缝槽水压爆破导向裂缝扩展实验研究

针对西南地区薄煤层在使用传统深孔预裂爆破技术增加煤体透气性时，爆生裂缝无序扩展至顶底板引发顶底板失稳破断的技术难题，结合刻槽爆破裂缝导向性和水压爆破高效性，提出缝槽水压爆破技术。通过实验对比分析了耦合装药爆破、缝槽空气不耦合爆破、缝槽水压爆破形成的裂缝特征及应力演化规律。结果表明：缝槽水压爆破能大面积定向预制二维平面裂缝；在相同装药量下，缝槽水压爆破制造的煤体暴露面积是缝槽空气不耦合装药爆破的1.42倍、耦合装药爆破的11倍；其爆炸应力峰值略高于耦合装药爆破，达到割缝空气不耦合装药的1.5倍。而且，缝槽尖端方向应力变化大于其他方向，引起更大的质点振动，利于煤岩体破断，导向裂缝起裂和扩展，更有利于保护煤层顶底板。

Experimental study of propagation of directional fracture with slotting hydraulic blasting

In conventional deep-hole pre-splitting blasting to enhance the permeability of low pervious thin coal seam in Southwest China,roof collapse and floor heave usually occurs fracture propagates disorderly in blasting.To maintain the integrity of roof and floor at gateroad,a slotting-hydraulic blasting technology was proposed utilizing the fracture guidance of groove blasting and the efficiency of hydraulic blasting.Fracture initiation and stress evolution with coupling charge blasting,slotting air uncoupling charge blasting and slotting-hydraulic blasting techniques were experimentally studied.The results show that the slotting-hydraulic blasting can create two dimensional fracturesin large area along expected direction.With the same dose of explosive,exposure area is 1.42 times and 11 times of that with slotting air uncoupling charge blasting and coupling blasting,respectively.Also,the peak stress of explosion is higher than that of slotting air uncoupling charging,up to 1.5 times.It is also found that larger stress variation occurrs in the apical direction when using slot hydraulic blasting by comparing with the other two methods.This indicates that slot hydraulic blasting can lead to more violent particle vibration which is good for fracture initiation and propagation,and hence can be better for roof and floor integrity.