Abstract
A hybrid finite-discrete element method is proposed to model the rock fracture under various loading conditions. The key component of the hybrid method, i.e. transition from continuum to discontinuum through fracture and fragmentation, is introduced in detail. An empirical relationship between the static strengths and the dynamic strengths derived from the dynamic rock fracture experiments is implemented in the hybrid method to model the effect of loading rate. The hybrid method is calibrated by modelling the Brazilian tensile strength (BTS) test, uniaxial compressive strength (UCS) and notched Brazilian dis tests. Then the hybrid method is employed to model the dynamic rock fracture process in UCS and BTS tests. The proposed method has well modelled the dynamic rock fracture and fragmentation processes and captured the effect of loading rate on rock strengths. It is concluded that the hybrid finite-discrete element is a valuable tool to study the dynamic rock fracture as it takes the advantages of the continuum and discontinuum based method, and considers the effect of loading rate.
Highlights
In the hybrid finite-discrete element modelling of the dynamic rock fracture process using various test techniques, the effect of loading rate is taken into account by through implementing an empirical relation between the static strengths and the dynamic strengths derived from the dynamic rock fracture experiments (Zhao 2000)
Brazilian tensile strength (BTS) test is developed to determine the tensile strength of brittle materials indirectly using cylindrical specimen since conventional methods of tensile test present difficulties to cope with low tensile resistance materials, such as concrete, rock, and rock-like materials
The transition from continuum to discontinuum through fracture and fragmentation makes the hybrid method superior to the traditional continuum-based finite element method and discontinuum-based discrete element method
Summary
The fracture, failure and collapse of rock-like materials have been studied widely since it is significant to understand the fracture mechanism in civil engineering and mining engineering and several other files in which rock fractures play an important role (An and Liu 2014, Liu and An 2016, An, Liu et al 2017a, An, Liu et al 2017b, An, Hou et al 2019, Fukuda, Mohammadnejad et al 2019a). The hybrid finite-discrete element method (FDEM) proposed by Munjiza (2004) may be the most widely used hybrid continuum-discontinuum method It takes the advantages of continuum method and discontinuum method and can model the transition process of rock from continuum to discontinuum trough rock fracture and fragmentation (An and Liu 2014, An, Liu et al 2017a). The modelling of the dynamic rock fracture process is used to show the ability of the proposed method to capture the rock characteristics on loading rates during the dynamic rock fracture process
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