瓦斯压力对砂岩渐进破坏特征的影响研究

Study on effect of gas pressure on progressive damage characteristics of sandstones

借助多场多相耦合下多孔介质压裂—渗流试验系统,基于不同瓦斯压力下的常规三轴加载试验,通过分析砂岩的力学特性和渐进破坏规律,研究砂岩在不同瓦斯压力下开采的渐进破坏演化过程。研究结果表明,随着瓦斯压力增加,砂岩的裂纹闭合应力会呈现增加趋势,而损伤应力以及峰值应力呈现减少趋势;瓦斯压力对砂岩的峰值强度起到了弱化作用,且随着瓦斯压力增加,弱化程度随之增加;不同瓦斯压力下的砂岩在受载破坏过程中都呈现相同的变化趋势,总体分为裂纹闭合阶段、弹性阶段、微小裂纹扩展阶段、宏观裂纹扩展阶段;随着瓦斯压力增加,砂岩的裂纹闭合阶段在峰前的占比呈现增加趋势,而弹性阶段和微小裂纹扩展阶段在峰前的占比呈现减少趋势。该研究对地下深部巷道的开挖和稳定性有重要指导意义。

The progressive damage evolution process of sandstone mining under different gas pressure is studied by analyzing the mechanical properties and progressive damage law of rock samples with the help of fracturing and seepage experimental system for multi-physical field and multiphase coupling of porous media,based on conventional triaxial loading test under different gas pressure.The results show that the crack closure stress of sandstone will show an increasing trend with the increase of gas pressure,while the damage stress as well as the peak stress will show a decreasing trend.The gas pressure plays a weakening effect on the peak strength of sandstone,and the degree of weakening increases with the increase of gas pressure.The sandstones under different gas pressures all show the same trend of change during the damage by loading,which are generally divided into crack closure stage,elastic stage,microcrack expansion stage,and macrocrack expansion stage.With the increase of gas pressure,the percentage of crack closure stage in sandstone in front of the peak shows an increasing trend,while the percentage of elastic stage and micro crack extension stage in front of the peak shows a decreasing trend.This study has important guiding significance for the excavation and stability of deep underground tunnels.