崩落法转充填法采矿地表移动二维离散元程序数值模拟及其规律验证

UDEC-based modelling of mining surface movement due to transforming from block caving to sublevel filling and its law verification

基于数字式全景钻孔摄像系统及现场统计对井下矿体及围岩进行了节理调查分析,利用Surpac建立了采空区三维模型并进行剖分,最终建立了二维离散元模型(UDEC),研究不同水平矿体开采时位移场的变化规律和采空区上覆岩层的冒落形式,记录并分析矿体开采过程中岩石移动角变化规律并进行了对比验证。研究结果表明:充填法开采-430^-500 m矿体时,采空区最大位移为205.6 cm,小于崩落法的215.2 cm;对比充填法和崩落法新副井沉降值和水平位移值发现,充填法地表倾斜率为0.56 mm/m,小于崩落法的1.22 mm/m,水平变形率为1.03 mm/m,小于崩落法的1.31 mm/m,对于控制新副井沉降和地表移动具有良好效果。在崩落法开采时覆岩移动存在一定间歇性和跳跃性,冒落过程中可能形成自稳平衡拱,从而形成隐伏采空区。根据实际监测与模拟结果对比,在同一水平开采时间较长时,移动角减小速率呈跳跃性非均匀变化,表现为缓慢变化-加速变化-缓慢变化-加速变化的循环过程,进一步验证了自稳平衡拱和隐伏采空区的存在。

An investigation into the joints of the ore body and rock mass at Chengchao iron mine is performed with combination of digital panoramic borehole camera system and in-situ statistics. Based on software Surpac, a 3D model for the gob is built. By subdividing the 3D model, a 2D discrete element model based on Universal Distinct Element Code is developed. The model is utilized to simulate the law of displacement fields and the rock-fall patterns of the overlying rock at different elevations when ore bodies are mined. The variations of the rock movement angle are analyzed. It is shown that： （1）When the ore bodies at the elevations between -430m and -500m are mined using back filling method; the maximum displacement for the gob is 205.6cm, which is smaller than the 215.2cm measured with the caving method. By comparing the settlement values and the horizontal displacement values of the auxiliary shaft, it is found that the incline rate of surface is 0.56mm/m for back filling method, smaller than the 1.22mm/m for the caving method; the horizontal deformantion rate is 1.03mm/m, smaller than the 1.3 lmm/m for the caving method; it is shown that the back filling method has a good effect on controlling overlying rock displacement and ground movement. （2） The movement of the overlying rock behaves in the manner of intermittence and jump when using the caving method. A self-balancing arch can be formed in the process of the overlying rock falling; hence, a number of hidden gobs may occur. Based on the comparison between the practical monitoring data and the numerical simulation, it is found that when a long period mining is carried out at a given depth, the decrease rate of movement angle exhibits a nonuniform variation mode, namely ＂slow-acceleration＂ cycle, implying the occurance of the self-balancing arches and gobs.