Strength and damage evolution mechanism of rock mass with holes under cyclic loading  

循环载荷作用下含孔岩体强度及损伤演化机制

作　　者：LIU Hong-tao HAN Zi-jun GUO Xiao-fei LIU Qin-yu QIAO Zhong-jin LIANG Jia-lu CHENG Wen-cong ZHANG Xi-ying ZHANG Yu-qi 刘洪涛;韩子俊;郭晓菲;刘勤裕;乔钟槿;梁嘉璐;程文聪;张熙莹;张宇淇(School of Energy and Mining Engineering,China University of Mining and Technology(Beijing),Beijing 100083,China;Research Center of Roadway Support and Surrounding Rock Control Engineering in Coal Industry,Beijing 100083,China)

机构地区：[1]School of Energy and Mining Engineering,China University of Mining and Technology(Beijing),Beijing 100083,China [2]Research Center of Roadway Support and Surrounding Rock Control Engineering in Coal Industry,Beijing 100083,China

出　　处：《Journal of Central South University》2024年第8期2717-2735,共19页中南大学学报（英文版）

基　　金：Projects(U22A20165, 52004289) supported by the National Natural Science Foundation of China;Projects(2022XJNY01, BBJ2024001) supported by the Fundamental Research Funds for the Central Universities,China。

摘　　要：The damage and failure law of rock mass with holes is of great significance to the stability control of roadways. This study investigates the mechanical properties and failure modes of porous rock masses under cyclic loading, elucidates the acoustic emission (AE) characteristics and their spatial evolution, and establishes the interrelation among AE, stress, strain, time, and cumulative damage. The results reveal that the rock mass with holes and the intact rock mass show softening and hardening characteristics after cyclic loading. The plastic strain of the rock mass with holes is smaller than that of the intact rock mass, and the stress −strain curve shows hysteresis characteristics. Under uniaxial compression, the pore-bearing rock mass shows the characteristics of higher ringing count, AE energy, b-value peak, and more cumulative ringing count in the failure stage, while it shows lower characteristics under cyclic action. At the initial stage of loading, compared with the intact rock mass, the pore-containing rock mass shows the characteristics of a low b-value. The AE positioning and cumulative damage percentage are larger, and the AE positioning is denser around the hole. The specimen with holes is mainly shear failure, and the complete specimen is mainly tensile shear failure.为研究含孔岩体的损伤演化规律、破坏特征及机理,制备了含孔试件及完整试件并进行了单轴及循环加卸载的损伤试验。基于声发射监测技术和DIC散斑技术,探究了含孔岩体在循环加卸载作用下的力学强度变化特性,掌握了含孔岩体的AE时序演化特征及AE定位点时空演化规律,建立了“声发射信号源-应力-应变-时间”的相互耦合关系,寻求声发射b值与累积损伤变量之间的关系,得到了含孔岩体的裂纹扩展特征和破坏模式。结果表明:1)含孔岩体在循环加卸载作用下强度呈现“软化”特性,而完整试件在循环加卸载作用下呈现“硬化”特性。在相同应力加载环境下,含孔岩体的塑性应变小于完整岩体,应力-应变曲线呈“滞后性”特征。2)单轴压缩下含孔岩体声发射振铃计数呈现初始波动期、静寂期、破坏活跃期及破坏突增期四个时期。在破坏阶段,含孔试件表现为AE振铃计数峰值高、AE能量峰值高、AE累计振铃计数高、b值峰值高的特性。在循环加卸载条件下,AE振铃计数及AE能量呈现“驼峰状”分布特征,在破坏阶段,含孔试件表现为AE振铃计数峰值低、AE能量峰值低、AE累计振铃计数低、b值峰值低的特性。3)不同加载条件下,在加载初期,含孔试件与完整试件相比表现为“低b值”的特性,AE空间定位声发射事件百分比及累计损伤百分比也均大于完整试件。含孔试件的AE空间定位在孔周边密集程度较高,而完整试件的声发射定位表现为无规律性。4)含孔试件在孔洞周围的应力集中下极易在孔洞的对角线附近形成宏观剪切裂纹,最终形成剪切破坏,而完整试件在拉应力作用下形成拉伸及少量斜切裂纹,最终形成拉剪破坏。

关 键 词：roadway surrounding rock control acoustic emission cyclic loading failure mode precursor of destruction 

分 类 号：TD315[矿业工程—矿井建设]