(1. State Key Laboratory of Water Resources and Hydropower Engineering Science，Wuhan University，Wuhan，Hubei 430072，
China；2. Key Laboratory of Rock Mechanics in Hydraulic Structural Engineering，Ministry of Education，
Wuhan University，Wuhan，Hubei 430072，China)
Abstract：In this study，the alterations in the microstructures of three types of rocks (i.e. sandstone，granite and marble) were observed with the polarized light microscopy after thermal treatment at different temperatures. The variations in the physical-mechanical properties(including the longitudinal wave velocity，porosity，Young?s modulus，peak stress and the corresponding strain) of three types of rocks with the thermal treatment from room temperature to 800 ℃ were analyzed and compared and were correlated to the microstructural variations. The strong ductile behavior of the thermally cracked rocks was interpreted with a micromechanical model by taking into account the normal stiffness reduction of micro-cracks. A notable change in the carbonate cementation was observed in thermally cracked sandstone，in which the thermally induced cracking was not developed across the mineral particles. Both transgranular and intergranular cracking developed in thermally cracked granite with a maximum opening of 100 μm at 800 ℃，which was one order of magnitude larger than that at 400 ℃. The cracks in thermally treated marble were mainly intergranular，with the maximum width of about 20 μm at 600 ℃. Different from granite and marble，a dramatic decrease of elastic modulus occurred in thermally cracked sandstone when the treatment temperature was over 500 ℃，which was mainly ascribed to the phase transition of quartz. It was found that the physical-mechanical properties of the thermally cracked rocks depended much on the diagenetic processes，mineral compositions and cracking patterns. Moreover，the numerical simulation results are in good agreement with the experimental data，showing that the mechanical behaviors of the thermally cracked rocks are closely related to the density and stiffness of the thermally induced cracks.
[1] 苏承东，郭文兵，李小双. 粗砂岩高温作用后力学效应的试验研究[J]. 岩石力学与工程学报，2008，27(6)：1 162–1 170.(SU Chengdong，GUO Wenbing，LI Xiaoshuang. Experimental research on mechanical properties of coarse sandstone after high temperatures[J] Chinese Journal of Rock Mechanics and Engineering，2008，27(6)：1 162– 1 170.(in Chinese))
[2] 苏海健，靖洪文，赵洪辉，等. 高温处理后红砂岩抗拉强度及其尺寸效应研究[J]. 岩石力学与工程学报，2015，34(增1)：2 879–2 887. (SU Haijian，JING Hongwen，ZHAO Honghui，et al. Study on tensile strength and size effect of red sandstone after high temperature treatment[J] Chinese Journal of Rock Mechanics and Engineering，2015，34(Supp.1)：2 879–2 887.(in Chinese))
[3] 尹光志，李小双，赵洪宝. 高温后粗砂岩常规三轴压缩条件下力学特性试验研究[J]. 岩石力学与工程学报，2009，28(3)：598–604. (YIN Guangzhi，LI Xiaoshuang，ZHAO Hongbao. Experimental investigation on mechanical properties of coarse sandstone after high temperature under conventional triaxial compression[J] Chinese Journal of Rock Mechanics and Engineering，2009，28(3)：598–604. (in Chinese))
[4] 苏海健，靖洪文，赵洪辉. 高温后砂岩单轴压缩加载速率效应的试验研究[J]. 岩土工程学报，2014，36(6)：1 064–1 071.(SU Haijian，JING Hongwen，ZHAO Honghui. Experimental investigation on loading rate effect of sandstone after high temperature under uniaxial compression[J] Chinese Journal of Geotechnical Engineering，2014，36(6)：1 064–1 071.(in Chinese))
[5] 尹土兵，李夕兵，殷志强，等. 高温后砂岩静、动态力学特性研究与比较[J]. 岩石力学与工程学报，2012，31(2)：273–279.(YIN Tubing，LI Xibing，YIN Zhiqiang. Study and comparison of mechanical properties of sandstone under static and dynamic loadings after high temperature[J]. Chinese Journal of Rock Mechanics and Engineering，2012，31(2)：273–279.(in Chinese))
[6] 李建林，陈 星，党 莉，等. 高温后砂岩三轴卸荷试验研究[J]. 岩石力学与工程学报，2011，30(8)：1 587–1 595.(LI Jianlin，CHEN Xing，DANG Li，et al. Triaxial unloading test of sandstone after high temperature[J]. Chinese Journal of Rock Mechanics and Engineering，2011，30(8)：1 587–1 595. (in Chinese))
[7] 王 鹏，许金余，刘 石，等. 热损伤砂岩力学与超声时频特性研究[J]. 岩石力学与工程学报，2014，33(9)：1 897–1 904.(WANG Peng，XU Jinyu，LIU Shi，et al. Mechanical properties and ultrasonic time-frequency characteristics of thermally damaged sandstone[J] Chinese Journal of Rock Mechanics and Engineering，2014，33(9)： 1 897–1 904.(in Chinese))
[8] 尤明庆，苏承东，李小双. 损伤岩石试样的力学特性与纵波速度关系研究[J]. 岩石力学与工程学报，2008，27(3)：458–467.(YOU Mingqing，SU Chengdong，LI Xiaoshuang. Study on relation between mechanical properties and longitudinal wave velocities for damaged rock samples[J]. Chinese Journal of Rock Mechanics and Engineering，2008，27(3)：458–467.(in Chinese))
[9] 苏承东，韦四江，杨玉顺，等. 高温后粗砂岩常规三轴压缩变形与强度特征分析[J]. 岩石力学与工程学报，2015，34(增1)：2 792– 2 800.(SU Chengdong，WEI Sijiang，YANG Yushun，et al. Analysis of strength and conventional triaxial compression deformation characters of coarse sandstone after high temperature[J]. Chinese Journal of Rock Mechanics and Engineering，2015，34(Supp.1)：2 792–2 800.(in Chinese))
[10] 吴 刚，王德咏，翟松韬. 单轴压缩下高温后砂岩的声发射特征[J]. 岩土力学，2012，33(11)：3 237–3 242.(WU Gang，WANG Deyong，ZHAI Songtao. Acoustic emission characteristics of sandstone after high temperature under uniaxial compression[J]. Rock and Soil Mechanics，2012，33(11)：3 237–3 242.(in Chinese))
[11] WU G，WANG Y，SWIFT G，et al. Laboratory investigation of the effects of temperature on the mechanical properties of sandstone[J]. Geotechnical and Geological Engineering，2013，31(2)：809–816.
