Application of aperture dependent model in thermal cracking of rock
LI Mengyi1，2，WU Zhijun1，2，ZHOU Yuan1，2，LIU Quansheng1，2，SHEN Jianqiang3
(1. School of Civil Engineering，Wuhan University，Wuhan，Hubei 430072，China；2. The Key Laboratory of Safety for Geotechnical and Structural Engineering of Hubei Province，Wuhan University，Wuhan，Hubei 430072，China；3. Zhejiang Jiaogongluqiao Construction Co.，Ltd.，Hangzhou，Zhejiang 315101，China)
Abstract：The primary fractures of the rock would hinder heat flux flowing and redistribute temperature field，which in turn affect the thermal stress distribution inside the rock and lead to the cracking of the rock. Therefore，it is of great significance to investigate the mechanism of heat conduction and thermal cracking of multi-fractured rocks under high temperature. In this study，the particle flow code was adopted to simulate the dynamic process of heat transfer-crack inside the rock. Firstly，considering the difference in mineral composition inside the rock，the cluster model was adopted to characterize the meso-structure and composition distribution of the rock，and then the mesoscopic parameters were calibrated. Secondly，to more realistically simulate the influence of internal fractures on heat flux flowing and thermal cracking，the thermodynamic properties of cracks were assumed to be the aperture dependent，and the thermal and meso-mechanical parameters of the fracture were calibrated through the analytical solutions of macroscopic parameters under different fracture aperture conditions. Correspondingly，the aperture dependent models for thermal parameter and meso-mechanical parameter were proposed，respectively. Finally，combined with the random fracture network，the influence of the fracture aperture distribution on the thermal conduction and thermal cracking in multi-fractured rocks were investigated，in which the fracture aperture distribution was controlled by different shape parameters m .The results showed that with the increase of shape parameter m，the time cost for the thermal conduction reaching the steady-state was gradually reduced while the rate of thermal crack initiation increased. The feasibility of the proposed aperture-dependent model in simulating the thermal conduction and thermal cracking in multi-fractured rocks were also verified.
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2019, Vol. 38 
