饱和含水条件下煤矿膨胀岩钻孔缩径弹塑性分析

Elastic-plastic Analysis of Borehole Shrinkage of Coal Mine Expansive Rock Under Saturated Water

通过建立煤矿膨胀岩钻孔受力平衡方程,考虑膨胀和软化特性,进行弹塑性力学分析,确定了饱和含水条件下煤矿膨胀岩钻孔围岩的塑性区半径和径向位移。以重庆某矿8#煤层底板岩巷为研究背景进行实例计算,分别研究了饱和含水条件下地应力场和孔内水压力对钻孔缩径变形的影响规律。结果表明:随着钻孔围岩地应力p的增大,塑性区半径和孔壁径向位移均在不断增加,都呈明显的非线性关系,水的存在加剧了地应力对煤矿膨胀岩钻孔缩径变形的影响;随孔内水压的增加,钻孔围岩塑性区半径和孔壁径向位移呈减小的趋势,适当提高孔内水压可以有效地控制钻孔缩径。

By establishing the equilibrium equation of swelling rock boreholes in coal mines,considering the expansion and softening properties,the elastic-plastic mechanics analysis was carried out,and the plastic zone radius and radial displacement of the surrounding rock of the swelling rock in coal mines were determined under the coupling of humidity and stress field.According to an example based on the research background of the floor rock roadway in the 8#coal seam of Songzao Coal Mine in Chongqing,the calculation results were carried out,and the influence of water content,ground stress and water pressure inside the hole on boreholes shrinkage was studied.The results show that with the increase of the ground stress p,the radius of the plastic zone and radial displacement of boreholes walls are increasing,showing a significant nonlinear relationship.The presence of water exacerbates the influence of ground stress on boreholes shrinkage in coal mines.The larger the water pressure in the boreholes,the smaller the radius of plastic zone and radial displacement of boreholes walls,and properly increasing the water pressure in the boreholes can effectively control the boreholes shrinkage.