基于数值分析的露转地境界顶柱合理厚度值预测研究

Research on the Prediction of the Reasonable Thickness of the Boundary Pillar in Underground Mining Transferring from Open-pit Based on Numerical Analysis

针对某铜铁矿露天矿转地下开采过程中面临的境界顶柱合理厚度值与地下开采稳定性间的复杂关系,采用FLAC3D对同一跨度采空区进行10组不同厚度值下的模拟,并结合安全系数等传统的评价指标进行空区关键点的位移、应力、塑性区等情况统计,最终与4种传统顶板预测法对比分析。研究表明:顶板位移值与厚度值呈非线性负相关,与安全系数呈非线性正相关;当境界顶柱为21 m时,位移处于变化速率的"突变点",可作为合理厚度预测值;数值模拟法预测的21 m合理厚度值远比传统方法预测值误差小,相对误差仅为2.2%。模拟预测值具有较高参考价值,同时能保证较高的安全性和资源利用率。

Reasonable thickness of the boundary pillar is a key factor for the stability of under-ground mining transferring from open - pit. Using the simulation software FLAC30 , ten goaf models with different thicknesses under the same span were established to analyze the displacements, stres-ses and plastic zones of key monitoring points combined with the traditional evaluation index such as safety factor. Finally, the results were compared with four traditional roof prediction methods. The research indicated that the displacement value of roof was negatively correlated with the thickness, and the safety factor was nonlinear. According to the mutation point of displacement curve, the rea-sonable thickness of the boundary pillar was 21 m. Relative error of numerical simulation method was only 2. 2% , which was far less than those of the traditional methods. The predictive value of the model is of high reference value, and could guarantee the high security and resource utilization.