Long reinforcement strategies for underground mines

对矿产资源的需求增加，导致开采更深的矿石储量，并使用生产率更高的采矿方法。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受伤的最大原因，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内深处时，传统的岩石锚杆是不够的，必须使用更长的加固单元，如缆索螺栓来支撑开挖。缆索锚杆是由多股钢丝组成的大容量柔性地筋。它们的性能主要是通过实验室测试确定的，很难根据现场条件推断它们的结果。锚索锚固策略是基于理想条件下的经验方法，只包括几种可用的锚杆类型，并不适用于所有的开挖墙。仪表式电缆螺栓提供了有关电缆性能的有用信息，但没有完全集成到支撑设计中。数值模拟可以补充仪器数据，为开发电缆锚杆策略提供合理和可靠的方法。这就要求我们对锚索螺栓的行为有一个很好的了解，并且数值模型可以再现不同条件下各种类型的锚索螺栓的显式行为。拟议的研究计划旨在通过在进入和不进入的地下开挖中进行现场拉拔试验和现场试验，提高我们对不同类型电缆锚杆性能的理解。现场监测，包括先进的3D激光扫描方法、引伸仪和仪表化螺栓，将允许表征不同类型和配置的电缆螺栓在不同现场条件下的性能。复杂的3D数值模拟方法将被用来明确地捕捉不同电缆的性能以及在进入和不进入挖掘的不同阶段中的3D破坏区域。该程序将建立在我之前关于使用仪器和先进的岩石破坏机制和加固行为的显式模型的工作的基础上。这将使我们能够增加对电缆的现场和机械行为的知识。研究结果将为电缆螺栓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训研究生，他们将获得理论知识和现场经验，应用基本原理来解决矿山的实际问题。

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.