[12] HOMAND-ETIENNE F，HOUPERT R. Thermally induced micro cracking in granites：characterization and analysis[J]. International Journal of Rock Mechanics and Mining Sciences and Geomechanics Abstracts，1989，26(2)：125–134.
[13] WANG X Q，SCHUBNEL A，FORTIN J，et al. Physical properties and brittle strength of thermally cracked granite under confinement[J]. Journal of Geophysical Research：Solid Earth，2013，118(12)：6 099– 6 112.
[14] CHEN Y L，NI J，SHAO W，et al. Experimental study on the influence of temperature on the mechanical properties of granite under uniaxial compression and fatigue loading[J]. International Journal of Rock Mechanics and Mining Sciences，2012，56(8)：62–66.
[15] CHAKI S，TAKARLI M，AGBODJAN W P. Influence of thermal damage on physical properties of a granite rock：porosity，permeability and ultrasonic wave evolutions[J]. Construction and Building Materials，2008，22(7)：1 456–1 461.
[16] 杜守继，刘 华，职洪涛，等. 高温后花岗岩力学性能的试验研究[J]. 岩石力学与工程学报，2004，23(14)：2 359–2 364.(DU Shouji，LIU Hua，ZHI Hongtao，et al. Testing study on mechanical properties of post-high-temperature granite[J]. Chinese Journal of Rock Mechanics and Engineering，2004，23(14)：2 359–2 364.(in Chinese))
[17] 杜守继，马 明，陈浩华，等. 花岗岩经历不同高温后纵波波速分析[J]. 岩石力学与工程学报，2003，22(11)：1 803–1 806.(DU Shouji，MA Ming，CHEN Haohua，et al. Testing study on longitudinal wave characteristics of granite after high temperature[J] Chinese Journal of Rock Mechanics and Engineering，2003，22(11)：1 803–1 806.(in Chinese))
[18] 徐小丽，高 峰，沈晓明，等. 高温后花岗岩力学性质及微孔隙结构特征研究[J]. 岩土力学，2010，31(6)：1 752–1 758.(XU Xiaoli，GAO Feng，SHEN Xiaoming，et al. Research on mechanical characteristics and micropore structure of granite under high- temperature[J]. Rock and Soil Mechanics，2010，31(6)：1 752–1 758. (in Chinese))
[19] 徐小丽，高 峰，张志镇. 高温作用后花岗岩三轴压缩试验研究[J]. 岩土力学，2014，35(11)：3 177–3 183.(XU Xiaoli，GAO Feng，ZHANG Zhizhen. Research on triaxial compression test of granite after high temperatures[J]. Rock and Soil Mechanics，2014，35(11)：3 177–3 183.(in Chinese))
[20] 蔡燕燕，罗承浩，俞 缙，等. 热损伤花岗岩三轴卸围压力学特性试验研究[J]. 岩土工程学报，2015，37(7)：1 173–1 180.(CAI Yanyan，LUO Chenghao，YU Jin，et al. Experimental study on mechanical properties of thermal-damage granite rock under triaxial unloading confining pressure[J]. Chinese Journal of Geotechnical Engineering，2015，37(7)：1 173–1 180.(in Chinese))
[21] 郭清露，荣 冠，姚孟迪，等. 大理岩热损伤声发射力学特性试验研究[J]. 岩石力学与工程学报，2015，34(12)：2 388–2 400.(GUO Qinglu，RONG Guan，YAO Mengdi，et al. Experimental study on acoustic emission behaviors and mechanical properties of thermal damaged marbles[J]. Chinese Journal of Rock Mechanics and Engineering，2015，34(12)：2 388–2 400.(in Chinese))
[22] LIU S，XU J. Analysis on damage mechanical characteristics of marble exposed to high temperature[J]. International Journal of Damage Mechanics，2015，24(8)：1 180–1 193.
