Stress fields in complex rock masses

深部采矿开挖的稳定性取决于岩体强度和应力条件。估计岩体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区域的数据来估计的。尽管有文献证据表明应力会受到当地地质条件的强烈影响，但执行应力测量程序的费用和难度几乎阻碍了它们在实践中的应用。即使进行了测量，设计分析中使用的应力场也总是简化的形式。矿井中的某些地面控制问题，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。其他难以量化的设计错误无疑是通过这种简化引入的。申请人最近通过对应力测量的分析表明，某些上地壳断层系统仅处于边缘稳定状态。进一步的分析表明，在这些系统中，触发远离采矿挖掘的地震事件是自然发生的，应力场的震级和方向变化也是自然发生的。由于这些结果是新颖的，因此建议的研究重点是调查和扩展这一早期工作，以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非连续数值应力分析代码、对大型应力测量数据库的分析、矿山微地震数据、以及在构造地质学文献中可获得的有关结构的应力场的其他出版资料来进行。这项研究有望有助于我们理解复杂岩体中的应力场，如测量中的散射、矿山周围的地震活动、断层强度以及数值应力分析中指定应力场的方式。通过改进设计分析，提高矿山安全、布置效率和生产效率。通过本研究，预期培养两名博士级研究生。

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.