底抽巷条件下底板岩体变形破坏规律数值模拟研究

Numerical simulation of deformation and failure of floor rock masses under the influence of floor gas drainage roadway

为研究底抽巷道对煤层底板变形破坏规律的影响,通过建立数值模型分析有底抽巷和无底抽巷两种条件下底板岩体应力场和位移场变化特征。结果表明,底抽巷道开挖和工作面开采使得底板岩体应力场受到两次扰动,底抽巷道开挖时应力场扰动后再平衡所需时步比工作面采动时需要的平衡时步少。底抽巷开挖后在巷道松动圈外围形成高应力区,而在远离底抽巷的区域应力未被扰动;远离底抽巷区域应力大小仍与其在煤层底板中的深度呈线性关系,底板深度越大监测点的应力值越高。以底抽巷道为界,各测线监测的位移曲线在垂向上分为两组,底抽巷下方曲线呈现拱形,底抽巷上方呈现近似梯形,而且底板岩体垂向位移比无底抽巷时大。

In order to study the influence of floor drainage roadway on the deformation and failture of floor rock masses,the characteristics of floor rock masses with and without bottom stress field are analyzed by establishing a numerical model.The calculation results show that the stress field of floor rock mass is disturbed twice during mining under the condition of floor drainage roadway.The time steps required for the stress rebalance during the excavation of the bottom roadway are less than those required during the mining of the working face.When the floor gas drainage roadway is excavated,a high stress area is formed around the roadway failure circle.In the area far from the bottom extraction roadway,the stress is not disturbed and is still linearly related to the vertical depth in the coal seam floor.The stresses of the monitoring points with greater depth in the coal seam floor are higher.Taking the floor gas drainage roadway as the boundary,the shape of the lower curves under the roadway is arched,and the shape of the upper curves above the roadway is approximately trapezoidal.The vertical displacement of floor rock mass is larger than without the floor gas drainage roadway.