端帮采场支撑煤柱峰值应力及塑性区宽度确定方法

Determination method of peak stress and plastic zone width ofsupporting coal pillar in end-slope mining field

为了保证边坡安全的同时回收更多的露天矿边帮压煤,首先采用离散元仿真软件模拟再现端帮煤开采全过程,监测并分析采硐群支撑煤柱受力和变形特征;然后构建不同采硐深度下的3种支撑煤柱竖向荷载分布模型,建立端帮采场采硐与围岩力学分析模型。结果表明:沿采硐延深方向,支撑煤柱竖向受力与变形呈现出典型的分段特征;自采硐口向内,随着采硐深度的增加,竖向应力首先呈线性增大,达到峰值后,在采硐末端前、后约3倍采硐宽度范围内骤然减小至坡体初始应力并保持不变;基于采硐施工前、后采场上覆岩体竖向应力恒定原理,得到不同采硐深度下的煤柱峰值应力确定方法;基于极限平衡理论和Mohr-Coulomb强度准则,推导出峰值应力作用下的煤柱单侧塑性区最大宽度估算公式。

In order to realize the maximum recovery of end-slope coal under the premise of ensuring the safety of the slope,the whole process of end-slope coal mining was simulated by using discrete element simulation software.The stress and deformation characteristics of supporting coal pillars were monitored and analyzed,three vertical load distribution models of supporting coal pillars under different roadway depths were constructed,and the mechanical analysis model of roadway-surrounding rock in an end-slope mining field was established.The results show that the vertical force and deformation of the supporting coal pillar show typical segmentation characteristics along the direction of the roadway.From the roadway mouth to the inside,with the increase of roadway depth,the vertical stress increases linearly at first.After reaching the peak,it suddenly decreases to the initial stress of the slope and remains unchanged in the range of about 3 times the width of the roadway before and after the end of the roadway.Based on the principle of constant vertical stress of overlying rock mass before and after roadway construction,the determination method of peak stress of coal pillar under different mining depths is obtained.Based on the limit equilibrium theory and Mohr-Coulomb strength criterion,a formula for estimating the maximum width of the plastic zone on one side of the coal pillar under peak stress is derived.