Abstract: During the mining process of the fully mechanized top coal caving face along the goaf,due to the large and severe damage area of the upper rock layer,the mining pressure is prominent. In addition,frequent mining activities cause serious damage to the surrounding rock of the narrow coal pillar roadway. Based on this,a comprehensive control technique combining far-field weakening and near-field strengthening,abbreviated as joint prevention and control technology is proposed (referred to as the " combined prevention and control technique" ). This combined prevention and control technique includes two sub-techniques. One is the stability control technique of the goaf based on far-field weakening,which weakens the lateral roof of the goaf through hydraulic cutting,reduces the activation degree of overlying rock,blocks stress transmission,and improves the stress environment of the roadway, thereby reducing stress concentration. The second is the far-field weakening and near-field strengthening reinforcement technique for goaf roadways,which enhances the mechanical properties of the fractured rock mass around the tunnel through anchor support and grouting reinforcement,improves its bearing capacity and deformation resistance, and strengthens the stability of the surrounding rock. The experimental results show that after using the proposed combined prevention and control technique,the maximum approach displacement reduction of the roadway roof and floor is 77. 66% and 61. 96%,respectively,and the maximum displacement reduction of the solid coal support and small coal pillar support is 46. 9% and 72. 75%,respectively. When only using the near-field strengthening technique,the axial force of the anchor rod under near-field strengthening is 118 kN,and the anchor cable is 246 kN. After adopting the combined prevention and control technique,the axial force of the anchor rod is reduced to 93 kN and the anchor cable is reduced to 175 kN,with a decrease of 21. 2% and 28. 9%,respectively. The proposed technique can effectively reduce the support burden and minimize the range of rock damage. The study results are of great significance for ensuring the safety of the fully mechanized mining process in thick coal seams. 

Key words: ultra-thick coal seam,comprehensive mining surface,goaf-side roadway,rock stability,far-field weakening, near-field enhancement