寒区路堑边坡裂隙岩体长期受到车辆振动等周期载荷的作用，地质灾害频发，严重威胁道路的安全运营，周期荷载作用下冻融裂隙岩石的损伤机理急需研究。本文以单裂隙大理岩为研究对象，采用室内试验及理论分析相结合的方法开展研究。主要结论是：

（1）完成了常温下单裂隙大理岩三轴压缩及周期荷载试验，同步声发射试验。试验结果表明：单轴压缩作用下，裂隙倾角为60°的单裂隙大理岩强度最高，30°最低；随着围压的增大，破坏模式由局部剪切破坏向整体剪切破坏过渡；声发射事件的集中区与岩样宏观裂纹出现区基本可以对应。周期荷载作用下，声发射累计振铃计数曲线呈“缓-急-缓-急”的变化规律，在周期荷载加载初期及岩样破坏阶段声发射事件最为活跃。

（2）完成了冻融循环试验、单裂隙大理岩冻融后三轴压缩及声发射试验，试验结果表明：冻融后单裂隙大理岩质量的损伤程度与冻融次数呈正相关，得到岩样质量损失率。随裂隙倾角增大，抗压强度先减后增；随着围压升高，强度呈现增大趋势，破坏时以单一剪切裂纹破坏为主；随冻融次数的增多，抗压强度衰减趋势越来越明显，破坏模式由局部剪切破坏过渡到整体剪切破坏。冻融后的岩样声发射累计振铃计数变化曲线大致可以分为沉寂期、活跃期以及爆发期，在预制裂隙端部产生明显的声发射信号集中区。

（3）完成了冻融后不同裂隙倾角单裂隙大理岩周期荷载试验，同步进行声发射试验及高速摄影机录像。试验结果表明：冻融后岩样周期荷载次数对裂隙倾角的变化不敏感；幅值对岩样疲劳损伤影响显著，应力比幅值0.5时，周期荷载次数约为应力比0.6时的3~4倍，应力比0.4时，约为7~8倍；随着围压的增加，破坏点处的应变及周期荷载循环次数皆随之增加。声发射信号集中于周期荷载加载初期及岩样破坏阶段。

（4）完成了冻融前后、三轴压缩及周期荷载试验后的单裂隙大理岩核磁共振细观试验。试验结果表明：单裂隙大理岩孔径分布主要在10~1000范围内；随着冻融循环次数的增加，T₂谱曲线分布整体向右移动，峰总面积依次增大，微孔占比减少，小孔及中孔增多，大孔开始出现。周期荷载作用下峰谱面积变化更为显著，内部微小裂纹的贯通连接现象更加显著，裂纹尺寸分布更加复杂。周期荷载振幅越小，岩样峰总面积变化率越大，中孔及大孔占比增加。

（5）研究结果表明：宏观预制裂隙的存在深刻影响了大理岩的破裂机理，受载后预制裂隙端部易出现应力集中区，产生翼裂纹，出现张拉破坏特性。受冻融循环影响，大理岩的宏观破裂机理表现为：裂隙内水的反复冻胀融缩作用产生微裂纹，在受载后内部先破坏；细观破裂机理表现为岩样孔隙率增大，裂纹更易相互贯通。受周期荷载作用影响，大理岩宏观破裂机理表现为：应力循环造成微裂纹反复的发生张开与闭合，微小裂纹得到了充分的发展，破坏时表现为局部剪切破坏，出现岩块掉落；细观机理是微小裂纹贯通连接现象更显著，裂纹尺寸更复杂。周期荷载振幅越小，岩样破坏越充分，内部微小裂纹的贯通连接现象越显著。

（6）根据试验结果，单裂隙大理岩在疲劳试验过程中的不可逆轴向变形与最大轴向应变可划分为初始阶段、等速阶段和加速阶段，与蠕变曲线中的瞬时蠕变、稳态蠕变和加速蠕变三个阶段是相似的。故用蠕变模型模拟周期荷载试验变形三阶段，用循环次数与频率换算代替蠕变时间，基于传统的西原蠕变模型，把线性黏性元件替换为非线性黏性元件，引入冻融损伤变量后，得到周期荷载下冻融单裂隙大理岩三轴压缩疲劳本构模型，理论模型与试验结果基本吻合。

