A Discrete Fracture Network approach to rock mass characterization and assessment of rock fragmentation for cave mining.

基于离散断裂网络(DFN)模型在采矿和土木工程应用中越来越多的使用，拟议的研究有两个主要的相互关联的主题，可以并行发展。第一个主题包括研究裂隙长度和体积裂隙强度之间的关系，试图定量地确定这些参数与岩体自然破碎的关系。预计这项初步工作将对确定地质力学合成岩体模型需要模拟以完全捕捉自然裂隙岩体的代表基本体积(REV)的比例具有重要意义。第二个专题侧重于崩塌前的评估，特别是岩石破碎，因为不良的或意外的破碎对洞穴作业的影响是一个重要的工程和经济因素。迄今为止的研究肯定有助于证明，DFN工具可以有效地协助破碎评估，主要是通过更好地描述原位岩体的自然破碎。然而，仍在使用主要基于实践经验的替代方法对初级和次级碎片化进行评估，试图使用经验得出的规则来描述这些过程，而不是直接解决所涉及的过程和机制。基于DFN的岩体模型的综合测试，通过有限元/离散元的岩石破裂混合模拟，可以有效地用于更好地捕捉破碎机理，并开发一种替代方法来辅助采矿和民用应用中的破碎评估。所提出的方法不仅取决于完全捕捉更广泛的岩体非均质性的能力，更重要的是取决于确定从完整的块状岩体向运动的可动岩体转变的临界断裂强度值的能力。

Building on the increasing use of Discrete Fracture Networks (DFN) models in both mining and civil engineering applications, the proposed research has two major inter-related topics, which could be developed in parallel. The first topic includes studying the relationship between fracture length and volumetric fracture intensity in an attempt to quantitatively define the relationship between these parameters and the rock mass natural fragmentation. It is expected that this initial work will have a significant importance in helping defining the scale at which geomechanical synthetic rock mass models need to be simulated to fully capture the Representative Elementary Volume (REV) of a naturally fractured rock mass. The second topic involves focusing on pre caving assessment and in particular on rock mass fragmentation, since the impact of poor or unexpected fragmentation upon cave operations represents a significant engineering and economics factor. Research to date has certainly contributed to demonstrate that DFN tools can effectively assist in the fragmentation assessment, primarily through providing a better description of the natural fragmentation of the in-situ rock mass. However, the evaluation of primary and secondary fragmentation is still being carried out using alternative methods mostly based on practical experience, attempting to describe these processes using empirically derived rules rather than a direct solution of the processes and mechanisms involved. It is believed that synthetic testing of DFN based rock mass models, by means of hybrid Finite/Discrete Element simulation of rock breakage, can be effectively used to better capture fragmentation mechanisms and develop an alternative approach to aid fragmentation assessment in mining and civil applications. The proposed approach would rely not only on the ability to fully capture the broader heterogeneity of the rock mass, but more importantly on the ability of determining a critical fracture intensity value at which the transition from intact massive rock mass to kinematically mobile rock mass occurs.