Developing a ground control strategy for squeezing conditions in hard rock mines

大量地下硬岩矿山暴露于大范围变形中，常被称为挤压地表条件。这对采矿业有重大的经济和安全影响，特别是在开发更深层次挖掘的地方。 大多数用于估计开挖对闭合敏感性的工具都是基于软岩中土木工程隧道的经验数据。由软弱岩石组成的岩石，即使在高度片化的情况下，也倾向于以近乎各向同性的方式表现。在叶状坚硬岩石中的开挖更容易受到各向异性行为的影响。 在采矿环境中被认为可以接受的挤压程度在采矿环境中比在隧道施工中要高得多。这为运营商提供了一些更大的灵活性。另一方面，在选择经济支持方面，地雷必须受到更高的限制。矿井挤压地面条件的特点是地面支持系统严重失灵，这往往需要进行大量的修复工作。 该项目解决了Agnico-Eagle Mines Ltd拥有的两个加拿大地下矿山LaRonde和Lapa面临的挤压岩石挑战。这两个矿山都位于魁北克西北部的Abitibi地区，面临着巨大的岩体变形。令人感兴趣的是，这两个相距11公里的矿井提供了广泛的挤压地面控制条件。

A large number of underground hard rock mines are exposed to large scale deformation often referred as squeezing ground conditions. This has major economic and safety implications for the mining industry especially where deeper excavations are developed. The majority of tools used to estimate the susceptibility of excavations to closure are based on empirical data from civil engineering tunnels in weak rock. Rock masses composed of weak rock tend to behave in a nearly isotropic fashion even when highly foliated. Excavations in foliated hard rock are more susceptible to anisotropic behaviour. The levels of what is considered acceptable squeezing in a mining environment are quite higher in a mining environment as opposed to tunnelling. This allows some more flexibility to operators. On the other hand, mines have to work with what are considerably higher constraints in the choice of economic support. Squeezing ground conditions in mines are characterized by significant failure of ground support systems that often necessitates considerable rehabilitation work. This project addresses squeezing rock challenges at two underground Canadian mines owned by Agnico-Eagle Mines Ltd: LaRonde and Lapa. Both mines are located in the Abitibi region of Northwest Quebec and are facing large rock mass deformations. Of interest is that the two mines, located 11 kilometres from each other provide a large spectrum of squeezing ground control conditions.