The fractured rock mass of the cutting slope in the cold region has been subjected to periodic loads such as vehicle vibration for a long time, and disasters occur frequently, which seriously threatens the safe operation of the road. The damage mechanism of frozen-thawed fractured rock under periodic load needs to be studied urgently. In this paper, the single fracture marble is taken as the research object, and the research work is carried out by combining laboratory test and theoretical analysis. The main conclusions are:

Firstly, the triaxial compression and periodic load test of single fracture marble at room temperature and synchronous acoustic emission test were completed. The experimental results show that: under uniaxial compression, the strength of single fracture marble with fracture dip angle of 60° is the highest and that of 30° is the lowest. With the increase of confining pressure, the failure mode transits from local shear failure to overall shear failure. The concentrated area of acoustic emission events can basically correspond to the macroscopic crack area of rock samples. Under the action of periodic load, the cumulative ringing count curve of acoustic emission shows the change rule of ' slow-quick-slow-quick ', and the acoustic emission events are the most active in the initial stage of periodic load loading and rock failure stage.

Secondly, the freeze-thaw cycle test, triaxial compression and acoustic emission test of single fracture marble after freeze-thaw were completed. The experimental results show that: the damage degree of single fracture marble mass after freeze-thaw is positively correlated with the number of freeze-thaw cycles, and the mass loss rate of rock samples is obtained. With the increase of fracture dip angle, the compressive strength decreases first and then increases. With the increase of confining pressure, the strength increases, and the failure is dominated by single shear crack failure. With the increase of freeze-thaw times, the attenuation trend of compressive strength is more and more obvious, and the failure mode transitions from local shear failure to overall shear failure. The cumulative ringing count change curve of acoustic emission of rock samples after freezing and thawing can be roughly divided into quiet period, active period and outbreak period, and obvious acoustic emission signal concentration area is generated at the end of prefabricated cracks.

Then, the periodic load test of marble with different fracture dip angles after freeze-thaw was completed, and the acoustic emission test and high-speed camera video were carried out simultaneously. The experimental results show that: the number of periodic loads of rock samples after freezing and thawing is not sensitive to the change of fracture dip angle. The amplitude has a significant effect on the fatigue damage of rock samples. When the stress ratio amplitude is 0.5, the number of periodic loads is about 3~4 times that of the stress ratio of 0.6, and about 7~8 times that of the stress ratio of 0.4. With the increase of confining pressure, the strain at the failure point and the number of cyclic loading cycles increases. The acoustic emission signals are concentrated in the initial stage of cyclic loading and the failure stage of rock samples.

After that, the nuclear magnetic resonance (NMR) mesoscopic test of single-crack marble before and after freeze-thaw, monotonic loading and periodic load test was completed.  The experimental results show that: the pore size distribution of single fracture marble is mainly in the range of 10~1000. With the increase of freeze-thaw cycles, the distribution of T2 spectrum curve moved to the right as a whole, the total peak area increased in turn, the proportion of micropores decreased, the number of small and medium pores increased, and the large pores began to appear. Under the action of periodic load, the peak spectrum area changes more significantly, the connection phenomenon of internal micro-cracks is more significant, and the crack size gradation is more complicated. The smaller the amplitude of the periodic load is, the greater the change rate of the total peak area of the rock sample is, and the proportion of mesopores and macropores increases.

The results show that the existence of macroscopic prefabricated cracks has a profound impact on the fracture mechanism of marble. After loading, the stress concentration zone is prone to occur at the end of prefabricated cracks, resulting in wing cracks and tensile failure characteristics. Under the influence of freeze-thaw cycles, the macroscopic fracture mechanism of marble is as follows: the repeated frost heaving and thawing shrinkage of water in the fracture produces micro cracks, and the internal damage occurs first under pressure; the microscopic fracture mechanism is that the porosity of the rock sample increases, and the cracks are more easily interconnected. Under the influence of periodic load, the macroscopic fracture mechanism of marble is as follows: the stress cycle causes the micro-cracks to open and close repeatedly, and the micro-cracks have been fully developed, and the failure is manifested as local shear failure, and the rock block falls; the microscopic mechanism is that the phenomenon of micro-crack connection is more significant and the crack size is more complex. The smaller the amplitude of the periodic load is, the more sufficient the rock sample is destroyed, and the more obvious the connection of the internal micro-cracks is.

