化学浸泡作用下热冲击花岗岩物理特性与导热性能演化机制  

Evolution mechanism of the physical properties and thermal conductivity of thermal shock granite under chemical immersion

作　　者：潘继良 郭奇峰[1,2] 任奋华[1,2] 张英[1,2] 武旭 PAN Ji-liang;GUO Qi-feng;REN Fen-hua;ZHANG Ying;WU Xu(School of Civil and Resources Engineering,University of Science and Technology Beijing,Beijing 100083,China;Key Laboratory of High Efficient Mining and Safety of Metal Mines(Ministry of Education),University of Science and Technology Beijing,Beijing 100083,China;Beijing Municipal Engineering Research Institute,Beijing 100037,China)

机构地区：[1]北京科技大学土木与资源工程学院,北京100083 [2]北京科技大学金属矿山高效开采与安全教育部重点实验室,北京100083 [3]北京市市政工程研究院,北京100037

出　　处：《工程科学学报》2022年第10期1755-1766,共12页Chinese Journal of Engineering

基　　金：中国工程院重点咨询项目(2019-XZ-16);中央高校基本科研业务费专项资金资助项目(FRF-IDRY-20-032)。

摘　　要：为了研究化学浸泡作用下热冲击花岗岩物理特性与导热性能演化特征,对25~600℃范围内不同温度热冲击作用后的花岗岩试件开展了长期的酸性和中性溶液浸泡试验,结合超声检测、核磁共振测试、热常数分析和扫描电镜试验,定量表征了热化改性花岗岩试件物理参数随热冲击温度的演化规律,建立了各物理参数之间的内在关联性,揭示了物理性质变化的微观机制.研究结果表明:随着热冲击温度的升高,热化改性试件的体积逐渐增大,质量和密度逐渐降低,纵波波速呈线性下降,孔隙率呈幂函数递增,导热系数和热扩散系数分别呈指数下降和线性下降;相同热冲击温度下,热化改性试件的体积增长率、纵波波速和导热系数由大到小依次为未浸泡>水浸泡>酸浸泡,质量降低率和孔隙率从高到低依次为酸浸泡>水浸泡>未浸泡;孔隙率增大和导热性能劣化均伴有纵波波速的下降,可通过测量纵波波速对孔隙率和导热性能进行估测;热化改性试件的孔隙结构对150~450℃范围内的温度更为敏感,固体颗粒骨架对450℃以上温度更为敏感,颗粒骨架的劣化又将进一步引起孔隙结构的演化;热化改性作用引起的微观孔隙结构发育和物相转变是导致物理性质变化的本质原因,其中以高温热冲击起主导作用,研究发现300℃可作为产生强烈热冲击的温度阈值.To exploit the geothermal energy from low penetration rocks at a depth of 3–10 kilometers below the ground surface,an artificial geothermal system usually must be built.Thermal and chemical stimulation can be used as auxiliary means of hydraulic fracturing for artificial geothermal reservoir reconstruction,which is conducive to reducing the risk of earthquakes.However,thermal shock and chemical corrosion can also cause changes in physical parameters such as density,porosity,longitudinal wave velocity,and t he thermal conductivity of high-temperature rock mass,which brings great uncertainty to the service life of a geothermal system.To study the evolution of the physical properties and thermal conductivity of thermal shock granite under chemical modification,long-term acid and neutral solution immersion tests were performed on granite specimens subjected to thermal shock at temperatures ranging from 25℃to 600℃.Using ultrasonic testing,nuclear magnetic resonance,thermal constant testing,and scanning electron microscopy,the evolution of the physical parameters of thermal-chemical modified specimens with thermal shock temperature was quantitatively characterized,the internal correlation among physical parameters was established,and the microscopic mechanism of the change in physical properties was revealed.The results show that with increasing thermal shock temperature,the volume of thermal–chemical-modified specimens increases gradually,the mass and density decrease gradually,the longitudinal wave velocity decreases linearly,the porosity increases by a power function,and the thermal conductivity and thermal diffusivity decrease exponentially and linearly,respectively.At the same thermal shock temperature,the volume growth fraction,longitudinal wave velocity,and thermal conductivity of the modified specimens are in the order of non-immersion>water immersion>acid immersion,while the mass loss fraction and porosity are in the order of acid immersion>water immersion>non-immersion.The increase in porosity and the

关 键 词：高温花岗岩 热冲击 化学腐蚀 纵波波速 孔隙率 导热系数 

分 类 号：TU458.2[建筑科学—岩土工程]