Application of seismic stress inversion to stress field mapping in deep mines

地质力学矿山设计的主要工具是数值应力分析代码。使用这些工具，可以检查备选布局和提取序列的稳定性。这些稳定性分析的最重要的输入参数是岩体强度和原地应力场的定义。岩体强度量化方法的进步是显着的，然而，很少有人注意到表征应力场。由于应力测量程序的高成本和解释结果的困难，标准做法是将应力定义为深度的线性函数，通常从区域测量数据库中编译。尽管有证据表明这一假设存在重大偏差，但仍采用了这一方法。这种简化方法很少被承认，但它严重破坏了应力分析结果的可靠性。在深、高应力和地震活跃的矿井中，这是特别成问题的，在这些矿井中，设计不确定性的后果更大，并且直接应力测量是有问题的。 本研究将利用诱发地震资料进行应力反演，以增进对深部矿井应力场特征的认识。应力反演最初是在地震学领域中发展起来的，它能够估计主应力方向和震级比。这项研究将以申请人在这一领域的工作为基础，旨在制定如何在矿山中应用该技术的程序。由于主要地质结构，矿山应力场的复杂性也将被调查，增加了我们对矿山设计目的的大规模岩体行为的理解。 这项研究的结果将被广泛应用于任何深矿井经历诱发地震，并将导致用于设计和稳定性分析的数值应力分析模型的可靠性增加。这将提高设计性能和工人安全。通过本研究，将产生两个HQP的，有益于在采矿业的人才短缺。

The primary tools used for geomechanical mine design are numerical stress analysis codes. Using these tools, the stability of alternative layout and extraction sequences can be examined. The most important input parameters for these stability analyses are rock mass strength and a definition of the in situ stress field. Advances in methods of quantifying rock mass strength have been significant; however, little attention has been paid to characterizing the stress field. Due to the high cost of stress measurement programs and the difficulties in interpreting results, standard practice is to define stresses as linear functions of depth, typically compiled from regional databases of measurements. This approach is used despite evidence of significant departures from this assumption. This simplified approach is seldom recognized as such, yet it seriously undermines the reliability of the stress analysis results. It is particularly problematic in deep, high stress, and seismically active mines, in which the consequences of design uncertainties are greater, and where direct stress measurement is problematic. This research will make use of induced seismicity data to carry out stress inversions in order to improve our knowledge of stress field characteristics in deep mines. Originally developed in the field of earthquake seismology, stress inversion enables estimates to be made of principal stress directions and magnitude ratios. The research will build on the applicant's work in this area, and is aimed at developing procedures of how to apply the technique in mines. Complexities in the stress field in mines due to major geological structures will also be investigated, adding to our understanding of large scale rock mass behaviour for mine design purposes. The results of this research will be widely applicable in any deep mine experiencing induced seismicity and will lead to increased reliability of numerical stress analysis models used for design and stability analysis. This will lead to improved design performance and worker safety. Through this research, two HQP's will be produced, benefiting the shortage of such personnel in the mining industry.