Deterioration of equivalent thermal conductivity of granite subjected to heating-cooling treatment  

作　　者：Mohua Bu Peng Zhang Pingye Guo Jiamin Wang Zhaolong Luan Xin Jin 

机构地区：[1]State Key Laboratory for Geo-Mechanics and Deep Underground Engineering,China University of Mining and Technology(Beijing),Beijing,100083,China [2]School of Mechanics and Civil Engineering,China University of Mining and Technology(Beijing),Beijing,100083,China [3]School of Qilu Transportation,Shandong University,Jinan,250001,China [4]Academy of Deep Earth Sciences,Chinese Institute of Coal Science,Beijing,100013,China [5]China State Key Laboratory of Coal Mining and Clean Utilization,China Coal Technology and Engineering Group,Beijing,100013,China

出　　处：《Journal of Rock Mechanics and Geotechnical Engineering》2024年第10期4229-4246,共18页岩石力学与岩土工程学报（英文）

基　　金：the Natural Science Foundation of China(Grant No.42241145);supported by the Natural Science Foundation of China(Grant No.41941018);General Projects for Scientific and Technological Innovation of China Coal Science and Industry Group(Grant No.2022-MS001).

摘　　要：Understanding the thermal conductivity of granite is critical for many geological and deep engineering applications.The heated granite was subjected to air-,water-,and liquid nitrogen(LN2-)coolings in this context.The transient hot-wire technique was used to determine the equivalent thermal conductivity(ETC)of the granite before and after treatment.The deterioration mechanism of ETC is analyzed from the meso-perspective.Finally,the numerical model is used to quantitatively study the impact of cooling rate on the microcrack propagation and heat conduction characteristics of granite.The results show that the ETC of granite is not only related to the heating temperature,but also affected by the cooling rate.The ETC of granite decreases nonlinearly with increasing heating temperature.A faster cooling rate causes a greater decrease in ETC at the same heating temperature.The higher the heating temperature,the stronger the influence of cooling rate on ETC.The main explanation for the decrease in ETC of granite is the increase in porosity and microcrack density produced by the formation and propagation of pore structure and microcracks during heating and cooling.Further analysis displays that the damage of granite at the heating stage is induced by the difference in thermal expansion and elastic properties of mineral particles.At the cooling stage,the faster cooling rate causes a higher temperature gradient,which in turn produces greater thermal stress.As a result,it not only causes new cracks in the granite,but also aggravates the damage at the heating stage,which induces a further decrease in the heat conduction performance of granite,and this scenario is more obvious at higher temperatures.

关 键 词：Equivalent thermal conductivity(ETC) GRANITE Heating-cooling treatment Pore structure MICROCRACK Grain-based model 

分 类 号：TU41[建筑科学—岩土工程]