Study on the Fractal Dimension of Rock Fracture Surface after Different Temperatures

Abstract

In order to study the relationship between the fractal dimension of rock fracture surface and temperature, uniaxial compression experiments on the granite rock and scanning electron microscopy experiments on the rock fracture surface were carried out after different temperatures. The fractal dimension was calculated by using scanning electron microscopy images. The results are as following: (1) The cracks show intergranular damage like rock candy, rivers and so on at the temperature from 25°C to 200°C. The fractal dimension are volatile, the fractal dimension reach the maximum at 200 °C, it can be inferred that the granite rock burst the most energy consumption at 200 °C; (2) From 200°C to 800°C, the cracks transform from stepped cleavage, intergranular fracture gradually to grain crushing, transgranular cracking damage with the rise of temperature. When the temperature is above 800 °C, the cracks transform from the transgranular cracks, shear slip bands gradually to dimples and microporous points. The cracks of rock surface transform from irregular crack structure to homogeneous pore structure gradually at high temperature, the weakening of rock heterogeneity is the basic reason for the decrease of fractal dimention of rupture surface, the fractal dimension is reduced from 1.634 at 200 °C to 1.595 at 1200 °C, the margin of reduction is 2.39%. At the same time, the energy consumption of rock rupture decreases with the rise of temperature, rock transforms from brittle to plastic gradually.