强度的差异,探讨了刚度衰减特征,提出了固结快剪和CU试验抗剪强度之间的关系。结果表明:变形测量方式对粘聚力c’影响显著,与整体相比,局部粘聚力c’提高2.9~11.1 kPa,局部内摩擦角φ’低0.4°~1.7°。剪切刚度Esec随轴向应变ε1增加呈反"S"形衰减。应变ε1<0.005%时,局部测量刚度Esec高于整体,其衰减幅度显著,但随轴向应变增加,二者刚度差值缩小。直剪试验与CU试验抗剪强度差值随着竖向应力的增加而增大,CU试验抗剪强度明显高于直剪,建立了抗剪强度参数的修正关系。To obtain the small strain stiffness and shear strength of medium-compressibility silty clay,consolidated-quick direct shear test and consolidated-undrained triaxial shear test(CU) were conducted. The development of deviatoric stress with overall and local axial strain was analyzed,and the differences in shear strength indexes between overall and local deformation measurements were investigated. The attenuation characteristics of secant stiffness at different strain intervals were explored. Finally,the correction relationship of shear strength between consolidated-quick shear test and CU test was put forward. Experimental results demonstrate that the method for deformation measurement influences cohesive strength significantly. Compared with overall values,local cohesive value increases by 2. 9 ~ 11. 1 k Pa,and local internal friction angle reduces by 0. 4° ~ 1. 7°. Shear stiffness Esec periodically attenuates with the increase of axial strain,presenting reverse-S shape. At small strain(< 0. 005%),local measured stiffness Esecis higher than overall stiffness,showing significant attenuation trends. However,with the increase of axial strain,the difference between local and overall stiffness reduces. The difference in shear strength between direct shear test and CU test increases with the increase of vertical stress. Shear strength in CU test is evidently higher than that of direct shear test. The correction relationship of shear strength indexes is firstly established.

关 键 词：粉质黏土 抗剪强度 轴向应变 三轴剪切试验 中等压缩性 

分 类 号：TU43[建筑科学—岩土工程]