Finally, according to the test results, the irreversible axial deformation and maximum axial strain of single-crack marble during fatigue test can be divided into initial stage, constant speed stage and acceleration stage, which is similar to the three stages of instantaneous creep, steady creep and accelerated creep in creep curve. Therefore, the creep model is used to simulate the three stages of deformation in the periodic load test. The creep time is replaced by the conversion of the number of cycles and the frequency. Based on the traditional Nishihara creep model, the linear viscous element is replaced by the nonlinear viscous element. After introducing the freeze-thaw damage variable, the triaxial compression fatigue constitutive model of frozen-thawed single-fracture marble under periodic load is obtained. The theoretical model is basically consistent with the experimental results.

[1]彭建兵, 崔鹏, 庄建琦. 川藏铁路对工程地质提出的挑战[J]. 岩石力学与工程学报, 2020, 39(12): 2377-2389.

[2]李洪梁, 高波, 张佳佳, 等. 内外动力地质作用耦合的崩塌形成机理研究:以藏东昌都地区上三叠统石灰石矿山采场崩塌为例[J]. 地质力学学报, 2022, 28(06): 995-1011.

[3]舒佳军, 邓正定, 黄晶柱, 等. 冻融循环作用下危岩体滑移破坏数值优化分析[J/OL]. 工程科学与技术.

[4]郭长宝, 张永双, 蒋良文, 等. 川藏铁路沿线及邻区环境工程地质问题概论[J]. 现代地质, 2017, 31(05): 877-889.

[5]WANG Y F, CHENG Q G, LIN Q W, et al. Insights into the kinematics and dynamics of the Luanshibao rock avalanche (Tibetan Plateau, China) based on its complex surface landforms[J]. Geomorphology, 2018, 317:170–183.

[6]乔国文, 王运生, 储飞, 等. 冻融风化边坡岩体破坏机理研究[J]. 工程地质学报, 2015, 23(03): 469-476.

[7]杨更社, 申艳军, 贾海梁, 等. 冻融环境下岩体损伤力学特性多尺度研究及进展[J]. 岩石力学与工程学报, 2018, 37(03): 545-563.

[8]陈宇龙, 张科, 孙欢. 冻融循环作用下岩石表面裂纹扩展过程细观研究[J]. 土木工程学报, 2019, 52(S1): 1-7.

[9]张慧梅, 杨更社. 冻融岩石损伤劣化及力学特性试验研究[J]. 煤炭学报, 2013, 38(10): 1756-1762.

[10]贺晶晶, 师俊平. 冻融后不同含水状态砂岩的剪切破坏特性[J]. 岩石力学与工程学报, 2018, 37(06): 1350-1358.

[11]王永岩, 柳雪庆, 苏传奇, 等. 冻融循环对不同孔隙率页岩相似材料影响的试验研究[J]. 冰川冻土, 2018, 40(01): 102-109.

[12]龙士国, 徐继同, 李日进, 等. 冻融作用下断续节理岩体损伤与力学特性研究[J/OL]. 防灾减灾工程学报.

[13]杨鸿锐, 刘平, 孙博, 等. 冻融循环对麦积山石窟砂砾岩微观结构损伤机制研究[J]. 岩石力学与工程学报, 2021, 40(03): 545-555.

[14]刘德俊, 浦海, 沙子恒, 等. 冻融循环条件下砂岩动态拉伸力学特性试验研究[J]. 煤炭科学技术, 2022, 50(08): 60-67.

[15]Yahaghi J. Experimental and numerical studies on the deterioration and failure process of Tasmanian sandstone subject to freeze-thaw cycles[D]. University of Tasmania, 2022.

[16]Ince I, Fener M. A prediction model for uniaxial compressive strength of deteriorated pyroclastic rocks due to freeze-thaw cycle[J]. Journal of African Earth Sciences, 2016, 120: 134-140.

