近距离煤层开采分组集中大巷稳定性数值模拟分析

针对西北地区某矿近距离煤层开采分组集中大巷稳定性问题，建立了近距离煤层开采分组集中大巷稳定性数值计算模型，分析了近距离煤层开采后顶板位移、顶板应力、围岩应力演化规律、锚杆（索）预应力场以及裂隙场演化规律。结果表明：（1）近距离煤层开采之后，大巷煤柱两侧的顶板发生断裂垮落，距离大巷煤柱越远，顶板下沉量越大；(2)随着近距离煤层开采，大巷之间保护煤柱的集中应力逐渐消失，工作面两侧大巷保护煤柱中出现10 MPa的应力集中现象，应力降低区范围大大增加，应力转移到左右工作面大巷保护煤柱中；（3）随着煤层开采，大巷围岩在地应力场与锚杆（索）预应力场的叠加场影响最小主应力的压应力逐渐增加，并在巷道周围形成了一个闭合连续的压应力带，其范围不断增大，最小主应力值逐渐减小，且下层煤的开采使上层煤的大巷锚杆（索）所受的力增加；（5）下层煤的开采使得上层煤两侧工作面大巷保护煤柱的剪切破坏带深度增加，最大破坏深度增加14 m，下层煤的大巷只在两帮出现深度为2 m的剪切破坏区，而两侧工作面的大巷保护煤柱出现10 m的剪切破坏。

Numerical simulation analysis of stability of grouped concentrated roadway in close coal seam mining

In view of the stability of grouped concentrated roadway in close coal seam mining in a mine in Northwest China, a numerical calculation model for the stability of grouped concentrated roadway in close coal seam mining is established, and the evolution laws of roof displacement, roof stress, surrounding rock stress, bolt (cable) prestress field and fracture field after close coal seam mining are analyzed. The results show that: (1) after close coal seam mining, the roof on both sides of the roadway pillar breaks and collapses. The farther away from the roadway pillar, the greater the roof subsidence; (2) With the close coal seam mining, the concentrated stress of the protective coal pillar between the main roadways gradually disappears, the stress concentration of 10MPa appears in the protective coal pillar of the main roadways on both sides of the working face, the range of the stress reduction area is greatly increased, and the stress is transferred to the protective coal pillar of the main roadways in the left and right working faces; (3) With the mining of coal seam, the compressive stress of roadway surrounding rock in the superposition field of in-situ stress field and bolt (cable) prestress field, which affects the minimum principal stress, gradually increases, and a closed and continuous compressive stress zone is formed around the roadway, its range increases, the minimum principal stress value decreases gradually, and the mining of lower coal increases the stress of roadway bolt (cable) of upper coal; (5) The mining of the lower coal increases the depth of the shear failure zone of the protective coal pillar of the main roadway on both sides of the upper coal, and the maximum failure depth increases by 14 m. The main roadway of the lower coal only has a shear failure zone with a depth of 2 m on both sides, while the protective coal pillar of the main roadway on both sides of the upper coal has a shear failure of 10 m.