Zhennan Zhu

China University of Mining and Technology · School of Mechanics and Civil Engineering

Understanding the mechanical responses of granites after various thermal shocks is of utmost significance for heat extraction through from enhanced geothermal systems (EGSs). In this research, the changes in the mechanical characteristics of granites after various thermal shocks are analyzed and determined following according to a comprehensive rev...

Given the major impact of thermal treatment on the deformation and failure characteristics of rocks in deep rock engineering, it is crucial to understand the relevant behaviors of rocks with the temperature effect being taken into account. For this purpose, the deformation of rocks after exposure to high temperature is divided into void and skeleto...

The evaluation of physico-mechanical characteristics of rocks after thermal treatment is a key issue in underground rock engineering projects such as exploitation of geothermal resources and geological disposal of nuclear waste. In this research, the lengths of cylindrical Nanan granite specimens were obtained before, during and after thermal treat...

Understanding the drillability indices of thermal granite under various water-cooling conditions is of great significance for deep drilling and wellbore stability during the extraction of deep geothermal energy. In this paper, we report the results of micro-drilling tests, indentation hardness tests, friction-and-wear tests as well as conventional...

During drilling, reservoir fracturing and hot dry rock development, high-temperature rock is subjected to cyclic water cooling. The mechanical properties and microscopic characteristics of granite exposed to high-temperature and water-cooling cycles were investigated experimentally. The results show that the uniaxial compressive strength and elasti...

On the basis of Lemaitre’s strain equivalence theory, the effects of high temperatures on the mechanical parameters of rock are taken into account, and a thermal damage variable DT is introduced. A statistical thermal damage constitutive model is developed by adopting the modified Mohr-Coulomb criterion with the hypothesis that the mesoscopic unit...

Water has been used as a working fluid injected into the hot reservoirs during the exploitation of deep geothermal energy, therefore, understanding the thermomechanical properties of reservoir rocks after water cooling is essential. For that reason, we have conducted a series of laboratory tests on air and water cooled granites from normal temperat...

Understanding the mechanical behaviors of granite after thermal treatment under loading and unloading conditions is of utmost relevance to deep geothermal energy recovery. In the present study, a series of loading and unloading triaxial compression tests (20, 40 and 60 MPa) on granite specimens after exposure to different temperatures (20, 200, 300...

Understanding the mechanical behaviors of granite after high temperature exposure and under confining stress conditions is an important issue in deep rock engineering projects such as the mining of deep underground solid mineral resources, deep geothermal energy exploitation and deep nuclear waste repositories. In this research, conventional triaxi...

The bedrocks of deep geothermal reservoirs are exposed to cyclic water cooling during the exploitation of deep geothermal energy. Therefore, it is important to understand the physico-mechanical parameters of geothermal reservoir rocks. This paper reports on the P-wave velocity (Vp), uniaxial compressive strength (UCS) and elastic modulus (E) of gra...

A deep understanding of the physico-mechanical characteristics of rocks undergoing thermal treatments has gained a great interest in deep rock projects. In this research, the size and mass of cylindrical granite samples were measured before, under and after a temperature up to 1000°C, and their bulk densities at different temperature levels were ca...

Laboratory tests were conducted to study the physical and mechanical properties of granite after heating and water-cooling treatment for 1 and 30 cycles from room temperature to 500 °C. The change mechanisms for the water-cooling treatment were analysed via scanning electron microscope observation. At 500 °C, the volume of granite increases by 1.73...

Geothermal energy is recommended as a clean and renewable energy resource. During the exploitation process, hot rocks in a geothermal reservoir will be subjected to cyclic water cooling. Laboratory tests were conducted to investigate the physical and mechanical behaviors of water-cooled granite specimens subjected to various thermal cycles with tem...

Laboratory tests are conducted to study the physico-mechanical properties of water cooling treated granite under room temperature to 500 ℃. Variations of physico-mechanical properties are analyzed in detail. Meanwhile, the physico-mechanical changing mechanisms of water cooling treated granite are revealed by the pictures of scanning electron micro...