坚硬顶板磨砂射流轴向切顶防冲技术研究

Bursting preventation of hard roof by axialslit cutting and fracturing with abrasive jet

为了探索煤矿坚硬顶板处理的新方法,引入坚硬顶板磨砂射流轴向切顶技术,通过开展工业性试验,确定了割缝、压裂的关键技术参数,并进行了防冲工程实践,采用水压仪、钻孔窥视和观测孔出水观测、微震监测、支架压力监测和煤体应力监测等方法进行了效果检验。研究结果表明,割缝参数为:割缝深度200m,割缝长度300m,割缝压力40~50MPa;压裂参数为:压裂压力50~55MPa,压裂时间20~30min;割缝、压裂后有效促使了顶板岩层裂隙的产生和扩展,破坏了顶板的完整性,压裂半径10~20m。相较于传统爆破切顶防冲技术,采用磨砂射流轴向切顶和爆破组合处理后,微震事件集中区域由超前工作面80m转移至130m,微震能量释放以小能量事件为主;周期来压步距明显降低,采动应力影响范围和应力集中系数明显减小,围岩活动强度和动载效应明显减弱,取得了良好的防冲效果。

To explore a new method of hard roof treatment in coal mine,the axial cutting technology of hard roof with abrasive jet is introduced,and the key technical parameters of slit cutting and fracturing are determined by carrying out industrial tests,and the anti-impact engineering practice is carried out.Its performance is evaluated by means of water pressure meter,borehole observation and observation hole outflow observation,microseismic monitoring,support pressure monitoring and stress monitoring in coal seam.The results show that the reasonable slit cutting parameters are as follows:slit depth 200 m,slit length 300 m,slit pressure 40-50 MPa;The fracturing parameters are as follows:fracturing pressure 50-55 MPa,fracturing time 20-30 min;After slit cutting and fracturing,it effectively promotes the generation and propogation of cracks in roof strata,and undermines the integrity of the roof.The fracturing radius is 10-20 m.Compared with the traditional roof cutting technology of top blasting,the microseismic event concentration area is transferred from 80 m to 130 m in advance of working face,and the microseismic energy release is mainly small energy events after the combined treatment of abrasive jet axial top-cutting and blasting.The pressure step of the period is obviously reduced,the influence range of mining stress and stress concentration coefficient are obviously reduced,the activity strength and dynamic load effect of surrounding rock are obviously weakened,achieving good bursting preventation effect.