基于现场监测与数值模拟的浅层采空区稳定性分析

隐患采空区是目前影响露天开采矿山安全生产的主要危害源之一。随着台阶开采的不断剥离,露天开采境界内各台阶与地下空区群的隔离层厚度越来越薄,随时有可能发生采空区顶板坍塌事故。考虑到露天矿采空区地质赋存条件和围岩稳固性等特征,以弓长岭露天铁矿浅层采空区为工程背景,运用现场监测和数值模拟相结合的手段综合分析了浅层采空区的稳定性。将液体静力水准地表沉降监测系统的监测数据与FLAC数值模拟结果对比,调整蠕变参数使得数值模拟的蠕变速率与现场监测结果一致,而后据此进行未来结果的预测。最终根据地表沉降数据确定的蠕变参数取值为A=1.0×10^-12、m=1.75、n=0.35。研究表明:静力水准测点地表最大沉降位移为-9.8 mm,蠕变计算结果顶板最大垂直位移约20.4 mm,应力最大值约25 MPa,综合分析显示该采空区较稳定。上述研究提供了一种基于采空区现场监测数据的数值模拟蠕变分析方法,可为类似矿山采空区稳定性分析提供借鉴。

Stability Analysis of Shallow Goaf Based on Field Monitoring and Numerical Simulation

Hidden danger goaf is one of the main hazard sources that affect the safety production of open-pit mines atpresent.During the process of peeling off of overlying strata,the thickness between pit bottom and roofs of the cavities is be-coming thinner and thinner,which leads to the roof collapse.In this study,considering the characteristics of underground cavi-ty in open-pit mine,geotechnical conditions and stability of surrounding rock,taking the shallow goaf of Gongchangling Openpit Iron Mine as the engineering background,the stability of the shallow goaf is comprehensively analyzed by the combinationof field monitoring and numerical simulation.By comparing the monitoring data of the hydrostatic leveling system with theFLAC numerical simulation results,the creep parameters are adjusted to make the creep rate of the numerical simulation con-sistent with the field monitoring results,and then the future results are predicted based on it. Finally,according to the surfacerelative settlement data,the creep parameters are determined as A=1.0×10^-12,m=1.75,n=0.35.The study results show that themaximum ground settlement displacement of the monitoring point is-9.8 mm,the maximum vertical displacement of the roof isabout 20.4 mm and the maximum stress is about 25 MPa.The comprehensive analysis shows that the goaf is relatively stable.The above study results provides a numerical simulation creep analysis method based on the monitoring data of goaf,whichcan be used for reference for similar mine goaf stability analysis.