Quantitative analysis of the influence of temperature and confining pressure on brittleness of granite: A review

Abstract

In order to quantitatively study the influence of temperature and confining pressure on brittle plasticity of granite, this paper reviews previous studies regarding quantitative calculation methods for the brittle-plastic behaviors of rocks and their mechanical characteristics under high temperatures and confining pressures. Combining the experimental results for temperatures and confining pressures with theoretical calculations of brittleness and plasticity allowed quantitative calculations and evaluations for the brittleness and plasticity of granite to be obtained. The main conclusions are as follows. (1) High temperatures lead to a transformation of granite from brittle failure to plastic failure. Comparing six conventional empirical equations from the literature, the B3 and B6 can more accurately describe the relationship between the brittleness and temperature of granite. (2) When the confining pressure σ3 is less than 20 MPa, the internal pore structure and fractures of granite are re-compacted and reduced, which gradually increases its brittleness. With the increasing confining pressure, the pore structure changes again after exceeding 20 MPa. This initiates new cracks, which ultimately leads to a decrease of the granite brittleness. (3) The abrupt temperature for the brittle-plastic transformation of granite is approximately 800 °C, and the brittle-plastic transformation of granite is mainly affected by temperature and not the confining pressure. ARTICLE INFO