Stress fields in complex rock masses

深部采矿开挖的稳定性既取决于岩体强度又取决于应力条件。估计岩石强度的方法相对发达，但相比之下，应力条件通常是根据整个地区的数据来估计的。尽管有文件证明应力会受到当地地质条件的强烈影响，但实施应力测量计划的费用和难度几乎排除了它们在实践中的使用。即使进行了测量，设计分析中使用的应力场也总是具有简化形式。某些矿山的地面控制问题，包括远离采矿挖掘的地震事件，不能用这种简单的方法来解释。使用这种简化无疑会引入其他较难量化的设计误差。申请人最近通过对应力测量的分析表明，某些地壳上部断层系统只是边缘稳定的。进一步的分析表明，在这些系统中，在远离采矿挖掘的地方触发地震事件是一种自然现象，应力场的大小和方向的变化也是如此。由于这些结果是新的，拟议的研究侧重于调查和扩展这一早期工作，以便表征矿山典型复杂地质环境中的应力场。这项工作将使用连续和不连续数值应力分析程序、应力测量大型数据库的分析、矿山的微地震数据，以及与构造地质学文献中提供的与构造有关的应力场的额外出版信息来进行。这项研究将有助于我们理解复杂岩体中的应力场，如测量中的散布、矿山周围的地震活动、断层强度以及数值应力分析中应力场的确定方法。通过改进的设计分析，将提高矿井的安全性、布置效率和生产率。通过这项研究，预计将培养两名博士生。

Stability of mining excavations at depth depends on both rock mass strength and stress conditions. Methods of estimating rock mass strength are relatively well developed, but in contrast, stress conditions are generally estimated from data assembled for entire regions. Although there is documented evidence that stresses can be strongly influenced by local geological conditions, the expense and difficulty of carrying out stress measurement programs has all but precluded their use in practice. Even when measurements are made, stress fields used in design analysis invariably have simplified forms. Certain ground control problems in mines, including seismic events located far from mining excavations, cannot be explained using this simple approach. Other less quantifiable design errors are undoubtedly introduced using this simplification.The applicant has recently shown through analysis of stress measurements that certain upper crustal fault systems are only marginally stable. Further analysis has shown that triggering of seismic events remote from mining excavations is a natural occurrence in these systems, as is the variation in magnitude and direction of the stress field. Since these results are novel, the proposed research focuses on investigating and extending this early work in order to characterize stress fields in complex geological settings typical of mines. The work will be carried out using continuum and discontinuum numerical stress analysis codes, analysis of large databases of stress measurements, microseismic data from mines, plus additional published information on stress fields in relation to structures that is available in the structural geology literature. This research is expected to contribute towards our understanding of stress fields in complex rock masses such as scatter in measurements, seismic activity around mines, fault strength, and the way in which stress fields in numerical stress analyses are specified. Through improved design analysis, mine safety,  layout efficiency and productivity will be increased.Through this research, training of two Ph.D. level graduate students is anticipated.