[17]Han T, Shi J, Cao X. Fracturing and damage to sandstone under coupling effects of chemical corrosion and freeze-thaw cycles[J]. Rock Mechanics and Rock Engineering, 2016, 49(11): 4245-4255.

[18]Ghobadi M H, Babazadeh R. Experimental studies on the effects of cyclic freezing-thawing, salt crystallization, and thermal shock on the physical and mechanical characteristics of selected sandstones[J]. Rock Mechanics and Rock Engineering, 2015, 48(3): 1001-1016.

[19]Julian B. Murton, Oliver Kuras, Michael Krautblatter, Tim Cane, Dominique Tschofen, Sebastian Uhlemann, Sandra Schober, Phil Watson. Monitoring rock freezing and thawing by novel geoelectrical and acoustic techniques[J]. Journal of Geophysical Research: Earth Surface, 2016, 121(12): 2309-2332.

[20]Mutluturk M, Altindag R, Turk G. A decay function model for the integrity loss of rock when subjected to recurrent cycles of freezing-thawing and heating-cooling[J]. International Journal of Rock Mechanics and Mining Sciences, 2004, 41(2): 237-244.

[21]Martins L, Vasconcelos G, Lourenco P B, et al. Influence of the freeze-thaw cycles on the physical and mechanical properties of granites[J]. Journal of Materials in Civil Engineering, 2016, 28(5).

[22]Luo X, Jiang N, Zuo C, et al. Damage characteristics of altered and unaltered diabases subjected to extremely cold freeze-thaw cycles[J]. Rock Mechanics and Rock Engineering, 2014, 47:1997-2004.

[23]Brondani C, Faccin C, Specht L P, et al. Evaluation of Moisture Susceptibility of Asphalt Mixtures: Influence of Aggregates, Visual Analysis, and Mechanical Tests[J]. Journal of Materials in Civil Engineering, 2023, 35(2): 04022433.

[24]Chen Y, Lin H. Deterioration laws of Hoek-Brown parameters in freeze-thaw multi-fractured rock mass[J]. Theoretical and Applied Fracture Mechanics, 2023, 123: 103716.

[25]Wen H, Yang R, Lu M, et al. Experimental comparisons of different cryogenic fracturing methods on coals[J]. Journal of Petroleum Science and Engineering, 2023, 220: 111250.

[26]Yu Q, Lei P, Dai Z, et al. Damage Characteristics of Limestone under Freeze-Thaw Cycle for Tunnels in Seasonal Frozen Areas[J]. Iranian Journal of Science and Technology, Transactions of Civil Engineering, 2022: 1-9.

[27]Fan L, Fan Y, Xi Y, et al. Spatially distributed damage in sandstone under stress-freeze-thaw coupling conditions[J]. Journal of Rock Mechanics and Geotechnical Engineering, 2022.

[28]葛修润, 蒋宇, 卢允德, 等. 周期荷载作用下岩石疲劳变形特性试验研究[J]. 岩石力学与工程学报, 2003(10): 1581-1585.

[29]蒋宇, 葛修润, 任建喜. 岩石疲劳破坏过程中的变形规律及声发射特性[J]. 岩石力学与工程学报, 2004(11): 1810-1814.

[30]尹敬涵,崔臻,盛谦,等.循环荷载作用下岩石劈裂结构面剪切力学特性演化与影响因素研究[J].岩土力学,2023,44(01):109-118.

[31]马林建, 刘新宇, 许宏发, 等. 循环荷载作用下盐岩三轴变形和强度特性试验研究[J]. 岩石力学与工程学报, 2013, 32(04): 849-856.

[32]魏元龙, 杨春和, 郭印同, 等. 单轴循环荷载下含天然裂隙脆性页岩变形及破裂特征试验研究[J]. 岩土力学, 2015, 36(06): 1649-1658.

[33]张琰, 李江腾. 单调及循环加载下大理岩断裂特性研究[J]. 岩石力学与工程学报, 2019, 38(S2): 3313-3320.

[34]郜欣, 徐颖, 李成杰, 等. 不同应力比的循环荷载下砂岩变形损伤特性研究[J]. 中国安全生产科学技术, 2021, 17(11): 60-64.

