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In order to study the long-term mechanical properties of dry hot rocks in thermal reservoir, the time-dependent micromechanical deformation of granite was studied by grid micro-indentation creep test. The results show that the indentation points of granite show obvious creep deformation under constant load. The fractional Maxwell model composed of spring elements and Abel pot in series can describe the time-dependent deformation of granite under constant pressure. The relationship between the micromechanical parameters obtained by grid micro-indentation test and the composition and macro mechanical parameters of granite is not clear, which needs further study. At the same time, as a new quantitative evaluation method of rock micromechanical properties, micro-indentation test technology has a good application prospect in rock mechanical parameters assessment. [ABSTRACT FROM AUTHOR]

In the utilization of fluid media to generate power with hot dry rock（HDR）, the rock layers with different temperature gradients generally produce alternating temperature changes. Therefore, studying the permeability of rocks under the effects of cyclic high temperature conditions can help enhance its utilization efficiency. By experimentally exploring granite’s gas permeability under the effect of cyclic high temperature cooling（HTC, carried out at 400 ℃ and 600 ℃）, the influences of factors such as temperature, number of cycles, cooling methods and confining pressures on fluid transmission within granite were discussed, on which basis the evolutionary pattern of granite’s gas permeability under cyclic HTC was analyzed from different perspectives. The results show that as the number of cycles and temperature increased, the deterioration experienced by the rock specimens also become significant. Moreover, it is also found that the deterioration levels caused by high temperature quenching are serious higher than cooling by radiation. Rock damage peaks in severity after the first round of HTC, with mass loss taking up about half of the total mass loss after 6 cycles. Furthermore, the apparent permeability of the rock specimens also increases by two orders of magnitude (from 10-18 m~2 to 10-16 m²) after 2 cycles. At the 4th and 6th cycles, the growth of apparent permeability slows down under high temperature quenching, but changes are negligible when cooled by radiation. [ABSTRACT FROM AUTHOR]