关键词: 颗粒流理论, 岩石, 加载速率, 失效机制, 声发射

Abstract: Mechanical properties of rocks at different loading rates have positive effects on their inner failure mechanisms under dynamic loading conditions. Numerical simulations of uniaxial compression and Brazilian tests are conducted on granite specimens using the bonded particle model (BPM) in particle flow code (PFC2D). To quantify rate-dependent behavior of compression strength, tensile strength, failure modes, strain energy rate and acoustic emission, four different loading rates are chosen from 0.001 to 0.500 m/s. The uniaxial compression strength (UCS) and its corresponding strain, and the tensile strength and its corresponding strain increase nonlinearly with loading rate. The failure pattern and damage degree are also influenced by the loading rate. It is found that specimens under compressive loading have a single inclined section at a lower loading rate, while have several oblige section forms at a higher loading rate. In addition, crack numbers and high horizontal strain rate distributions show that the failure zone area and damage degree increase with increasing loading rate. In Brazilian tests, the failure modes change from one primary crack to several major cracks as loading rate increases. Cracks extend to the edge of circle specimens, and loading rate exacerbates damage degree. Additionally, acoustic emission counts and strain energy rates of specimens in both tests increase in nonlinear forms with increasing loading rate.

Key words: particle flow theory, rock, loading rate, failure mechanism, acoustic emission