单轴压缩条件下不同直径钻孔围岩稳定性研究

Study on surrounding rock stability of different diameter boreholes under uniaxial compression

为探究单轴压缩条件下含孔对煤样稳定性的影响,将煤粉按照一定配比压制成型煤,制成含有不同直径钻孔的试样,在单轴压缩机下进行单轴压缩试验。研究结果表明,型煤压制过程中的压力-位移曲线可分为3个阶段,压密阶段、等速阶段和加速阶段;单轴压缩条件下含孔试样的破坏是渐进破坏,随着压力头位移的增加,钻孔开始被压缩,孔周开始有裂纹产生与扩展,且裂纹方向近似为竖直方向,即垂直孔轴线方向;随着钻孔直径的增加,试样的强度下降越大,即钻孔直径越大,钻孔围岩的稳定性越差。

In order to explore the influence of holes on the stability of coal samples under uniaxial compression, pulverized coal was pressed into Briquetted Coal according to a certain ratio, and samples with different diameter holes were made.Uniaxial compression tests were carried out by uniaxial compressor. The results show that the pressure-displacement curve can be divided into three stages: compaction stage, constant velocity stage and acceleration stage. Under uniaxial compression, the failure of the sample with hole is progressive failure. With the increase of the displacement of the pressure head, the hole begins to be compressed, and cracks begin to appear and expand around the hole, and the crack direction is approximately vertical, that is, perpendicular to the axis of the hole;With the increase of borehole diameter, the greater the decrease of sample strength, that is, the greater the borehole diameter, the worse the stability of borehole surrounding rock.