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

在采矿和土木工程应用中越来越多地使用离散断裂网络（DFN）模型的基础上，提出的研究有两个主要的相互关联的主题，这两个主题可以并行发展。第一个课题包括研究断裂长度和体积断裂强度之间的关系，试图定量定义这些参数与岩体自然破碎之间的关系。预计这项初步工作将在帮助确定需要模拟地质力学合成岩体模型以完全捕获自然断裂岩体的代表性基本体积（REV）的尺度方面具有重要意义。第二个专题涉及集中于崩落前评价，特别是岩体破碎，因为崩落不良或意外破碎对洞穴作业的影响是一个重要的工程和经济因素。迄今为止的研究已经证明，DFN工具可以有效地帮助进行破碎性评估，主要是通过更好地描述原位岩体的自然破碎性。然而，对初级和次级碎片化的评价仍在使用主要基于实际经验的替代方法进行，试图使用经验推导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。本文认为，基于DFN的岩体模型的综合测试，通过岩石破碎的混合有限/离散元模拟，可以有效地用于更好地捕捉破碎机制，并开发一种辅助采矿和民用应用中的破碎评估的替代方法。所提出的方法不仅依赖于充分捕捉岩体更广泛的非均质性的能力，而且更重要的是依赖于确定从完整的大块岩体向运动可动岩体过渡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.