大倾角煤层长壁开采围岩宏观应力拱壳分析

Analysis of surrounding rock macro stress arch-shell of longwall face in steeply dipping seam mining

基于大倾角煤层开采物理相似材料模拟、数值模拟结果,分析了围岩宏观应力拱壳的力学特征,认为应力拱壳是开采扰动破坏原岩应力平衡后,围岩在自组织作用下形成的起主要承载作用的高应力形态,是在某一强度准则下强度包络线的空间展布形态,具有几何形态非对称性和应力分布非均匀性。据此,建立了应力拱壳分析模型和坐标系统,推导出宏观应力拱壳的形态方程,给出应力拱壳的稳定性判别准则,其失稳关键部位失稳主要有壳顶拉伸破坏失稳、壳肩压剪破坏失稳、壳基复合失稳3种形式,根据应力拱壳关键部位失稳过程可将应力拱壳的失稳分为"壳基-壳顶(壳肩)"失稳模式和"壳顶(壳肩)-壳基"失稳模式。

Based on the results of the physical simulation experiments and numerical simulation of steeply dipping seam mining,the mechanics characteristic of surrounding rock MSAS was analyzed,it was thought that the MSAS was formed under the action of rock self-organization after the stress distribution in mining,and was the high stress form which has the function of bearing the main load in the surrounding rock,it is the spatial distribution of intensity envelope line under the strength criterion and has the geometry shape asymmetry and the stress distribution heterogeneity.The analyzing model was constructed and the configuration equation was educed,the stability criterion of the MSAS was given.The key parts of instability mainly have three failure forms,which are the tensile instability in shell roof,the compress-shear instability in shell shoulder and the multiple instability in shell base.According to the instability process of key parts of the MSAS,instability mode of the MSAS was divided into shell base-roof（shoulder） instability mode and shell roof（shoulder）-base instability mode.