郭家湾煤矿5-1煤层工作面在回采过程中顶板垮落不及时，来压步距大，威胁工作面的人员设备安全。为此，在51212工作面开展了切顶卸压技术的研究。力学参数测试表明，粉砂岩的单轴抗压强度为56.84 MPa，RQD值为93%，属于比较坚固稳定岩层。该类岩层垮落滞后，在采空区形成悬顶效应，其垮落步距的大小受顶板单轴抗拉强度、岩层的厚度等影响。水力压裂通过间接降低工作面宽度，达到减少来压步距的目的。结合工作面地质条件，确定了切顶方案并进行了现场应用。结果表明，采用水力压裂切顶后，51212工作面初采顶板垮落及时，与未切顶工作面相比，初次来压步距和周期来压步距相比分别减少36.1%、29.5%，取得了理想的效果。

 The roof caving of 5-1 coal seam working face in Guojiawan Coal Mine was not timely in the process of mining, and the weighting step was large, which threatened the safety of personnel and equipment in the working face. Therefore, the research on roof cutting and pressure relief technology was carried out in NO.51212 Face. The test of mechanical parameters showed that the uniaxial compressive strength of siltstone was 56.84 MPa, and the RQD value was 93 %, which belonged to a relatively strong and stable rock layer. The caving of this kind of rock stratum lagged behind, and the hanging roof effect was formed in the goaf. The size of the caving step was affected by the uniaxial tensile strength of the roof and the thickness of the rock stratum. Hydraulic fracturing achieved the purpose of reducing the pressure step by indirectly reducing the width of the working face. Combined with the geological conditions of the working face, the roof cutting scheme was determined and applied on site. The results showed that after hydraulic fracturing and roof cutting, the initial mining roof of NO.51212 Face collapsed in time. Compared with the non-cutting working face, the initial weighting step and the periodic weighting step were reduced by 36.1 % and 29.5 % respectively, and the ideal effect was achieved.