煤岩层静态爆破释能增透机制探讨

Research on mechanism of energy release and permeability improvement in coal strata by static blasting

针对高应力低透气煤层煤与瓦斯突出频发的问题,建立静态破岩致裂力学模型,数值模拟致裂过程,测试并分析影响致裂效果的致裂时效、膨胀压力、致裂孔布置工艺等相关参数,研究静态爆破释能防突及致裂增透机制。结果表明:配置膨胀剂、抑制剂、水分配比分别为100∶8∶30、100∶12∶30、100∶15∶30,起效时间分别为50、30、100 min的3种破碎剂;其中配比2膨胀效果最好,最大致裂压力为150.8 MPa。破碎剂膨胀稳态持续拉应力大于介质抗拉强度,实现静态爆破功能;控制孔起到裂隙扩展引导和尺寸放大作用。静态爆破降低煤体瓦斯及应力潜能积聚,增加煤体裂隙数量,达到静态爆破释能增透目的。

In order to address the problem of frequent coal and gas outburst in high-stress and lowpermeability coal seams,a static rock fracturing mechanical model was set up,and process of fracturing was numerically simulated.Then,relevant parameters of crack timeliness,inflation pressure,layout of crack hole that affect fracturing effect were tested and analyzed,and research was carried out on mechanism of energy release and outburst prevention as well as permeability improvement by static blasting.The results show that ratio of swelling agent,inhibitor and water is 100∶8∶30,100∶12∶30 and100∶15∶30,and their onset time is 50,30 and 100 min respectively.Among them ratio 2 has best expansion effect with maximum crack pressure of 150.8 MPa.Static blasting works as continuous tensile stress of cracking agent is greater than tensile strength of medium.Control holes can guide expansion of crack and enlarge its size.Moreover,static blasting can reduce accumulation of gas and stress potential and increase number of cracks in coal body,thus achieving purpose of energy release and permeability improvement through static blasting.