基于COMSOL的穿层钻孔周围应力带及漏风原理研究

COMSOL-based Study of Stress Zones and Air Leakage Principle around Cross-seam Boreholes

为了有效防止煤与瓦斯突出灾害事故发生,以雨汪煤矿一井3#煤层穿层钻孔为研究对象,理论分析了钻孔周围应力场分布规律和渗透率变化情况,通过COMSOL数值模拟软件研究了钻孔周围应力带、水平应力和垂直应力的分布情况,以及钻孔周围的变形特征,提出钻孔周围漏风圈结构模型。经模拟发现,钻孔开挖后周围应力为“左右受压,上下受拉”的“蝶状”分布;周围塑性区呈圆形分布,94 mm钻孔附近距孔壁0~2.8 mm为裂隙区,2.8~39.0 mm为塑性区,39~93 mm为弹性区,93 mm以上为地应力场区;钻孔周围最大的漏气通道是I裂隙区和II塑性区。通过现场应用可知,使用根据数值模拟结果调配的水泥浆,并采用“两堵两注”的封孔方式,可有效封堵钻孔周围裂隙,有较好的封孔效果。

To effectively prevent coal and gas outburst disasters,taking the No.3 coal seam cross-seam drilling in Well One in Yuwang Coal Mine as the research object,the theoretical analysis was conducted on the stress field distribution and permeability variation around the boreholes.By COMSOL numerical simulation software,we studied the distribution of the stress zones,horizontal stress,and vertical stress and the deformation characteristics around boreholes.Based on these,we proposed a structural model for the air leakage circle around boreholes.The simulation revealed a“butterfly”stress distribution around boreholes with“compression on the left and right,tension on the top and bottom”and a circular distribution of the plastic zones.Near the 94 mm borehole,the area within 0~2.8 mm from the borehole-wall was identified as the fracture zone,within 2.8~39.0 mm as the plastic zone,within 39~93 mm as the elastic zone,and beyond 93 mm as the in-situ stress field zone.The largest air leakage channels around the boreholes were the fracture zone I and the plastic zone II.Field application showed that the cement slurry prepared according to the numerical simulation and the sealing method of“two-plug and two-injection”could effectively seal the cracks around the boreholes,achieving a better sealing effect.