摘要
高温作用会导致岩石内部结构发生变化,并对其热物理性质有着显著影响。因此,研究高温作用后岩石热物理性质的变化规律对地热系统及存在热流传播问题的地下工程具有指导意义。试验利用高温炉和Hot Disk热常数分析仪研究了高温作用后砂岩热物理性质的变化特征。研究表明:砂岩的热导率、比热、热扩散率随温度整体呈下降趋势,可分为25℃~100℃,100℃~400℃,400℃~600℃,600℃~900℃四个阶段;25℃~100℃,砂岩热导率、比热、热扩散率因附着水蒸发急剧减小;100℃~400℃,砂岩热导率、热扩散率变化平缓,比热因含水量的降低减小得较快;400℃~600℃,砂岩中结晶水、结构水的蒸发及石英的相变导致微裂隙发育、延伸,进而引起热导率、比热、热扩散率持续下降;600℃~900℃,砂岩中矿物发生分解、熔融破裂,热破裂进一步增加与扩展,这个阶段内热导率、比热迅速下降,但热扩散率基本稳定。
The internal structure and thermal physical properties of rocks can change under high temperature heating. Therefore, the research on the changes of the thermal physical properties of rocks after high temperature heating can provide guidance to the geothermal system and underground engineer- ing associated with heat flow transmission. In this work, we used a hot disk thermal constant analyzer and high temperature furnace to perform an experi- ment to study thermal physical properties of sandstone after high temperature heating. The results show that the therma] conductivity of the sandstone de- creases with the increasing temperature as a whole, which can be divided into four stages： 25℃ to 100℃ , 100℃ to 400℃ ,400℃ to 600℃ and 600℃ to 900℃. The thermal conductivity, specific heat, and thermal diffusivity of the sandstone decrease sharply due to the evaporation of attached water when the temperature rises from 25＂C to 100℃. When the temperature goes up from 100℃ to 400℃ , the thermal conductivity and thermal diffusivity of the sand- stone ehange gently. In contrast, the specific heat decreases quickly because of the reduction of water content. The thermal conductivity, specific heat, and thermal diffusivity of the sandstone decline with the evaporation of crystal water and strueture water and phase transition of quartz, leading to the devel- opment and extension of micro -fractures after 400℃. In the stage of 600℃ to 900℃ , thermal cracking is further intensified and expands due to mineral decomposition and melt rupture in the sandstone. So the thermal conductivity and specific heat of the sandstone decrease rapidly. However, the thermal diffusivity is basically stable when the thermal conductivity and specific heat decline.
出处
《地质与勘探》
CAS
CSCD
北大核心
2017年第4期780-787,共8页
Geology and Exploration
基金
国家自然科学基金面上项目(编号:41672279)资助
关键词
砂岩
高温作用
热导率
比热
热扩散率
sandstone, high temperature, thermal conductivity, specific heat, thermal diffusivity
