含水量对粘土与结构物接触界面单剪特性影响规律试验研究
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摘要
采用升级改造后的DSJ-2型直剪仪,在不同法向应力水平下,开展了不同含水量的粘性土与不同介质性质的地下结构物接触界面的单剪试验,探索揭示粘土含水量变化对接触界面的剪切力学行为影响规律。研究结果表明:随着粘土含水量的增大,基底刚度较大时,剪应力-剪切位移曲线应变硬化现象愈来愈明显,反之,愈来愈不明显。剪切法向应力处于较低水平时,粘土的含水量对刚度较大的混凝土基底界面剪应力峰值强度影响更明显,反之,刚度相对较小的木材基底更明显。不同性质基底同粘土单剪时,随其含水量的不断提高,接触界面的内摩擦角均是不断降低,但其降低幅度不尽相同,结构物的刚度对接触界面内摩擦角起控制作用。随着粘土含水量的增大,接触界面的粘聚力总体变化规律为先增大,增大到某一峰值点后降低,界面的粘聚力由土体与结构物共同控制,且同结构物的刚度大小和界面自身特性均密切相关。
In order to explore the influence of water content of clay on the shear mechanical behavior of contact Interface with the help of modified DSJ-2 electric quadruple strain direct shear experimental system,single shear experiment for clay soil with different water content and for contact interface between underground structure and different medium properties were carried out under condition of different normal stress levels.Results show that with the increase of water content of clay,the strain hardening phenomenon of shear stress-shear displacement curve is more and more obvious when base stiffness is larger,and vice versa.Under lower normal stress level,the shear stress peak strength of contact interface with larger stiffness is more sensitive to water content of clay,however,under higher normal stress level,the contact interface of timbering with smaller stiffness is more sensitive.The friction angles of contact interface all reduce with the increase of water content of clay,but the reduction amplitude varies and the sensitivity is different.Cohesion force of contact interface increases first and then decreases with the increase of water content of clay,which has a peak point.Cohesion force of contact interface is closely related with both clay and structure,it is not only related to the structural stiffness,but also to the structure interface characteristics.
In order to explore the influence of water content of clay on the shear mechanical behavior of contact Interface with the help of modified DSJ-2 electric quadruple strain direct shear experimental system,single shear experiment for clay soil with different water content and for contact interface between underground structure and different medium properties were carried out under condition of different normal stress levels.Results show that with the increase of water content of clay,the strain hardening phenomenon of shear stress-shear displacement curve is more and more obvious when base stiffness is larger,and vice versa.Under lower normal stress level,the shear stress peak strength of contact interface with larger stiffness is more sensitive to water content of clay,however,under higher normal stress level,the contact interface of timbering with smaller stiffness is more sensitive.The friction angles of contact interface all reduce with the increase of water content of clay,but the reduction amplitude varies and the sensitivity is different.Cohesion force of contact interface increases first and then decreases with the increase of water content of clay,which has a peak point.Cohesion force of contact interface is closely related with both clay and structure,it is not only related to the structural stiffness,but also to the structure interface characteristics.
引文
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[2]凌华,殷宗泽.非饱和土强度随含水量的变化[J].岩石力学与工程学报,2007,26(7):1499-1503(LING Hua,YIN Zongze.Variation of unsaturated soil strength with water contents[J].Chinese Journal of Rock Mechanics and Engineering,2007,26(7):1499-1503(in Chinese))
[3]陈东霞,龚晓南,马亢.厦门地区非饱和残积土的强度随含水量变化规律[J].岩石力学与工程学报,2015,34(s1):3484-3490(CHEN Dongxia,GONG Xiaonan,MA Kang.Variation of the shear strength of Xiamen unsaturated residual soils with water content[J].Chinese Journal of Rock Mechanics and Engineering,2015,34(s1):3484-3490(in Chinese))
[4]郭彪,陈贺,李亚军.变附加应力条件下考虑桩体二维井阻作用的复合地基固结解析理论研究[J].岩石力学与工程学报,2017,36(3):754-761(GUO Biao,CHEN He,LI Yajun.Analytical study on consolidation of composite ground considering two-dimensional well resistance under time and depth dependent stresses[J].Chinese Journal of Rock Mechanics and Engineering,2017,36(3):754-761(in Chinese))
[5]李飒,李忠刚,周扬锐,等.循环荷载作用下饱和粘土中的有效应力原理的实验研究[J].实验力学,2010,25(3):279-285(LI Sa,LI Zhonggang,ZHOU Yangrui,et al.Experimental study of the effective stress principle in saturated clay under cyclic loading[J].Journal of Experimental Mechanics,2010,25(3):279-285(in Chinese))
[6]张嘎,张建民.粗粒土与结构接触面单调力学特性的试验研究[J].岩土工程学报,2004,26(1):21-25(ZHANG Ga,ZHANG Jianmin.Experimental study of monotonic behavior of interface between soil and structure[J].Chinese Journal of Geotechnical Engineering,2004,26(1):21-25(in Chinese))
[7]徐泽友,卢廷浩,丁明武.高塑性黏土与混凝土接触面剪切特性[J].河海大学学报:自然科学版,2009,37(1):71-74(XU Zeyou,LU Tinghao,DING Mingwu.Shear properties at interface between highly plastic clay and concrete[J].Journal of Hohai University:Natural Sciences,2009,37(1):71-74(in Chinese))
[8]高俊合,于海学,赵维炳.土与混凝土接触面特性的大型单剪试验研究及数值模拟[J].土木工程学报,2000,33(4):42-46(GAO Junhe,YU Haixue,ZHAO Weibing.Characteristics study of interface between soil and concrete by using large size single shear apparatus and numerical analysis[J].China Civil Engineering Journal,2000,33(4):42-46(in Chinese))
[9]朱俊高,Shakir R R,杨有莲,等.土-混凝土接触面特性环剪单剪试验比较研究[J].岩土力学,2011,32(3):692-696(ZHU Jungao,Shakir R R,YANG Youlian,et al.Comparison of behaviors of soil-concrete interface from ring-shear and simple shear tests[J].Rock and Soil Mechanics,2011,32(3):692-696(in Chinese))
[10]王伟,卢廷浩,宰金珉,等.土与混凝土接触面反向剪切单剪试验[J].岩土力学,2009,30(5):1303-1306(WANG Wei,LU Tinghao,ZAI Jinmin,et al.Negative shear test on soil-concrete interface using simple shear apparatus[J].Rock and Soil Mechanics,2009,30(5):1303-1306(in Chinese))
[11]陈希哲.土力学地基基础[M].北京:清华大学出版社,2000(CHEN Xizhe.Soil mechanics and geotechnical engineering[M].Beijing:Tsinghua University Press,2000(in Chinese))
[12]杨大方.土与结构界面模型单剪与直剪试验对比研究[D].河南理工大学,2009(YANG Dafang.Comparison research between simple shear tests and direct shear tests on interfacial model between soil and structure[D].Institutes of Technology of Henan,2009(in Chinese))
[13]中华人民共和国国家标准编写组.GB/T50123-1999土工试验方法标准[S].北京:中国计划出版社,1999(The National Standards Compilation Group of Peoples Republic of China.GB/T50123-1999Standard for soil test method[S].Beijing:China Planning Press,1999(in Chinese))