边坡的合理建设与防护能够有效减少地质灾害所造成的交通中断，经济损失，人员伤亡等不利影响。在自然或人类活动因素下，边坡岩体发生岩石风化作用，而岩石风化通常会涉及到水-岩相互作用。边坡岩体在经历反复不断的湿-热循环作用后，逐渐劣化、失稳，最终导致滑坡和崩塌等地质灾害。因此，研究边坡岩石经过湿-热循环作用后的劣化损伤机制具有非常重要的经济和社会意义。本文以铜川市耀州区为研究区域进行野外地质调查，选取区域内一处边坡脱落的砂岩岩体作为研究对象，将室内试验与理论相结合，分析了不同的循环次数和Na₂SO₄溶液浓度下，砂岩物理性质及声发射特征的变化规律，探究了湿-热循环作用对砂岩的影响机制。本文得到了以下认识：

（1）经过湿-热循环作用后，砂岩的质量呈现先增加后减少的趋势。在相同的循环次数下，Na₂SO₄溶液浓度越高质量损失越严重，损失速率越快。在8%浓度下，质量损失最严重，达到了0.66%。砂岩的色度明显变化，整体上从红色和蓝色谱系向绿色和黄色谱系转变，亮度先下降后升高，盐溶液浓度越高总色差越大。盐溶液对表面粗糙度有着显著影响，高盐溶液浓度下砂岩的粗糙度明显更大，并且随着循环次数的增加，粗糙度增长速率越来越快。在高盐溶液浓度下砂岩表面形成白色盐结晶薄层，矿物颗粒明显脱落，裂缝不断扩展延伸。对于砂岩的孔隙变化主要是以r＜0.1μm的微小孔隙数量减少、0.1μm＜r＜1μm的中孔数量增加为主。

（2）基于声发射技术研究了砂岩在加热处理过程中一些声发射特征值的变化。结果表明，声发射特征参数的变化分为三个阶段。阶段一0~200s时加热温度低，声发射活动和振铃计数较少，累计振铃计数缓慢增加，b值在一定范围内波动，表明微裂纹处于缓慢稳定扩展状态；阶段二200~700s时加热温度升高，声发射活动和振铃计数增多，累计振铃计数迅速增加，b值频繁大幅度波动，表明微裂纹处于不稳定破坏状态：阶段三为700~900s，砂岩破坏状态基本稳定，声发射活动和振铃计数开始减少，累计振铃计数趋于平稳，b值下降，表明微裂纹此时以大尺度破坏为主。

（3）随着循环次数的增加，砂岩声发射活动、振铃计数以及声发射信号总数显著增多，累计振铃计数峰值越来越高，岩石内部的拉张裂纹和剪切裂纹共同发育，大尺度拉张裂纹所占比例增多。在相同循环次数下，Na₂SO₄溶液浓度越高，低频率高幅度声发射信号、总信号数和累计振铃次数越多。Na₂SO₄溶液有利于大尺度剪切裂纹的发育，使砂岩热凯赛效应的阈值变得分散，加大了b值的离散度，从而影响岩石内部破坏的不稳定性。

（4）在湿-热循环过程中，盐结晶与矿物热损伤是岩石风化损伤的主要机制。盐结晶压力与矿物热膨胀应力使矿物晶体开裂并脱落，造成孔隙数量以及微裂纹大尺度宏观破坏显著增多，岩石内部微观结构发生变化。

Reasonable construction and protection of slope can effectively reduce traffic interruption, economic losses, casualties and other adverse effects caused by geological disasters. Rock weathering occurs in slope rock mass under natural or human activities, and rock weathering usually involves water-rock interaction. The rock mass of slope gradually deteriorates and becomes unstable after repeated wet-heat cycle, which eventually leads to geological disasters such as landslide and collapse. Therefore, it is of great economic and social significance to study the deterioration damage mechanism of slope rock after wet-heat cycle. In this paper, Yaozhou District of Tongchuan City is taken as the research area for field geological survey. Sandstone rock mass which fell off from a slope in the area is selected as the research object. By combining laboratory tests with theories, the change rules of physical properties and acoustic emission characteristics of sandstone under different cycle times and Na₂SO₄ solution concentration are analyzed, and the influence mechanism of wet-heat cycle on sandstone is explored. The main conclusions of this paper are as follows:

