露天矿山转地下开采隔离层安全厚度及采动稳定性研究

Investigation on safety thickness of isolation layer and mining stability for mine from open-pit to underground mining

为了合理确定隔离层厚度和保障矿山安全生产,以某铜矿露天转地下联合开采为工程背景,采用理论计算和FLAC3D数值模拟相结合的方法,探讨地下矿体回采过程对隔离层位移场、应力场的影响。研究结果表明:隔离层安全厚度的理论值为11.43~31.18 m,现有厚度为57 m,满足规范要求;地下矿体-100 m及-150 m中段回采引起的隔离层沉降主要发生在第一分层,最大值为21.7 mm;最大主应力表现为竖向压应力,其变化范围为7~10 MPa,最小主应力只出现在第一分层,为拉应力,其值最大为0.18 MPa,远小于岩体抗压、抗拉强度,隔离层整体上未发生破坏性的变形。研究结果可为类似条件矿山露天转地下联合开采预留隔离层设计及稳定性分析提供参考。

In order to reasonably determine the thickness of the isolation layer and ensure the safety production,taking the combined mining from open-pit to underground in a copper mine as the engineering background,the combined method of theoretical calculation and FLAC3 D numerical simulation was used to study the influence of underground mining process on the displacement field,stress field and plastic zone of the isolation layer.The results showed that the theoretical value of the safety thickness of isolation layer was 11.43~31.18 m,and the current thickness was 57 m,which could meet the safety requirement of the specification.The settlement of isolation layer caused by the mining at the levels of underground-100 m and-150 m middle section mainly occurred in the first slice,and the maximum value was 21.7 mm.The maximum principal stress presented as the vertical compressive stress,which varied from 7 to 10 MPa.The minimum principal stress only appeared in the first slice and presented as the tensile stress,and the maximum value was 0.15 MPa,which was far less than the compressive and tensile strength of rock mass.Overall,no destructive deformation occurred in the isolation layer.The research results provide reference for the design and stability analysis of the reserved isolation layer for the combined mining from open-pit to underground in the similar mines.