单轴压缩条件下平行双裂隙演化机理的颗粒流分析  

Particle flow analysis of parallel double crack evolution under uniaxial compression

作　　者：李勇[1,2] 蔡卫兵 朱维申 董振兴[1,2] 张强勇 LI Yong;CAI Weibing;ZHU Weishen;DONG Zhenxing;ZHANG Qiangyong(Geotechnical&Structural Engineering Research Center,Shandong University,Jinan 250061,China;School of Qilu Transportation,Shandong University,Jinan 250061,China;School of Civil Engineering,Shandong University,Jinan 250061,China)

机构地区：[1]山东大学岩土与结构工程研究中心,山东济南250061 [2]山东大学齐鲁交通学院,山东济南250061 [3]山东大学土建与水利学院,山东济南250061

出　　处：《中南大学学报（自然科学版）》2019年第12期3035-3045,共11页Journal of Central South University:Science and Technology

基　　金：国家自然科学基金资助项目(51879149,51779134,51579142);山东省泰山学者工程项目(2017)~~

摘　　要：基于离散元理论,研究含平行双裂隙的水泥砂浆试件在不同裂隙倾角和单轴压缩下裂纹萌生、扩展、搭接及贯通机理,并从应力场和位移场的角度分析裂纹扩展演化规律。研究结果表明:当裂隙倾角α=30°时,翼裂纹在最大应力降的作用下沿着垂直裂隙平面方向扩展至一定长度后将保持较长时间不变,直到次生裂纹大量出现后,裂隙外侧的翼裂纹才会在最大拉应力的作用下沿着最大加载方向继续扩展;在萌生初期,次生裂纹的出现会削弱了裂隙尖端的压应力集中效应,同时抑制裂隙内侧翼裂纹的扩展,最大拉应力集中在裂隙之间导致次生裂纹一般都是瞬时成片出现,且形成的裂纹的宽度远大于翼裂纹的宽度;翼裂纹主要是由颗粒之间的相对拉伸或直接拉伸产生;次生裂纹SC-1以拉裂纹的形式优先出现在裂隙尖端R1和R2之间,随着轴向应力增加,SC-1处萌生的新裂纹为拉剪复合型裂纹。The mechanism of crack initiation, propagation, and overlap in cement mortar specimens with parallel double pre-existing flaws under different fracture dip angles and uniaxial compression was investigated based on the discrete element theory. Stress field and displacement field were employed to analyze the evolution of crack propagation. The results show that when the crack inclination angle reaches 30°, the wing crack remains unchanged for a long time until the secondary crack occurs after propagating under the maximum stress drop along the vertical crack plane direction, and the wing crack on the outer side of the crack continues to expand along the maximum loading direction under the action of maximum tensile stress;At the early stage of initiation, the occurrence of secondary cracks weakens the compressive stress concentration at the crack tip and inhibits the crack propagation inside the flaw. Before the secondary crack initiation, the tensile stress is relatively large in a region between the fractures. Therefore, the secondary cracks are generally instantaneously formed, and the width of the crack formed is much larger than the width of the wing crack. The maximum tensile stress concentrated between the cracks contributes to the appearance of secondary crack with instant and much wider than that of the wing crack. Wing cracks are mainly initiated by relative or direct stretching between particles. Secondary crack SC-1 preferentially appears between crack tips R1 and R2 as tensile cracks and transforms into tensile-shear composite crack with the increasing axial stress.

关 键 词：裂纹扩展 离散元 应力场 位移场 

分 类 号：TU45[建筑科学—岩土工程]