Stress-induced brittle fracturing near an excavation boundary results in a volume increase, known as bulking. Excessive bulking places added demand on the rock support, which, if not detected and addressed through preventative support maintenance (i.e., proactively added reinforcement), can cause the support to fail, leading to a safety hazard and costly production delays for underground mining operations. For caving mines, these project risks are exacerbated during cave establishment due to the large abutment stress from undercutting that redistributes and concentrates stresses near excavations critical for production. This paper reports the findings from research conducted to develop and improve geotechnical monitoring practices to support preventative support maintenance in deep mining operations. This research uses a unique geotechnical monitoring database collected for the Deep Mill Level Zone panel cave mine. The data was collected across a large footprint during the mine's ramp-up period and represents an initial step toward best practices for data collection at cave mines operating in high-stress environments. Borehole camera surveys supplemented by multi-point borehole extensometers have been used to determine the depth of stress fracturing in pillar walls as a function of the distance away from the undercut. Convergence measurements and LiDAR scanning are used to characterize the corresponding rock mass bulking. The results show that the interpretation of monitoring data can be used to identify the long-term depth of stress fracturing and bulking trends in response to undercut advances. These show that direct measures of stress-induced fracturing damage provide an early indication of excavations vulnerable to bulking and that LiDAR scanning is an effective method for capturing the onset of bulking and anticipating local areas likely to experience greater deformation demand as bulking progresses. Proactive and strategic geotechnical monitoring based on the long-term depth of stress-induced fracturing trends is proposed to assist with preventative support maintenance practices.

中文翻译：

---

监测应力引起的脆性岩体损伤，用于预防性支护维护


开挖边界附近的应力诱发脆性压裂导致体积增加，称为膨胀。过度膨胀会增加对岩石支护的要求，如果不通过预防性支护维护（即主动添加加固）来检测和解决，可能会导致支护失效，从而导致安全隐患和地下采矿作业代价高昂的生产延误。对于崩落矿，这些项目风险在洞穴形成过程中会加剧，因为底切产生的大桥台应力会重新分配和集中在对生产至关重要的开挖附近。本白皮书报告了为开发和改进岩土工程监测实践以支持深部采矿作业中的预防性支撑维护而进行的研究结果。本研究使用了为 Deep Mill Level Zone 板状洞穴矿收集的独特岩土工程监测数据库。这些数据是在矿山的爬坡期收集的，占地面积很大，代表了在高压力环境中运营的洞穴矿井中实现数据收集最佳实践的第一步。钻孔相机测量辅以多点钻孔引伸计，已被用于确定柱墙中应力破裂的深度，作为距底切距离的函数。收敛测量和 LiDAR 扫描用于表征相应的岩体膨胀。结果表明，监测数据的解释可用于确定响应底切进展的应力压裂和膨胀趋势的长期深度。 这些表明，应力引起的压裂损伤的直接测量提供了易受膨胀影响的挖掘的早期迹象，并且 LiDAR 扫描是捕捉膨胀开始并预测随着膨胀的进行而可能经历更大变形需求的局部区域的有效方法。提出了基于应力引起的压裂趋势的长期深度的主动和战略性岩土工程监测，以协助预防性支撑维护实践。