等效岩体技术在断续双节理岩石试件破裂机制细观分析中的应用

Application of equivalent rock mass technique to mesoscopic analysis of fracture mechanism of rock specimen containing two intermittent joint

采用等效岩体技术,将岩体中的岩块和节理分别用颗粒体模型和光滑节理模型描述,从细观角度开展了人工预制含两条断续节理岩石试件力学特性及破裂机制的研究。同时,结合室内试验研究成果,通过计算与试验结果的对比分析,验证了等效岩体技术在断续节理岩体力学特性研究中的适宜性和可靠性。主要研究结果如下:(1)随着断续节理产状的不同,虽可将宏观破裂划分为剪切模式、翼型张拉模式和混合模式等3种类型,但从细观角度看,颗粒间张拉型微破裂均是引起各类宏观破裂模式的主要诱因。(2)在试样达到抗压强度前,破裂声发射事件次数较少,强度均较低,主要孕育于断续节理尖端处,并沿两断续节理尖端的连线在岩桥区域累积贯通。(3)在试样达到抗压强度后,破裂声发射事件次数迅速增加,且破裂强度有所提高。(4)各类试样中,声发射事件累积数和破裂强度之间均近似满足Doseresp生长函数关系。

By using equivalent rock mass （ERM） technique, the rock block and joint are represented by bonded particle model and smooth joint model, respectively. Then, the rock specimen containing two artificial intermittent joints is constructed, and its mechanical characteristics and fracture mechanism are investigated from mesoscopic viewpoint. Meanwhile, combining with lab test result, the suitability and reliability of ERM technique used in the mechanical characteristics research of jointed rock mass are validated by comparative analysis between calculative and experimental data. The main research results are as follows： （1） With the occurrence change of intermittent joint, the macro fractures of specimen can be divided into shear mode, wing tensile mode and mixed mode. However, the tensile micro crack between particles is the main inducement that causes various macro fracture mode. （2） Before the peak compressive strength of specimen, the acoustic emission （AE） events of fracture mainly generate near the tip of intermittent joint and accumulate along the link line between the tips of the two intermittent joints in rock bridge area. In this stage, the number of AE events is less and the fracture magnitude is lower. （3） After the peak compressive strength of specimen, the number of AE events increases rapidly and the fracture magnitude enhances. （4） In different specimens, all the relationships between cumulative number of AE events and fracture magnitude approximately meet Doseresp growth function.