[35]苗胜军, 王辉, 黄正均, 等. 不同循环上限荷载下泥质石英粉砂岩力学特性试验研究[J]. 工程力学, 2021, 38(07): 75-85.

[36]张培森, 许大强, 张睿, 等. 不同围压及循环载荷下砂岩的渗流、力学特性试验研究[J]. 岩石力学与工程学报, 2022, 41(12): 2432-2450.

[37]刘建锋, 翟俨伟, 裴建良, 等. 不同频率循环荷载下大理岩动力学特性试验研究[J]. 河南理工大学学报(自然科学版), 2014, 33(04): 432-436.

[38]李昊禹, 孟陆波, 李天斌, 等. 不同含水状态砂岩单轴循环荷载的微观损伤机制研究[J/OL]. 中国测试.

[39]Yang D J, Hu J H, Wen G P, et al. Analysis of fracture deformation field and energy evolution of granite after high confining pressure cyclic load pre-damage[J]. Royal Society Open Science, 2021, 8(6).

[40]Xiao J Q, Ding D X, Jiang F L, et al. Fatigue damage variable and evolution of rock subjected to cyclic loading[J]. International Journal of Rock Mechanics & Mining Sciences, 2010, 47(3):461-468.

[41]Xu Y, Ren F Y, Ahmed Z, et al. Mechanical Characteristics and Damage Evolution Law of Sandstone with Prefabricated Cracks Under Cyclic Loading[J]. Arabian Journal for Science and Engineering, 2021, 46(11).

[42]Vaneghi R G, Ferdosi B, Okoth A D, et al. Strength degradation of sandstone and granodiorite under uniaxial cyclic loading[J]. Journal of Rock Mechanics and Geotechnical Engineering, 2018, 10(01): 117-126.

[43]Zhou X P, Jiang D C, Zhao Z. Digital Evaluation of Micro-Pore Water Effects on Mechanical and Damage Characteristics of Sandstone Subjected to Uniaxial, Cyclic Loading-Unloading Compression by 3D Reconstruction Technique[J]. Rock Mechanics and Rock Engineering, 2021, 55(1): 147-167.

[44]Wang Y, Gao S H, Li C H, et al. Energy dissipation and damage evolution for dynamic fracture of marble subjected to freeze-thaw and multiple level compressive fatigue loading[J]. International Journal of Fatigue, 2020, 142: 105927.

[45]Song Z, Wang Y, Konietzky H, et al. Mechanical behavior of marble exposed to freeze-thaw-fatigue loading[J]. International Journal of Rock Mechanics and Mining Sciences, 2021, 138: 104648.

[46]王宇, 高少华, 孟华君, 等. 不同频率增幅疲劳荷载下双裂隙花岗岩破裂演化声发射特性与裂纹形态研究[J]. 岩石力学与工程学报, 2021, 40(10): 1976-1989.

[47]王天佐, 王春力, 薛飞, 等. 不同循环加卸载路径下红砂岩声发射与应变场演化规律研究[J]. 岩石力学与工程学报, 2022, 41(S1): 2881-2891.

[48]王晓军, 张河, 陈青林, 等. 不同岩爆倾向性灰岩加载声发射特征及损伤模型[J]. 岩石力学与工程学报, 2022, 41(07): 1373-1383.

[49]宋彦琦, 马宏发, 刘济琛, 等. 冻融灰岩单轴声发射损伤特性试验研究[J]. 岩石力学与工程学报, 2022, 41(S1): 2603-2614.

[50]董陇军, 张义涵, 孙道元, 等. 花岗岩破裂的声发射阶段特征及裂纹不稳定扩展状态识别[J]. 岩石力学与工程学报, 2022, 41(01): 120-131.

[51]张志博, 李树杰, 王恩元, 等. 基于声发射事件时空维度聚类分析的煤体损伤演化特征研究[J]. 岩石力学与工程学报, 2020, 39(S2): 3338-3347.

[52]傅帅旸, 李海波, 李晓锋. 基于DIC方法与声发射的花岗岩断裂过程区范围研究[J]. 岩石力学与工程学报, 2022, 41(12): 2497-2508.

[53]Ding Z, Feng X, Wang E, et al. Acoustic emission response and evolution of precracked coal in the meta-instability stage under graded loading[J]. Engineering Geology, 2023, 312: 106930.

