Study on physical characteristics of anthracite under high temperature triaxial action

Abstract

During and after the in-situ mining of anthracite coalbed methane, the influence of temperature on anthracite coal has become an important factor in judging whether a project can be implemented. In this paper, the stress-strain curves of anthracite at 10 MPa hydrostatic pressure and different temperatures, stress-strain curves at 300 ℃ and different hydrostatic pressures, the stress-strain curves of anthracite under different hydrostatic pressures under temperature rise of 500 ℃ and then slow cooling to 300 ℃, were studied by using the servo experiment device independently developed by the Key Laboratory of In-situ Modified Mining of Ministry of Education, Taiyuan University of Technology. The results show that during the process of heating up, anthracite exhibits different thermal expansion laws under different hydrostatic pressure conditions. The greater the hydrostatic pressure, the smaller the thermal deformation; as the temperature increases, the elastic modulus and peak strength of anthracite will decrease accordingly; the confining pressure will enhance the strength of anthracite, which is specifically expressed in that with the increase of hydrostatic pressure, the elastic modulus and peak strength of anthracite will increase; the weakening effect of high temperature on anthracite is irreversible. The performance is that when anthracite is directly heated to 300 °C, the cohesion and internal friction angle of the two are different from that of anthracite when the temperature is raised 500 °C and then lowered to 300 °C. This paper uses orthogonal experiments to fit the elastic modulus of anthracite within 15 MPa and 300 ℃ as a function of confining pressure and temperature.

Keywords

• high temperature and high pressure
• anthracite
• peak intensity
• thermal expansion
• elasticity modulus