基于矿物晶体模型的非均质裂隙花岗岩双轴压缩微裂纹演化特征  

Microcracks evolution of heterogeneous fissured granite under biaxial compression based on grain-based numerical modeling

作　　者：严旭锋 张振宇[1,2] 郝胜鹏 窦浩然 YAN Xufeng;ZHANG Zhenyu;HAO Shengpeng;DOU Haoran(State Key Laboratory of Coal Mine Disaster Dynamics and Control,Chongqing University,Chongqing 400044,China;School of Resources and Safety,Chongqing University,Chongqing 400044,China)

机构地区：[1]重庆大学煤矿灾害动力学与控制全国重点实验室,重庆400044 [2]重庆大学资源与安全学院,重庆400044

出　　处：《采矿与岩层控制工程学报》2024年第4期98-110,共13页Journal of Mining and Strata Control Engineering

基　　金：重庆市杰出青年科学基金资助项目(CSTB2023NSCQ-JQX0075)。

摘　　要：为深入研究非均质矿物晶体微观结构影响下裂隙花岗岩的力学特性和损伤演化规律,结合花岗岩力学试验结果,开发了考虑矿物晶体结构影响的离散元数值模型,通过开展不同围压下裂隙花岗岩压缩试验,建立了围压和裂隙倾角双重因素影响下花岗岩应力峰值经验模型,从微观尺度上阐明了花岗岩微裂纹破裂机理。研究结果表明:(1)随裂隙倾角的增加,花岗岩抗压强度呈先降低后升高的趋势,在无围压条件下,裂隙倾角θ=31.8°时花岗岩的抗压强度最低。(2)应力加载过程中,花岗岩微裂纹演化呈空间局部化,沿晶张拉裂纹随机分布在试样内部,穿晶张拉裂纹则主要聚集在裂纹扩展阶段的断面附近,并伴随着宏观断裂。(3)随着围压的增大,总微裂纹数量逐渐增加,穿晶张拉裂纹在总微裂纹中的占比明显上升,围压为0,10,20和30 MPa时,穿晶张拉裂纹分别占总数的36.1%,45.0%,48.3%和51.4%。(4)非均质裂隙花岗岩强度特征受矿物基质空间分布的影响,正长石会阻止微裂纹的扩展和聚合。与单一剪切断面花岗岩相比,非均质性影响下“V”形宏观裂纹的花岗岩应力峰值更高。In order to study the mechanical properties and damage evolution of fissured rocks under the influence of microstructure caused by inhomogeneous mineral crystals,a grain-based model considering the influence of mineral crystal structure was developed by combining the results of mechanical tests on granite.An empirical model of peak stress under the influence of the dual factors of circumferential pressure and fissure inclination was established by carrying out the compression numerical modeling of fissured granite with different peripheral pressures,and the rupture mechanism of microcracks was elucidated on a microscopic scale.The results show that with the increase of fracture inclination angle,the compressive strength of granite exhibits a first decrease and then increase trend,with the lowest strength observed at an inclination angle of 31.8°under no confining pressure.During the stress loading process,the microcrack evolution in granite is spatially localized.Intergranular tensile cracks are randomly distributed within the granite sample,whereas transgranular tensile cracks primarily congregate near the fracture surfaces during the crack propagation stage,accompanied by macroscopic failure.With the increase of the peripheral pressure,the total number of mineral cracks gradually increased,and the proportion of the crystal⁃piercing tensile cracks in the total cracks increased significantly,and tensile transgranular cracks accounted for 36.1%,45.0%,48.3%and 51.4%of the total number of cracks at the peripheral pressures of 0,10,20 and 30 MPa,respectively.The strength characteristics of non⁃homogeneous fractured granite are affected by the spatial distribution of mineral matrix,and orthoclase prevents the expansion and aggregation of microcracks.Specimens with V⁃shaped macroscopic cracks under the influence of non⁃homogeneity have the higher peak stresses when compared to granite with a single shear cross section.

关 键 词：非均质性 裂隙花岗岩 GBM模型 双轴压缩 破裂模式 

分 类 号：TD324[矿业工程—矿井建设]