(1) After the wet-thermal cycle, the mass of sandstone increases first and then decreases. Under the same number of cycles, the higher the concentration of Na₂SO₄ solution, the more serious the mass loss and the faster the loss rate. At 8% concentration, the mass loss is the most serious, reaching 0.66%. The chroma of sandstone changes obviously, from red and blue pedigree to green and yellow pedigree on the whole, the brightness decreases first and then increases, the higher the concentration of salt solution, the greater the total color difference. Salt solution has a significant effect on the surface roughness. The roughness of sandstone is obviously greater under high salt solution concentration, and the roughness increases faster and faster with the increase of the number of cycles. Under high salt solution concentration, white salt crystal thin layer is formed on the surface of sandstone, mineral particles fall off obviously, and cracks continue to extend. For sandstone pore changes, the number of micropores (r＜0.1μm) decreases and the number of mesoporous pores (0.1μm＜r＜1μm) increases.

(2) Based on acoustic emission technology, the variation of some acoustic emission characteristic values of sandstone in the process of heating is studied. The results show that the variation of acoustic emission characteristic parameters can be divided into three stages. In stage 1, the heating temperature is low from 0 to 200s, the acoustic emission activity and ringing count are less, the cumulative ringing count increases slowly, and the b value fluctuates within a certain range, indicating that the microcrack is in a state of slow and stable growth. From 200 s to 700s, the heating temperature increased, the acoustic radiation activity and ringing count increased, the cumulative ringing count increased rapidly, and the b value fluctuated greatly and frequently, indicating the unstable failure state of the microcrack: The third stage is 700~900s, the failure state of sandstone is basically stable, the acoustic emission activity and ringing count begin to decrease, the cumulative ringing count tends to be stable, and the b value decreases, indicating that the microcracks are mainly large-scale failure.

(3) With the increase of the number of cycles, the acoustic emission activities, ringing counts and the total number of acoustic emission signals in sandstone increase significantly, and the cumulative ringing counts peak becomes higher and higher. The tensile cracks and shear cracks in rock develop together, and the proportion of large-scale tensile cracks increases. Under the same number of cycles, the higher the concentration of Na₂SO₄ solution, the higher the number of low frequency and high amplitude AE signals, the total number of signals and the cumulative ringing times. Na₂SO₄ solution is conducive to the development of large-scale shear cracks, which disperses the threshold of hot Kaiser effect and increases the dispersion of b value, thus affecting the instability of rock internal failure.

(4) Salt crystallization and mineral thermal damage are the main mechanisms of rock weathering damage in the process of wet-heat cycle. Salt crystallization pressure and mineral thermal expansion stress crack and fall off mineral crystals, resulting in a significant increase in the number of pores and microcracks in large-scale macroscopic damage, and changes in rock internal microstructure.

[1] 魏雄. 水位变化对库岸边坡稳定性影响研究[D]. 重庆大学, 2020.

[2] 何越磊, 姚令侃, 苏凤环. 松散体边坡灾害自组织临界性及工程应用研究[J]. 中国地质灾害与防治学报, 2005, 16(2):5.

[3] 张晓刚, 马保成, 朱英珍. 陕北黄土地区公路边坡灾害的非工程防治措施[J]. 交通企业管理, 2015, 06:59-60.

[4] 吴李泉, 张锋, 凌贤长,等. 强降雨条件下浙江武义平头村山体高边坡稳定性分析[J].岩石力学与工程学报, 2009, 28(06):1193-1199.

[5] 周家文, 徐卫亚, 邓俊晔, 等. 降雨入渗条件下边坡的稳定性分析[J].水利学报, 2008, 384(09):1066-1073.

[6] 何满潮. 滑坡地质灾害远程监测预报系统及其工程应用[J]. 岩石力学与工程学报, 2009, 28(06):1081-1090.

[7] 丁爱红, 韩辉, 邵亚凯. 滑坡地质灾害稳定性及治理方案研究[J]. 能源与环保, 2022, 44(07):22-26.

[8] Hua W, Dong S, Peng F, et al. Experimental investigation on the effect of wetting-drying cycles on mixed mode fracture toughness of sandstone[J]. International Journal of Rock Mechanics and Mining Sciences, 2017, 93:242-249.

