复杂地质条件下矿区初始地应力场反演分析

Back analysis of initial geostress field of mining areas under complex geological conditions

初始地应力场是地下工程设计和稳定性分析的重要依据。前常铁矿矿区地质构造复杂、巷道围岩破坏严重,掌握矿区地应力场的分布规律对了解巷道破坏、进行支护设计具有重要意义。采用三维有限差分数值计算软件(Flac^(3D)),建立了考虑矿区主要断层、岩层等的三维数值模型,进行矿区地应力场的模拟,分析了矿区整体、地质构造处和-480 m中段地应力场特征。结果表明:矿区地应力以自重应力为主,分层现象明显,应力值随埋深增加而逐渐增大,地质构造和岩性交接带对地应力的影响十分显著,出现不同程度的应力集中现象;F_(1)断层形成的构造应力对-480 m中段主运输巷道影响相对较大;-480 m中段主运输巷道侧压力系数为0.46~0.58,最大水平主应力与巷道走向的夹角为2.60°~47.75°,对维持其稳定性不利。为减小地应力场对巷道稳定性的影响,建议矿区地下巷道的布置遵循巷道走向与最大水平主应力方向平行的原则。

Initial geostress field is very important reference for engineering design and stability analysis of underground engineering.The geological structures are complex,and the roadway surrounding rocks are damaged seriously in Qianchang Iron Mine mining area.So,it is important to master the distribution rules of the geostress field in the mining area for better understanding of roadway failure and supporting design.3D numerical model taking into account the main fault and strata in the mining area is established by using the three-dimensional finite difference numerical calculation software(Flac^(3D)),and simulates the geostress field in the mining area,analyzes the geostress characteristics in the whole mining area,geotectonic locations and the-480 m level.The results show that the geostress in the mining area is dominated by gravity stress and the stratification phenomenon of geostress is obvious and the value gradually increases with depth,the geostress is affected so seriously at the junction of geological structures and lithology that stress concentration phenomena of different degrees occur;the tectonic stress of F_(1) fault has relatively great influence on-480 m level main haulage way;the lateral pressure coefficient of-480 m level main haulage way is 0.46-0.58,the angle between the maximum horizontal principal stress and the direction of the roadway is 2.60°-47.75°,which is unfavorable to maintain stability.In order to reduce the influence of geostress field on the stability of roadway,it is suggested that the layout of underground roadway should follow the principle that the direction of roadway is parallel to the direction of maximum horizontal principal stress.