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作 者:蒲诚 刘奉银[1] 陈蕴生[1] PU Cheng;LIU Fengyin;CHEN Yunshen(Institute of Geotechnical Engineering,Xi'an University of Technology,Xi'an 710048,Shaanxi,China)
机构地区:[1]西安理工大学土木建筑工程学院岩土工程研究所,陕西西安710048
出 处:《实验力学》2020年第6期1121-1128,共8页Journal of Experimental Mechanics
基 金:国家自然科学基金(51679198,41372304);西北旱区生态水利国家重点实验室项目(QNZX-2019-07)资助。
摘 要:岩体峰后强度的研究被广泛应用在深部煤炭开采和隧道安全施工中。依托大南湖二号边坡工程,采用水泥砂浆材料来模拟该区域泥岩,通过埋置薄铜片后抽出的形式制作非贯通裂隙,利用三轴压缩试验获得全应力-应变曲线,研究围压及裂隙倾角对试件残余强度、试件峰后塑性、黏聚力和内摩擦角的影响。结果表明:裂隙对试件残余强度的影响主要是在高围压条件下,低围压下裂隙对试件残余强度的影响较小;试件峰后塑性特征受围压及裂隙倾角的共同影响,其中围压对试件峰后塑性特性起决定性作用,裂隙倾角仅在一定范围内影响试件峰后塑性;峰后黏聚力的大小与破坏方式及破坏程度有关,裂纹长度越大、试件破坏后形态越不完整,峰后黏聚力越小;峰后内摩擦角正切值的大小与裂纹表面的粗糙程度及裂纹数量有关,裂纹表面越粗糙、裂纹数量越多,峰后内摩擦角正切值越大;75°倾角裂隙试件在中高围压下会产生较为明显的剪切破坏进而导致峰后段应力的突然跌落。The study of post-peak residual strength of rocks has great importance for tunnel safe construction and deep coal mining engineering.In this work,the rock-like materials are used to simulate rock mass,the embedded sheet metals are used to simulate non-penetrating crack in rock mass.The complete stress-strain curves are obtained by the triaxial compression test.The influences of confining pressure and crack inclination on the residual strength,the post-peak plasticity,the cohesive force and the internal friction angle are analyzed.The results indicate that the crack has little influence on the residual strength under low confining pressures,while has high influence under moderate and high confining pressures.The post-peak plastic characteristics of specimen are affected by both confining pressure and crack angle,among which the confining pressure plays a decisive role in the post-peak plastic characteristics of specimen,while the crack angle only affects the post-peak plasticity within a certain range.Value of the residual cohesive force is related to the failure mode and failure degree.The longer the crack length is and the more incomplete the specimen is after failure,the smaller the residual cohesive force is;and the value of tangent of internal friction angle is related to the roughness on the crack surface and the number of cracks.The rougher the crack surface is and the more number of cracks is,the higher the tangent of internal friction angle is.Finally,under moderate and high confining pressures,the specimen with a 75°crack angle has obvious shear failure,which will lead to the sudden drop of the stress in the post-peak section.
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