Fractal Characteristics of Rock Fracture Surface under Triaxial Compression after High Temperature

Abstract EN

Scanning Electron Microscopy (SEM) test on 30 pieces of fractured granite has been researched by using S250MK III SEM under triaxial compression of different temperature (25~1000°C) and confining pressure (0~40 MPa).

Research results show that (1) the change of fractal dimension (FD) of rock fracture with temperature is closely related to confining pressure, which can be divided into two categories.

In the first category, when confining pressure is in 0~30 MPa, FD fits cubic polynomial fitting curve with temperature, reaching the maximum at 600°C.

In the second category, when confining pressure is in 30~40 MPa, FD has volatility with temperature.

(2) The FD of rock fracture varies with confining pressure and is also closely related to the temperature, which can be divided into three categories.

In the first category, FD has volatility with confining pressure at 25°C, 400°C, and 800°C.

In the second category, it increases exponentially at 200°C and 1000°C.

In the third category, it decreases exponentially at 600°C.

(3) It is found that 600°C is the critical temperature and 30 MPa is the critical confining pressure of granite.

The rock transfers from brittle to plastic phase transition when temperature exceeds 600°C and confining pressure exceeds 30 MPa.