[54]Dong L, Zhang Y, Bi S, et al. Uncertainty investigation for the classification of rock micro-fracture types using acoustic emission parameters[J]. International Journal of Rock Mechanics and Mining Sciences, 2023, 162: 105292.

[55]Wei H, Zhang H, Li J, et al. Effect of loading rate on failure characteristics of asphalt mixtures using acoustic emission technique[J]. Construction and Building Materials, 2023, 364: 129835.

[56]Meng Q, Zhang M, Han L, et al. Acoustic Emission Characteristics of Red Sandstone Specimens Under Uniaxial Cyclic Loading and Unloading Compression[J]. Rock Mechanics & Rock Engineering, 2018, 51(4):1-20.

[57]Liu T Y, Zhang C Y, Cao P, et al. Freeze-thaw damage evolution of fractured rock mass using nuclear magnetic resonance technology [J]. Cold Regions Science and Technology,2020,170(C).

[58]陈国庆, 简大华, 陈宇航, 等. 不同含水率冻融后红砂岩剪切蠕变特性[J]. 岩土工程学报, 2021, 43(04): 661-669.

[59]刘波, 孙颜顶, 袁艺峰, 等. 不同含水率冻结砂岩强度特性及强度强化机制[J]. 中国矿业大学学报, 2020, 49(06): 1085-1093+1127.

[60]姜德义, 张水林, 陈结, 等. 砂岩循环冻融损伤的低场核磁共振与声发射概率密度研究[J]. 岩土力学, 2019, 40(02): 436-444.

[61]李杰林, 周科平, 柯波. 冻融后花岗岩孔隙发育特征与单轴抗压强度的关联分析[J]. 煤炭学报, 2015, 40(08): 1783-1789.

[62]李杰林, 朱龙胤, 周科平, 等. 冻融作用下砂岩孔隙结构损伤特征研究[J]. 岩土力学, 2019, 40(09): 3524-3532.

[63]浦少云, 黄质宏, 饶军应, 等. 低动应力下岩石分数阶Burgers本构模型[J]. 长江科学院院报, 2018, 35(02): 109-115.

[64]吕思清, 朱杰兵, 汪斌, 等. 冻融荷载耦合作用下含开口裂隙砂岩宏细观损伤模型研究[J/OL]. 岩石力学与工程学报.

[65]万镇昂, 马昆林, 龙广成, 等. 基于Weibull分布和残余应变的SCC疲劳损伤本构模型[J]. 材料导报, 2019, 33(04): 634-638.

[66]彭述权, 王培宇, 樊玲, 等. 节理岩体弹塑黏性疲劳本构模型研究[J]. 岩土力学, 2021, 42(02): 379-389.

[67]刘汉卿, 浦少云, 刘西金, 等. 周期荷载下岩石分数阶黏弹塑性本构模型研究[J]. 长江科学院院报, 2018, 35(09): 127-132+138.

[68]唐欣, 俞缙, 林立华, 等. 岩石疲劳应力等效化及非线性疲劳变形本构模型[J]. 岩土工程学报, 2021, 43(01): 102-111.

[69]张平阳, 夏才初, 周舒威, 等. 循环加-卸载岩石本构模型研究[J]. 岩土力学, 2015, 36(12): 3354-3359.

[70]Lin Q, Cao P, Mao S, et al. Fatigue behaviour and constitutive model of yellow sandstone containing pre-existing surface crack under uniaxial cyclic loading[J]. Theoretical and Applied Fracture Mechanics, 2020, 109: 102776.

[71]Zhong Z, Li Y, Huang D. Prestress Loss Mechanism and Constitutive Model of an Anchored Joint Rock Mass Under Low-frequency Fatigue Loading[J]. Rock Mechanics and Rock Engineering, 2022: 1-19.

[72]郭建强, 黄质宏. 循环荷载作用下岩石疲劳本构模型初探[J]. 岩土工程学报, 2015, 37(09): 1698-1704.

[73]孙钧. 岩石流变力学及其工程应用研究的若干进展[J]. 岩石力学与工程学报, 2007(06): 1081-1106.