坚硬顶板定向水力压裂切顶机理及应用

Mechanism and application of directional hydraulic fracturing roof cutting in hard roof

为促进顶板及时垮落,保证安全生产,在恒晋煤业E9105工作面开展了坚硬顶板定向水力压裂切顶技术的研究。根据断裂力学理论,建立了地应力和水压力共同作用下的裂纹扩展力学模型,推导得出了Ⅰ型、Ⅱ型复合裂纹扩展的强度因子计算公式。基于最大周向拉应变准则,分析了裂纹的起裂条件和起裂规律。结果表明,当原始裂纹方向平行或垂直于σ_(1)的方向时,裂纹为自相似扩展。随着水压的增大,开裂角逐渐减小,裂纹主要为Ⅰ型扩展。结合E9105工作面的地质情况,计算了水压的大小,并与实际相差较小。该技术的应用明显减小了来压步距,降低了支架工作阻力,可为类似条件下的顶板控制提供参考。

In order to promote roof caving in time and ensure safe production,the research on directional hydraulic fracturing roof cutting technology for hard roof was carried out in E9105 working face of Hengjin Coal Industry.According to the theory of fracture mechanics,the mechanical model of crack propagation under the combined action of ground stress and water pressure was established,and the formula for calculating the strength factors of typeⅠand typeⅡcomposite crack propagation were derived.Based on the maximum circumferential tensile strain criterion,the crack initiation conditions and crack initiation rules were analyzed.The results show that when the original crack direction is parallel or perpendicular to the direction ofσ_(1),the crack is self-similar manner.With the increase of water pressure,the cracking angle decreases gradually,and the crack is mainly typeⅠexpansion.Combined with the geological conditions of the E9105 working face,the size of the water pressure was calculated,and the difference with the actual was small.The application of this technology significantly reduces the weighting interval and the working resistance of the support,which can provide reference for roof control under similar conditions.