预留煤柱形状对煤矿工作面稳定性的影响研究

Study on the influence of reserved coal pillar shape on the stability of coal mine working face

煤矿开采过程中常需预留煤柱支撑上部岩体,预留煤柱的径高比和大小不尽相同,对工作面的稳定性影响较大。通过对煤体及煤岩组合体进行不同径高比下的单轴压缩数值模拟试验,分析煤体和煤岩组合体的力学性质及破裂过程,研究不同径高比预留煤柱对工作面稳定性的影响。结果表明:(1)随着径高比逐渐增大,煤体和煤岩组合体峰值强度同步增大,煤体先由脆性向延性转变,随后又由延性向脆性转变,煤岩组合体也由脆性破坏向延性破坏转变,延性逐渐降低;(2)随着径高比逐渐增大,煤体及煤岩组合体主要以劈裂破坏为主,且引起煤体裂纹破坏的扩展方向动态变化,煤岩组合体随煤体的劈裂破坏而破坏;(3)随着径高比逐渐增大,煤岩组合体与煤体的峰值强度差值也变大,煤体峰值轴向应变随着径高比的增大无明显变化,煤岩组合体峰值轴向应变呈一定程度增大,且当D/L=0.8时,峰值轴向应变较高。

In the process of coal mining,it is often necessary to reserve coal pillars as load-bearing columns to support the gravity of the upper rock mass.Due to the different width-height ratios of the reserved coal pillars on site,it has a great impact on the stability of the coal mine working face.Through uniaxial compression numeri‐cal tests conducted under different diametral-height ratios of coal rocks and their assemblages,the mechani‐cal properties and fracture process of coal rock and its mass under different diameter-height ratios were ana‐lyzed to investigate the influence of reserved coal pillars and their mass on the stability of the working face.The results showed that:(1)As the ratio of diameter to height increased gradually,the peak strength of coal rock and its mass increased synchronously.The coal rock changed from brittle to ductile,and then from duc‐tile to brittle,and the mass rock changed from brittle failure to ductile failure,with the ductility of the mass de‐creasing gradually with the continuous increase of the ratio of diameter to height.(2)With the gradual in‐crease of the diameter to height ratio,the coal rock and its mass were mainly subjected to split failure,and the expansion direction of the crack failure is constantly changing dynamically,and the basic coal rock of the mass being broken by splitting failure.(3)The difference in peak strength between mass mass and coal rock was larger with the gradual increase of diameter to height ratio.The peak axial strain of coal rock showed no significant change with the increase of diameter to height ratio.The general trend of peak axial strain of mass mass increased with the increase of diameter to height ratio to a certain extent,and the peak axial strain of mass mass was higher when D/L=0.8.