厚煤层综放工作面沿空掘巷坚硬顶板水力压裂弱化技术研究

Study on hydraulic fracturing weakening technology for hard roof of gob-side entry driving in fully mechanized top coal caving face in thick coal seam

为解决山西三元煤业沿空4306回风巷围岩变形破坏严重的问题,通过煤柱受力分析得出巷道围岩变形破坏的关键因素,提出了具体的水力压裂实施方案,并且在相邻的4302工作面回风巷实施了坚硬顶板水力压裂弱化技术。结果表明:注水压力最大值约为30 MPa,最小值约为22 MPa,每个钻孔每个压裂位置的平均注水时间均约为18 min,每个压裂位置的注水量约为1 m^(3);水力压裂影响范围在7.0~10.0 m;水力压裂后,部分钻孔中致裂段可以观察到明显的宏观轴向及径向裂缝。现场工程的成功应用表明坚硬顶板水力压裂弱化技术能够明显改善厚煤层综放工作面沿空掘巷巷道的应力环境,增强围岩稳定程度。

In order to solve the serious problem of surrounding rock deformation and damage of 4306 air return roadway along the goaf in Shanxi Sanyuan Coal Industry Co.,Ltd.,the key factors of surrounding rock deformation and damage were obtained from the stress analysis on the coal pillar,the specific implementation scheme of hydraulic fracturing was put forward,and the hydraulic fracturing weakening technology of hard roof was implemented in the air return roadway of adjacent 4302 working face.The results showed that the maximum water injection pressure was about 30 MPa and the minimum was about 22 MPa,the average water injection time at each fracturing position of each borehole was about 18 minutes,and the water injection volume at each fracturing position was about 1 m^(3) and the range affected by hydraulic fracturing was 7-10 m.After the hydraulic fracturing,obvious macroscopic axial and radial fractures could be observed in the fracturing section of some boreholes.The successful application of field engineering showed that the hydraulic fracturing weakening technology for hard roof could significantly improve the stress environment of gob-side entry driving in fully mechanized top coal caving face in thick coal seam and enhance the stability of surrounding rock.