加载速率对大尺寸试样破裂特性的影响规律

结合当前我国矿井高强度快速推采的现状，系统分析了双轴加载速率对大尺寸岩体破裂的影响规律。以山东能源济宁矿区深部岩体所处的复杂环境为背景，确定了与深部岩体力学特性相似的混合砂浆材料的最优配比。采用自主研发的岩石应力-渗流耦合真三轴试验系统和美国生产的PCI-2声发射系统，分析了双轴加载下加载速率对大尺寸试样破裂的影响规律，揭示了加载过程中单裂隙和双裂隙试样的破裂和声发射行为特征。研究表明:当加载速率为1.5 kN/s时，单裂隙试样在剪切作用下易起裂形成反翼裂隙；试样双裂隙的岩桥倾角越大，越有利于试样的加速破坏，产生的声发射事件数较少，表现出岩体破裂的突变性。 

Influence of loading rate on the fracture characteristics of large-size specimen

According to the high mining speed of modern mines in China, the fracture characteristics of rock mass under different uniaxial loading rate was systematically analyzed. Based on the geological condition of deep rock mass in Jining area, the optimum mortar composed of 425 Portland cement, sand with particle size less than 2 mm, gypsum, water and high efficient water reducer was used, which had the mechanical properties similar to real rock mass was ascertained. Applying the triaxial rock test system of coupled stress-seepage and PCI-2 real-time monitoring system of AE, the fracture process of specimens of large size under biaxial loading was studied, the evolution law and AE behavior feature of specimens with prefabricated single and double cracks under different loading rate were obtained. The results show that the specimen with single crack is easy to develop anti-wing crack due to shear stress when loading rate is 1.5 kN/s; the bigger of rock bridge angle between cracks, the easier to accelerate fracture of specimen and the less AE events appear, which shows the fracture mutation of rock mass.