Experimental Technology and Management

在绿色低碳能源领域的干热岩开采中，岩石力学性能在温度冲击作用下的演化直接影响开采效率。该文采用物理实验和数值模拟相结合的方法，构建了温度冲击作用下岩石力学实验教学平台。利用岩芯试样经不同高温处理后的单轴压缩实验，获得了基本力学参数随温度的演化规律；基于声发射信号反映岩石内部的损伤信息，获得了加载过程中的损伤变量曲线。开展了高温岩石力学性能的PFC模拟，以物理实验结果为依据进行了参数标定，通过可视化分析获取了颗粒间裂纹的图像。该实验平台可以推动教学内容更新，形成良性循环，有利于提升学生的实践能力和创新能力。

[Objective] Hot dry rock is a type of renewable energy that is widely distributed in the deep layers of the Earth's crust. Its exploitation can play a significant role in promoting the diverse and sustainable development of China's energy sector. However, when underground hot rock mass comes into contact with low-temperature working fluid, the mineral particles will shrink sharply, resulting in thermal stress and changing the physical and mechanical properties of the reservoir rock, which affects the connectivity rate of the fracture network. In this paper, an acoustic emission experiment under uniaxial compression and particle flow code(PFC) numerical simulations are combined to build a teaching platform for rock mechanics experiment under temperature shock, which can not only reduce the experimental cost and shorten the research period but also help to cultivate students' innovative spirit and practical ability. [Methods] The uniaxial compression test of granite samples is carried out by an SHT4 series electrohydraulic servo universal testing machine, and the acoustic emission test is carried out by the SAEU3H system produced by Beijing Shenghua Technology Company. The variation of peak compressive strength, elastic modulus, and Poisson's ratio with temperature is obtained according to the stress–strain curves of granite treated at different temperatures. The damage variable is calculated by using the energy value of the acoustic emission signal, and the different crack development stages are divided according to the damage variable curve. The effect of temperature change on the particles is realized by changing the thermal expansion radius of the granite, using the high-temperature treatment module that comes with the PFC software. The peak stress of the granite sample and its corresponding strain value are selected as the calibration objectives, and the parameters of effective modulus, normal strength, and stiffness ratio in the simulation process are gradually adjusted to make them approach the optimal value. Combined with the crack simulation diagram and the particle slip diagram, the failure mode of granite under the influence of high temperature is analyzed. [Results] The research results show that the peak compressive strength of granite increases first and then decreases with the increase in temperature, the elastic modulus decreases with the increase in temperature, and the Poisson's ratio increases with the increase in temperature, which indicates that high-temperature treatment enhances the plasticity of granite. When crack propagation enters the stable phase, the damage variable curve begins to rise, and new cracks initiate. As cracks further extend and coalesce, the damage variable starts to accumulate at an accelerated rate, marking the transition into the intensified crack propagation stage. The PFC simulation results show that when the treatment temperature is less than or equal to 250 ℃, the cracks show a vertical trend, and the failure of rock samples is mainly in the form of splitting; when the treatment temperature is greater than or equal to 450 ℃, the crack direction is inclined, and the failure mode is mainly shear. [Conclusions] This paper takes hot dry rock mining in the field of green and low-carbon energy as the engineering background, takes the evolution mechanism of rock formation mechanical properties under the action of temperature shock as the technical background, and combines the needs of experimental teaching in engineering colleges and universities to establish a rock mechanics experimental teaching platform that combines physical experiment and numerical simulation. Physics experiments can improve students' practical operation ability and obtain the real mechanical parameters of rocks treated at different temperatures. Through the analysis of crack images in PFC numerical simulation, students can deepen their understanding of the physical mechanics principles behind it. This teaching platform is conducive to improving students' ability to comprehensively apply theoretical knowledge and experimental results to solve engineering problems.