煤层厚度变化是影响大直径钻孔卸压效果的重要因素之一。基于等效弹性模量原理建立了大直径钻孔卸压弹性力学模型，以某矿不同工作面为工程背景，研究了不同煤层厚度条件下大直径钻孔卸压煤体应力分布特征和能量释放规律，探讨了煤层厚度影响下大直径钻孔卸压释能机理。研究结果表明：当大直径钻孔卸压参数相同时，薄煤层中原岩应力、钻孔切向应力及其塑性区范围均大于厚煤层；大直径钻孔周边应力峰值随煤层厚度增加呈非线性减小趋势，当煤层厚度由1 m增加到9 m，应力峰值由23.2 MPa降低到20.2 MPa，降低12.9%；大直径钻孔卸压释能率随着煤层厚度增加呈减小趋势，当煤层厚度由1 m增加到9 m，大直径钻孔卸压释能率由68.7%降低到45.8%，即相同大直径钻孔卸压参数条件下薄煤层卸压效果更好；当大直径钻孔卸压参数相同时，钻孔切向应力随着煤层厚度增加而减小，导致煤体破碎区和塑性区范围以及存储弹性能释放量减小，即钻孔卸压释能率降低。某矿1208工作面和1203工作面煤层厚度分别为9.08、4.95 m，虽然两工作面采取了相同的大直径钻孔参数，但1208工作面巷道围岩变形破坏更为严重，对大直径卸压钻孔参数优化后，煤体平均钻屑量由2.48 kg/m下降到1.76 kg/m，表明随着煤层厚度增加，需采取减小钻孔间距、增大钻孔直径等措施来达到更好的卸压效果。

The variation of coal seam thickness is one of the important factors affecting the pressure relief of large-diameter drilling hole. We have established an elastic model of pressure relief of large-diameter drilling hole based on the principle of equivalent elastic modulus. Taking two working faces of a mine as engineering background, we have studied key issues of large-diameter drilling hole regarding coal seam thickness, including the stress distribution characteristics and energy release laws, and the pressure relief and energy release mechanism. Several phenomena of engineering significance have been revealed by our research. Firstly, when the parameters of large-diameter drilling hole are the same, the stress of primary rock, tangential stress and plastic zone range of thin coal seam are greater than those of thick coal seam. Secondly, the peak stress around the large-diameter drilling hole decreases nonlinearly with the increase of coal seam thickness. When the coal seam thickness increases from 1 m to 9 m, the peak stress drops by 12.9%, from 23.2 MPa to 20.2 MPa. Likewise, the pressure relief and energy release rate also decreases with the increase of coal seam thickness. When the coal seam thickness increases from 1 m to 9 m, the pressure relief and energy release rate of large-diameter drilling hole decreases from 68.7% to 45.8%, indicating that better pressure relief effect can be achieved in thin coal seam. Moreover, when the parameters of large-diameter drilling hole are the same, the increase of coal seam thickness causes decrease of the tangential stress and thereby results in the decrease of the range of coal fragmentation zone and plastic zone, and the amount of the released elastic energy, which reduces the pressure relief energy release rate. The coal seam thicknesses of working faces 1208 and 1203 of a certain mine are 9.08 m and 4.95 m, respectively. Although the same set of large-diameter drilling hole parameters is adopted for these two working faces, the one with thicker coal seam suffers from more serious surrounding rock deformation and failure. By optimizing the parameters of large-diameter drilling hole based on our research, the average amount of drilling cuttings decreased from 2.48 kg/m to 1.76 kg/m. Therefore, we suggest that as the coal seam thickness increases, measures such as reducing drilling spacing and increasing drilling diameter should be considered in order to guarantee the expected pressure relief effect.