[23] 许金余，刘 石. 加载速率对高温后大理岩动态力学性能的影响研究[J]. 岩土工程学报，2013，35(5)：879–883.(XU Jinyu，LIU Shi. Effect of impact velocity on dynamic mechanical behaviors of marble after high temperatures[J]. Chinese Journal of Geotechnical Engineering，2013，35(5)：879–883.(in Chinese))
[24] 刘 石，许金余，支乐鹏，等. 高温后大理岩的冲击力学特性试验研究[J]. 岩石力学与工程学报，2013，32(2)：273–280.(LIU Shi，XU Jinyu，ZHI Lepeng，et al. Experimental research on mechanical behaviors of marble after high temperatures subjected to impact loading[J]. Chinese Journal of Rock Mechanics and Engineering，2013，32(2)：273–280.(in Chinese))
[25] 秦 严，田 红，徐能雄，等. 高温后闪长岩部分物理性质实验研究[J]. 岩土工程学报，2015，37(7)：1 226–1 231.(QIN Yan，TIAN Hong，XU Nengxiong，et al. Experimental study on partial physical properties of post-high-temperature diorite[J] Chinese Journal of Geotechnical Engineering，2015，37(7)：1 226–1 231.(in Chinese))
[26] FREDRICH J T，WONG T. Micromechanics of thermally induced cracking in three crustal rocks[J]. Journal of Geophysical Research：Solid Earth，1986，91(B12)：12 743–12 764.
[27] FAORO I，VINCIGUERRA S，MARONE C，et al. Linking permeability to crack density evolution in thermally stressed rocks under cyclic loading[J]. Geophysical Research Letters，2013，40(11)：2 590–2 595.
[28] 朱合华，闫治国，邓 涛，等. 3种岩石高温后力学性质的试验研究[J]. 岩石力学与工程学报，2006，25(10)：1 945–1 950.(ZHU Hehua，YAN Zhiguo，DENG Tao，et al. Testing study on mechanical properties of tuff，granite and breccia after high temperatures[J] Chinese Journal of Rock Mechanics and Engineering，2006，25(10)：1 945–1 950.(in Chinese))
[29] 闫治国，朱合华，邓 涛，等. 三种岩石高温后纵波波速特性的试验研究[J]. 岩土工程学报，2006，28(11)：2 010–2 014.(Experimental study on longitudinal wave characteristics of tuff， granite and breccia after high temperature[J]. Chinese Journal of Geotechnical Engineering，2006，28(11)：2 010–2 014.(in Chinese))
[30] CHEN Y，LI D，JIANG Q，et al. Micromechanical analysis of anisotropic damage and its influence on effective thermal conductivity in brittle rocks[J]. International Journal of Rock Mechanics and Mining Sciences，2012，50(2)：102–116.
[31] 朱其志，胡大伟，周 辉，等. 基于均匀化理论的岩石细观力学损伤模型及其应用研究[J]. 岩石力学与工程学报，2008，27(2)：266–272.(ZHU Qizhi，HU Dawei，ZHOU Hui，et al. Research on homogenization-based mesomechanical damage model and its application[J]. Chinese Journal of Rock Mechanics and Engineering，2008，27(2)：266–272.(in Chinese))
[32] 陈益峰，李典庆，荣 冠，等. 脆性岩石损伤与热传导特性的细观力学模型[J]. 岩石力学与工程学报，2011，30(10)：1 959–1 969. (CHEN Yifeng，LI Dianqing，RONG Guan，et al. A micromechanical model for damage and thermal conductivity of brittle rocks[J]. Chinese Journal of Rock Mechanics and Engineering，2011，30(10)：1 959–1 969.(in Chinese))
[33] 陈益峰，胡 冉，周创兵，等. 热–水–力耦合作用下结晶岩渗透特性演化模型[J]. 岩石力学与工程学报，2013，32(11)：2 185–2 195. (CHEN Yifeng，HU Ran，ZHOU Chuangbing，et al. A permeability evolution model for crystalline rocks subjected to coupled thermo- hydro-mechanical loading[J]. Chinese Journal of Rock Mechanics and Engineering，2013，32(11)：2 185–2 195.(in Chinese))
[34] ZHU Q Z，SHAO J F. A refined micromechanical damage–friction model with strength prediction for rock-like materials under compression[J]. International Journal of Solids and Structures，2015，60(8)：75–83.
[35] ISRM. The complete ISRM suggested methods for rock characterization，testing and monitoring：1974–2006[M]. International Society for Rock Mechanics，Commission on Testing Methods，2007.
[36] MARTIN C D，CHANDLER N A. The progressive fracture of Lac du Bonnet granite[J]. International Journal of Rock Mechanics and Mining Sciences and Geomechanics Abstracts，1994，31(6)：643–659.
2017, Vol. 36 
