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

用于地质力学矿山设计的主要工具是数值应力分析程序。使用这些工具，可以检查备选布局和提取序列的稳定性。这些稳定性分析最重要的输入参数是岩体强度和原位应力场的定义。量化岩体强度的方法取得了重大进展；然而，对应力场的表征却很少关注。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。尽管有证据表明与这一假设存在重大偏差，但仍使用了这种方法。这种简化的方法很少被认可，但它严重破坏了应力分析结果的可靠性。在深部、高应力和地震活跃的矿井中，设计不确定性的后果更大，直接应力测量也有问题，这尤其成问题。

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.