Mechanical characteristics and energy properties of granite under uniaxial compression after high temperature have been researched. The results show that energy conversion during rock deformation and failure is a dynamic process, and it can be mainly divided into four subprocesses: energy input, energy accumulation, energy dissipation and energy release. Thermal damage defined by elastic modulus increases generally but has volatility, which can be fitted into cubic curve. Rock strength shows inverse ratio to dissipated energy and proportional ratio to elastic energy, energy dissipation makes the material deteriorate and its strength drop down eventually. Acoustic emission energy rate shows proportional ratio to elastic energy and inverse ratio to dissipated energy, the elastic energy released in rock volume plays the pivotal role of abrupt structural failure of rock. It is emphasized that the failure of rock is a process in which energy dissipation and energy release occur simultaneously.

1. Introduction

Rock is a special geological material,which physical and mechanical characteristics affected by geology usually represent anisotropism and nonlinearity. Rock distortion and fracture is an energy dissipation irreversible process, so stress analysis can not reflect the law of rock failure. Rock may be failure in a stress range, stress is not the essence factor which token strength of rock. The token of rock strength must be considered from the energy dissipation and analyzed from the micro-defect evolvement during the entirely process. So far, some scholars have reasearched rock mechanical behavior under dynamic load, a lot of valuable fruits have been gotten. The inner link of rock energy dissipation, energy releasing and the whole structure stability have been studied by Xie he ping. Mechanical characteristics and energy properties of granite under uniaxial compression after high temperature have been researched.

2 Experimental Condition and Method

In our investigation, we have used cylindrical rock specimens, 50mm long with diameters of 25 mm. There were 45 specimens in total, divided into nine groups with 3 specimens to each group. First, the specimens of each group were heated to the temperature of 25, 50, 100, 200, 300, 400, 500, 600, 700, 800, 900, 1000, 1100, 1200 and 1300° separately. In each case, the temperature was kept constant for 20 min so that the specimens could be heated to the assigned value from the outside to the inside and then the specimens were taken out and cooled down in the air. The experiment used displacement control mode, and the loading rate is 0.0015 mm/s.

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