Geotechnical risk assessment of haulage drifts during the life of a mine plan

在全球竞争激烈的矿物市场中，加拿大矿山继续面临降低成本的压力。减少采矿费用的一个办法是减少因恢复运输巷道而造成的意外生产中断。这些巷道是运输卡车和装卸车的主要道路，它们将爆破的矿石从采矿块或采场运送到最近的矿石转移设施，如矿石通道。计划外的生产中断会对采矿成本产生不利影响，并最终影响到作业的盈利能力。漂移修复包括安装额外的地面支撑，以帮助漂移恢复其稳定性和功能。因此，能够提前知道运输漂移在其使用寿命期间应在何时何地进行维护或加强支持将是有利的，这样可以及时安排和实施预防性维护计划，而不会中断生产。目前，还没有确定的准则来帮助矿山规划人员评估随采矿活动而变化（恶化）的进路稳定状况。因此，本研究项目的目标是开发新的设计工具，能够预测在巷道使用寿命期间，与预定采矿活动相关的所需巷道支护增强的位置、时间和幅度。使用这些新工具，可以消除或尽量减少对生产计划的中断，从而降低成本。新的设计工具将从研究漂移失稳的岩土风险以及它如何受到附近采矿区块开采的影响而发展。巷道岩土稳定性是通过数值（计算机）建模分析确定的，该分析考虑了岩体特性以及采矿系统和块体提取顺序的几何结构。然后将模型结果与实地测量和/或观测结果进行比较，以验证模型。该项目案例研究是淡水河谷有限公司的Garson矿。虽然这项研究的重点是Garson矿，但其研究结果将适用于加拿大和其他采矿国家的许多其他地下金属矿山。

In a globally competitive minerals market, Canadian mines continue to face the pressure to reduce costs. One approach to reducing mining costs is by the reduction of unplanned interruptions to production for the rehabilitation of haulage drifts. These drifts are the principal roadways for haulage trucks and load-haul-dump vehicles, which transport the blasted ore from the mining block or stope to the nearest ore transfer facility such as an ore pass. Unplanned interruptions to production can have adverse influence on the cost of mining and ultimately on the profitability of an operation. Drift rehabilitation involves the installation of additional ground supports to help the drift regain its stability and functionality. Thus, it would be advantageous to be able to know ahead of time when and where a haulage drift is due for maintenance or support enhancement during its service life so that a preventive maintenance program can be scheduled and implemented in a timely fashion without interruption to production. Currently, there are no established guidelines to help the mine planner assess drift stability condition as it changes (deteriorates) with mining activities. The goal of this research project is thus to develop new design tools capable of predicting the location, timing and magnitude of required drift support enhancement with respect to scheduled mining activities during the service life of the drift. With these new tools, interruption to production schedule can be eliminated or minimized thus reducing cost. The new design tools will be developed from the study of the geotechnical risk of drift instability and how it is affected by the extraction of nearby mining blocks. Drift geotechnical stability is determined from numerical (computer) modelling analyses which account for the rock mass properties as well as the geometric configuration of the mining system and block extraction sequence. Model results are then compared with measurements and /or observations from the field to validate the models. The project case study is the Garson Mine of Vale Inco Limited. While the study is focused on the Garson Mine, its findings will be applicable to many other underground metal mines in Canada and other mining countries.