循环热冲击后裂隙砂岩力学特性试验研究  

Mechanical properties of fractured sandstone after cyclic thermal shock

作　　者：李满 刘先珊[1,2,3] 潘玉华 乔士豪 郝梓宇 钱磊 罗晓雷 LI Man;LIU Xian-shan;PAN Yu-hua;QIAO Shi-hao;HAO Zi-yu;QIAN Lei;LUO Xiao-lei(Key Laboratory of New Technology for Construction of Cities in Mountain Area,Ministry of Education,Chongqing University,Chongqing,400045,China;School of Civil Engineering,Chongqing University,Chongqing,400045,China;National Joint Engineering Research Center of Geohazards Prevention in the Reservoir Areas,Chongqing University,Chongqing 400045,China)

机构地区：[1]重庆大学山地城镇建设与新技术教育部重点实验室,重庆400045 [2]重庆大学土木工程学院,重庆400045 [3]重庆大学库区环境地质灾害防治国家地方联合工程研究中心,重庆400045

出　　处：《岩土力学》2023年第5期1260-1270,共11页Rock and Soil Mechanics

基　　金：国家自然科学基金(No.52279094);广西重点研发计划(桂科AB20238036)。

摘　　要：砂岩热储层的改造和长期稳定性评价对地热能源开发具有重要意义。研究了裂隙砂岩在0~8次热冲击作用下的力学特性。试验结果表明:随着热冲击次数的增加,两种冷却方式下裂隙砂岩的纵波波速、单轴抗压强度和弹性模量均逐渐减小。与水冷却相比,空气冷却对裂隙砂岩物理力学特性的劣化较弱,单轴抗压强度和弹性模量与热冲击次数呈现较好的指数函数关系。纵波波速和弹性模量均能很好地表征裂隙砂岩随热冲击次数的损伤,其中首次热冲击对裂隙砂岩力学性能的损伤最为严重,且当热冲击次数超过4次时,热冲击对裂隙砂岩力学特性的损伤显著减缓。此外,裂隙砂岩单轴抗压强度和弹性模量与纵波波速具有很好的指数函数关系。最后,在COMSOL Multiphysics中模拟了砂岩试样热冲击过程,并讨论了对流换热系数和预制裂纹对砂岩内部温度场和应力场的影响,揭示了热冲击作用下砂岩产生热裂纹的机制。The stimulation of thermal reservoir in sandstone and long-term stability evaluation are of great significance to the development of geothermal energy.The mechanical properties of fractured sandstone under 0-8 thermal shocks are studied in this paper.The experimental results show that the P-wave velocity,uniaxial compressive strength and elastic modulus of the fractured sandstone all decrease gradually with the increase of the number of thermal shocks under two types of cooling methods.Compared with cooling method in water,the natural cooling method in air has less damage to mechanical properties of fractured sandstone.The uniaxial compressive strength and elastic modulus of fractured sandstone show a good exponential function relationship with the number of thermal shocks.Both the P-wave velocity and the elastic modulus can be used to describe the damage of the fractured sandstone with the number of thermal shocks.The first thermal shock weakens the mechanical properties of fractured sandstone most severely,and the deterioration effect of mechanical properties is significantly slowed down when the number of thermal shocks exceeds 4.In addition,the uniaxial compressive strength and elastic modulus of fractured sandstone also have a good exponential function relationship with the P-wave velocity.Finally,the thermal shock process of sandstone samples is simulated in COMSOL Multiphysics,and the effects of heat transfer coefficient and prefabricated cracks on the internal temperature field and stress field of sandstone are discussed,revealing the mechanism of thermal cracking in sandstone under thermal shock effect.

关 键 词：砂岩 预制裂纹 循环热冲击 损伤演化 热破裂 

分 类 号：TU452[建筑科学—岩土工程]