Long reinforcement strategies for underground mines

对矿产资源需求的增加导致开采更深的矿石储量和使用更高生产率的采矿方法。在这些条件下，主要的工程挑战之一是在困难的地面条件下保持地下开挖的稳定性。岩石不稳定是地下矿山中造成伤害的最大原因，并可能导致采矿作业暂停和关闭。当岩石中的破坏区域延伸到墙的深处时，传统的岩石锚杆是不够的，并且需要使用更长的加固单元，例如电缆锚杆来支撑挖掘。 锚索是由多股钢丝组成的高承载力长柔性地基钢筋束。它们的性能主要是通过实验室测试确定的，很难将其结果外推到现场条件。锚索锚固策略基于经验方法，该方法涉及理想条件，仅包括几种可用的锚杆类型，并不适用于所有开挖壁。仪表电缆螺栓提供电缆性能的有用信息，但没有完全集成在支撑设计中。数值模拟可以补充仪器数据，为制定锚索策略提供合理和可靠的方法。这要求我们对锚索的行为有很好的理解，并且数值模型可以在不同条件下再现各种锚索类型的明确行为。 拟议的研究计划旨在通过现场拉力试验和现场试验，在入口和非入口地下开挖，提高我们对不同类型的锚索性能的理解。现场监测，包括先进的3D激光扫描方法，引伸计和仪表螺栓，将允许在现场不同条件下表征不同电缆螺栓类型和配置的性能。将使用先进的3D数值建模方法来明确捕获不同电缆的性能以及入口和非入口开挖的不同阶段的3D破坏区。 该计划将建立在我以前的工作上使用仪器和先进的显式建模的岩石破坏机制和行为的钢筋。这将增加我们对电缆现场机械性能的了解。研究结果将为锚索设计提供改进的指导方针和工具，并最终提高地下作业的安全性和成本效益。加拿大采矿业是加拿大经济财富的主要贡献者，并且严重缺乏能够从事地面控制工作的高素质人员。该计划将大大有助于培养研究生，他们将获得理论知识和现场经验，应用基本原理解决矿山真实的问题。

The increased need for mineral resources has lead to the exploitation of deeper ore reserves and the use of mining methods with higher production rates. In these conditions, one of the main engineering challenges is to maintain the stability of underground excavations under difficult ground conditions. Rock instability is the biggest cause of injuries in underground mines and can result in the suspension and closure of mining operations. When the zone of failure in the rock extends deep inside the walls, traditional rock bolts are not adequate and the use of longer reinforcement units, such as cable bolts is necessary to support the excavation. Cable bolts are high capacity long flexible ground reinforcement tendons comprised of multi wire strand. Their performance has been mostly determined from laboratory tests and is difficult to extrapolate their results to field conditions. Cable bolting strategies are based on empirical methods that refer to ideal conditions, include only a few of the available bolt types and are not applicable to all the excavation walls. Instrumented cable bolts provide useful information of cable performance but are not fully integrated in the support design. Numerical modelling can complement instrumentation data to provide a rational and robust approach for developing cable bolt strategies. This requires that we have a good understanding of the behaviour of cable bolts and that numerical models can reproduce the explicit behaviour of various cable bolt types under different conditions. The proposed research program aims on improving our understanding on the behaviour of different cable bolt types through in-situ pull tests and field trials in entry and non-entry underground excavations. Field monitoring, including advanced 3D laser scanning methods, extensometers and instrumented bolts will allow to characterize the performance of different cable bolt types and configurations under different conditions in the field. Sophisticated 3D numerical modelling methods will be used to capture explicitly the performance of the different cables and the 3D zone of failure in different stages of entry and non-entry excavations. The program will build on my previous work on the use of instrumentation and advanced explicit modelling of the rock failure mechanism and the behaviour of reinforcement. It will allow to increase our knowledge on the in-situ mechanical behaviour of the cables. The results will provide improved guidelines and tools for cable bolt design and ultimately improve the safety and cost effectiveness of underground operations. The Canadian mining industry is a main contributor to the economic wealth of Canada and has a significant shortage of highly qualified personnel that can work in ground control. The program will contribute significantly to the training of graduate students who will gain theoretical knowledge and field experience applying fundamental principles to solve real problems at mines.