基于偏应力第三不变量的窄煤柱合理宽度确定

Reasonable Width of Narrow Coal Pillar Based on the Third Invariant of Deviatoric Stress

为解决王家岭矿20103运输平巷窄煤柱合理宽度留设问题,提出了以偏应力张量第三不变量J_3为指标的研究方法。偏应力张量第三不变量表征了介质点应变行为,通过数值模拟手段进行围岩J_3来确定最优煤柱宽度问题。柱宽方案对比得出,8 m柱宽时,巷道实体煤区顶板围岩为低强度压缩应变状态,煤柱区顶板围岩为平面应变或低强度的拉伸应变状态,最终确定20103运输平巷合理的窄煤柱宽度为8 m。数值模拟和现场应用表明:剧烈综放采动影响下,8 m的窄煤柱仍存在有2~3 m的弹性核;现场未发现窄煤柱失稳现象且巷道服务状况好。

In order to tackle the problem of reasonable width of narrow coal pillar of 20103 haulage entry in Wangjialing Mine, a research method taking the third invariant of deviatoric stress J_3 as the evaluating criteria was proposed. The third invariant of deviatoric stress is used to characterize the strain behavior of the medium point and is determined by means of numerical simulation to choose the optimal width of coal pillar. The conclusion was drawn through the scheme of different pillar width comparison as follows： when the width of the 8 m column is wide, the surrounding rock of the roof above solid coal is in a state of low compressive strain, and the surrounding rock above the coal pillar is a plane strain or a low tensile strain state. Finally, the reasonable width of narrow coal pillar was determined to be 8 m in the 20103 haulage entry. The numerical simulation and field application show that the coal pillar with 8 m still has a elastic core of 2 m to 3 m under the strong influence of severe fully mechanized top coal caving mining. The instability of narrow coal pillar is not found in the field and the service condition of the haulage entry is good.