Evaluation of fault-slip potential in underground mines

在加拿大的地下硬岩矿山中，发现断层和剪切带等地质构造并不少见。在断层位于活跃矿区附近的情况下，矿石的开采可能会导致断层突然移动，从而在矿井中产生强烈的地震波。这一事件被称为断层滑动，其产生的地震波可能会对附近的矿场造成严重破坏，甚至造成人员伤亡。该项目的目标是开发先进的计算机模型，以充分描述在地下矿山中观察到的断层滑动现象。在这些模型的基础上，将推导出简单的公式，以帮助工程师估计维持即将到来的断层滑动所需的额外岩石加固，并以最有效的方式规划采场开采计划。为了做到这一点，选择了一个案例研究矿山。这是淡水河谷-萨德伯里公司的加森矿。该矿已有100多年的生产历史，目前正在1.5公里深的地方开采。加尔逊矿以地质构造复杂著称，近年来随着开采深度的增加至1.5公里，该矿微震活动增强，并记录到多次冲击地压。这项研究的第一步是收集该矿发现的所有岩石材料的相关数据。将特别注意解释过去与采矿活动有关的微地震记录。将开发一些三维先进的计算机模型来模拟矿山采场和周围的地质结构，包括断层。在将模型结果与地震记录进行比较后，将确定并保留最好的计算机模型。在选定的计算机模型的帮助下，将产生广泛的数值结果并进行统计分析，以推导出描述断层性质与地震参数之间关系的简单方程。这个过程被称为回归分析。回归分析得到的关系可作为预测断层滑动发生的实用矿山安全工具，并有助于估计断层滑动引起的地震波的破坏程度。

It is not uncommon that geological structures such as faults and shear zones are found in underground hard rock mines in Canada. In the case that faults are located close to active mining areas, the extraction of ore could cause the fault to suddenly move thus creating strong seismic waves across the mine. This event is known as fault-slip and the seismic waves generated by it could result in severe damage to nearby mine openings and even personnel injuries. The goal of this project is to develop advanced computer models that adequately describe the fault-slip phenomenon observed in underground mines. Based on these models, simple equations will be derived to help the engineer estimate the additional rock reinforcement required to sustain imminent fault-slip, and to plan the stope extraction schedule in the most efficient way. In order to do that, a case study mine is selected. This is the Garson mine of Vale - Sudbury Operations. The mine has been in production for more than 100 years and mining is currently being done at a depth of 1.5 km. Garson mine is known for its complex geological structures and with the increase of mining depth to 1.5 km in recent years, the microseismic activities in the mine have increased and a number of rockbursts have been recorded. The first step in this research is to gather all the relevant data of the rock materials found in the mine. Particular attention will be paid to the interpretation of past microseismic records with respect to mining activities. A number of 3-dimensional advanced computer models will be developed to simulate the mine stopes and surrounding geological structures including faults. After comparison of model results with seismic records, the best computer model will be identified and retained. With the help of the selected computer model, a wide range of numerical results will be generated and analysed statistically to derive simple equations describing the relation between the fault properties and seismic parameters. This process is known as regression analysis. The relationships obtained from the regression analysis can serve as practical mine safety tools to predict the occurrence of fault-slip and help estimate the damage by seismic waves arising from fault-slip.