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

在全球竞争激烈的矿产市场中，加拿大矿山继续面临降低成本的压力。降低采矿成本的一种方法是减少因修复运输平巷而造成的生产意外中断。这些平巷是运输卡车和装载-运输-倾卸车辆的主要道路，它们将爆破的矿石从采矿块或采场运输到最近的矿石转运设施，例如矿石溜井。生产的意外中断可能对采矿成本产生不利影响，并最终影响经营的盈利能力。平巷修复包括安装额外的地面支撑，以帮助平巷恢复其稳定性和功能。因此，有利的是能够提前知道运输平巷在其使用寿命期间何时和何处应进行维护或支撑增强，使得预防性维护程序可以及时地安排和实施而不中断生产。目前，没有既定的指导方针，以帮助矿山规划师评估平巷稳定性条件，因为它的变化（恶化）与采矿活动。因此，本研究项目的目标是开发新的设计工具，能够预测在平巷使用寿命期间，相对于计划的采矿活动，需要加强平巷支护的位置、时间和规模。有了这些新工具，生产计划的中断可以消除或最小化，从而降低成本。新的设计工具将从研究巷道不稳定的岩土工程风险以及它如何受到附近采矿块开采的影响中开发出来。巷道岩土工程稳定性通过数值（计算机）建模分析确定，该分析考虑了岩体特性以及采矿系统的几何配置和块体开采顺序。然后将模型结果与来自现场的测量和/或观察进行比较，以验证模型。该项目的案例研究是淡水河谷国际有限公司的加尔森矿。虽然这项研究的重点是加尔森矿，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。

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.