芦子沟矿厚煤层沿空掘巷窄煤柱宽度优化及应用

Width optimization and application of narrow coal pillar in gob-side entry driven in thick coal seam in Luzigou Mine

护巷煤柱宽度是沿空掘巷技术成功与否的关键。以芦子沟矿8103工作面沿空掘巷工程为背景,采用理论分析、数值模拟和现场试验等方法,研究沿空掘巷内外应力场传递演化规律,确定沿空掘巷内应力场分布范围,对比分析不同宽度护巷煤柱下巷道围岩的形变特征,得到最优护巷煤柱宽度为8m。结果表明:内外应力场呈“双驼峰”状分布,内应力场范围为12.2~13.8m,巷道布置在内应力场范围内不会引起支承压力的明显变化,能够保持巷道相对稳定;煤柱宽度由3m增加至35m时,煤柱内垂直应力增长率出现先增大后减小的趋势;煤柱宽度为3~8m时,煤柱内垂直应力分布近似为“单驼峰”,煤柱宽度为10~35m时,煤柱内垂直应力分布近似为“双驼峰”。随着煤柱宽度的增大,煤柱内部弹性核区不断增加,煤柱塑性区形状由“贯穿”状向“H”形过渡,直至发展为“X”形;煤柱内部破坏方式由“拉、剪复合破坏”向“剪切破坏为主”发展,最终破坏形式为“全剪破坏”。现场试验表明:宽度为8m的护巷煤柱可以有效地控制巷道围岩变形量,能够维持巷道整体稳定;与原护巷煤柱相比,煤炭损失率降低了77.15%,提高了煤炭资源采出率。

The width of roadway protection coal-pillar is the key to the success of the gob-side entry driving technology.With the gob-side entry driving project of 8103 working face in Luzigou Mine as the background,theoretical analysis,numerical simulation,field test and other methods were used to study the transmission and evolution law of internal and external stress field in gob-side entry driving.The distribution range of internal stress field in gob-side entry driving is determined.The deformation characteristics of the roadway surrounding rock under different widths of roadway protection coal-pillar are compared and analyzed,and the optimal width of roadway protection coal-pillar width is 8 m.The results show that the internal and external stress fields are double hump-shaped,the internal stress field range is 12.2-13.8 m,and the roadway layout will not cause obvious changes in the support pressure within the range of the internal stress field,and the roadway can be kept relatively stable.When the width of the coal pillars are increased from 3 m to 35 m,the vertical stress growth rate in the coal pillars shows a trend of"first increasing and then decreasing";When the width of the coal pillars is 3 m to 8 m,the vertical stress distribution in the coal pillars is approximately"single hump",and when the width of the coal pillars is 10-35 m,the vertical stress distribution in the coal pillars is approximately"double hump".With the increase of the width of the coal pillars,the elastic core area inside the coal pillars continues to increase,and the shape of the plastic area of the coal pillars transitions from"through"to"H"shape until it develops into an"X"shape;The internal destruction mode of the coal pillars develops from"tensile and shear mixed destruction"to"shear damage-based",and the final destruction form is"full shear destruction".Field tests show that the coal pillars with a width of 8 m can effectively control the deformation of the surrounding rock of the roadway and maintain the overall stability of the roadway;compared with the original coal pillars,the coal loss rate of pillars with the width of 8 m is reduced by 77.15%,which improves the coal resource extraction rate.