含卸压孔煤岩蠕变特性数值模拟研究

Numerical simulation study on creep characteristics ofcoal rock with pressure relief holes

随着煤炭开采深度的增加,煤岩体赋存条件变得更加复杂,冲击地压事故频发,严重影响了煤炭的安全高效开采。大直径钻孔卸压是治理冲击地压的有效方法之一,为了研究含卸压孔煤岩的蠕变特性,基于FLAC3D数值模拟软件,采用Burgers蠕变本构模型开展了煤岩蠕变数值模拟研究,对比分析了单轴压缩条件下完整试样与含卸压孔试样在不同应力水平下的蠕变特性,结果表明:蠕变曲线全面反映了数值模型的瞬时弹性变形、减速蠕变和等速蠕变的演化阶段;卸压孔为煤岩体提供了变形补偿空间,减少了巷道的变形量;在合理的卸压孔尺寸范围内,卸压孔直径越大,其可为煤岩提供的变形空间越大,越有利于减小冲击地压。工程应用结果显示,卸压后的巷道变形量为同时期未卸压巷道变形量的70%左右。研究成果可为煤矿巷道的长期稳定和冲击地压解危提供参考。

As the depth of coal mining was increasing,the occurrence of coal rock mass was found more complicated,the frequent rock burst accidents has badly affected the safe and efficient coal mining operation and the pressure relief of boreholes of large diameter was one of the effective approaches to deal with rock burst.In order to understand the creep characteristics of coal rock with pressure relief holes,a numerical simulation study on coal rock creep was carried out based on FLAC 3D numerical simulation software and Burgers creep constitutive model.The creep characteristics of intact samples and samples with pressure relief holes under uniaxial compression at different stress levels were com-paratively analyzed.The results show that the creep curve fully reflects such evolution stages as instantaneous elastic deformation,decelerating creep and constant rate creep using the numerical model.The pressure relief holes provided deformation compensation space for coal rock mass and lessen the deformation of roadway.Within the reasonable range of pressure relief holes in size,the larger the pressure relief holes,the more deformation space it can provide for coal rock,and the more facilitated to reduction of rock burst.The practical application of the study results show that the roadway deformation after pressure relief was about 70%of that without pressure relief in the same period.The research results can be provided as reference for maintaining stable coal mine roadway for a long time and relieving rock burst.