不同开采条件下岩石的变形破坏特征及对比分析

基于3种典型的煤层开采方式(无煤柱开采、放顶煤开采和保护层开采)，借助MTS- 815电液伺服岩石实验系统对潞安李村煤矿灰岩进行了同时恒定降围压、变速率加轴压的三轴卸荷试验，由此研究了不同开采卸荷条件下的应力路径对围岩的力学行为影响。实验获得了不同围压不同加载速率条件下灰岩的全应力-应变曲线及宏观破坏模式，认为灰岩的破坏模式与达到峰值时围压的大小有很大关系，而轴向加载应力路径影响较小；放顶煤开采条件下围岩的变形较保护层开采和无煤柱开采要大，特别是塑性变形较后两者也大。另外围岩的脆性和延性特征的转变与轴向加载速率有很大关系，即与煤层开采方式有关，并且围压越大，塑性特征越明显。

Deformation failure mechanism and analysis of rock under different mining condition

Based on three typical mining models(non pillar mining，top coal caving and protected coal seam mining)，a series of triaxial tests which keeping confining pressure at the same unloading rate and axial pressure in different loading rates were carried out on the limestone samples through MTS 815 electrohydraulic servo Rock Test System.Based on experimental results，the relationship between stress path and surrounding rock under different mining conditions was investigated in detail.The complete stress strain curves and macro damaged characteristics were studied and compared.The experimental results indicate that the failure mode is mainly related to the confining pressure near peak strength rather than the axial loading rate under unloading condition.The top coal caving can lead to more bigger deformation and plastic deformation than non pillar mining and protected coal seam mining.The axial loading rate transform the rock property between brittle and ductile，when the confining pressure is bigger，the conversion of brittle ductile property will be more obviously.