大断面巷道见顶见底掘进支护最优方案数值模拟研究

Numerical simulation study on optimal scheme of supporting and bottom driving in large section roadway

为分析大断面巷道见顶见底掘进支护的最优方案,采用数值模拟的方法开展研究。根据新源煤矿地质条件,建立数值模拟。通过对掘支后的不同间距、排距、角度等因素影响下的应力云图进行分析得到,在垂直方向上应力区域不断增加,但在宽度方向上有效应力区域不随之增加;在锚索中上部的应力逐渐减小,支护效果逐渐减小;两锚索之间中部的围岩压应力逐渐变小,支护作用变小;当预应力不变时锚索长度与支护效果成反比。根据实际生产中的具体情况,选择锚索的长度为5.3 m;模拟得到锚索角度与支护效果成反比,在近水平煤层巷道中,考虑锚索预应力的条件下,顶板锚索最好的布置方式为垂直布置,施工过程中锚索角度应尽量保持在10°以内;当锚杆间距小到一定程度时,锚杆的有效应力去将连成一体,零应力区域消失。而且锚杆密度足够小时,再增加锚杆数量起到的支护作用变化不大。综合考虑锚杆和锚索应力场叠加,并对现场施工和生产环境综合分析,最终选择锚杆间距为1.0 m,锚索间距选择2.0 m;根据数值模拟的结论,设计了巷道合理的支护方案和支护参数。

In order to analyze the optimal scheme of the top-and-bottom digging support of a large-section roadway,a numerical simulation method was used for research.Based on the geological conditions of Xinyuan Coal Mine,a numerical simulation was established.By analyzing the stress cloud diagrams under the influence of different spacing,row spacing,angle and other factors after the excavation,the stress area increases continuously in the vertical direction,but the effective stress area did not increase in the width direction;The stress gradually decreased,and the supporting effect gradually decreased;the surrounding rock compressive stress in the middle between the two anchor cables gradually decreased,and the supporting effect became smaller;when the pre-stress was constant,the length of the anchor cable was inversely proportional to the supporting effect.According to the specific conditions in actual production,the length of the anchor cable was selected to be 5.3 m;the angle of the anchor cable was simulated to be inversely proportional to the support effect.In the near-level coal seam,considering the prestress of the anchor cable,the roof anchor cable was the best.The angle of the anchor cable should be kept within 10°as much as possible during construction.When the distance between the anchor rods was small to a certain extent,the effective stress of the anchor rods would be integrated into one,and the zero-stress area would disappear.Moreover,the density of the anchor rod was small enough,and the support effect of increasing the number of anchor rods did not change much.Considering the superposition of the stress field of the anchor rod and the anchor cable,and comprehensively analyzing the construction and production environment of the site,the anchor bolt spacing was selected to be 1.0 m,and the anchor cable spacing was selected to be 2.0 m.Based on the conclusion of the numerical simulation,a reasonable support for the roadway was designed of the scheme and support parameters.