[9] 王士天, 刘汉超, 张倬元, 等. 大型水域水岩相互作用及其环境效应研究[J]. 地质灾害与环境保护, 1997, (01):70-90.

[10] 傅晏. 干湿循环水岩相互作用下岩石劣化机理研究[D].重庆大学, 2010.

[11] Fisher J B, Boles J R. Water-rock interaction in Tertiary sandstones, San Joaquin basin, California, U.S.A.: Diagenetic controls on water composition[J]. Chemical Geology, 1990, 82(1-2):83-101.

[12] Hadizadeh J, Law R D. Water-weakening of sandstone and quartzite deformed at various stress and strain rates[J]. International Journal of Rock Mechanics and Mining Sciences and Geomechanics Abstracts, 1991, 28(5):431-439.

[13] Noor-E-Khuda S, Albermani F. Flexural strength of weathered granites under wetting-drying cycles: implications to steel structures[J]. Advanced Steel Construction, 2019, 15(3):225-231.

[14] Noor-E-Khuda S, Albermani F, Veidt M. Flexural strength of weathered granites: Influence of freeze and thaw cycles[J]. Construction and Building Materials, 2017, 156(15):891-901.

[15] Cardell C, Rivas T, et al. Patterns of damage in igneous and sedimentary rocks under conditions simulating sea-salt weathering[J]. Earth Surface Processes and Landforms, 2003, 28:1-14.

[16] Vázquez P, Alonso F J. Colour and roughness measurements as ndt to evaluate ornamental granite decay[J]. Procedia Earth and Planetary Science, 2015, 15:213-218.

[17] Alonso F J, Vázquez P, Esbert R M, et al. Ornamental granite durability: evaluation of damage caused by salt crystallization[J]. Materiales De Construccion, 2008, 58(289).

[18] Yao W M, Li C D, Zhan H B, et al. Multiscale study of physical and mechanical properties of sandstone in three gorges reservoir region subjected to cyclic wetting-drying of Yangtze River water[J]. Rock Mechanics and Rock Engineering, 2020, 53 (5).

[19] 黄震, 胡钊健, 张海, 等.干湿循环下宁明粉砂岩宏微观损伤劣化规律[J].科学技术与工程,2022,22(12):4954-4961.

[20] Sun Q, Zhang YL. Combined effects of salt, cyclic wetting and drying cycles on the physical and mechanical properties of sandstone[J]. Engineering Geology, 2019, 248:70-79.

[21] Zhao F, Sun Q, Zhang W. Combined effects of salts and wetting-drying cycles on granite weathering[J]. Bulletin of Engineering Geology and the Environment, 2020, 79:3707-3720.

[22] Ozbek A. Investigation of the effects of wetting-drying and freezing-thawing cycles on some physical and mechanical properties of selected ignimbrites[J]. Bulletin of engineering geology and the environment, 2014, 73(2):595-609.

[23] Hale P A. A Laboratory Investigation of the Effects of Cyclic Heating and Cooling, Wetting and Drying, and Freezing and Thawing on the Compressive Strength of Selected Sandstones[J]. Environmental and Engineering Geoscience, 2003, 9(2):117-130.

[24] Khanlari G, Abdilor Y. Influence of wet-dry, freeze-thaw, and heat-cool cycles on the physical and mechanical properties of Upper Red sandstones in central Iran[J]. Bulletin of Engineering Geology and the Environment, 2015, 74(4):1287-1300.

[25] Dove P M, Elston S F. Dissolution kinetics of quartz in sodium chloride solutions: Analysis of existing data and a rate model for 25°C[J]. Geochimica Et Cosmochimica Acta, 1992, 56(12):4147-4156.

[26] Hall K, Hall A. Weathering by wetting and drying: Some experimental results [J]. Earth Surface Processes and Landforms, 1996, 21(4):365-376.

[27] Diop S, Ogawa Y, Zhang M. Effects of Cyclic Desiccation on Physical and Mechanical Properties of Neogene Sandstones and Siltstones From Boso Peninsula, Japan[C]. Agu Fall Meeting. AGU Fall Meeting Abstracts, 2006.

[28] 王伟, 龚传根, 朱鹏辉, 等. 大理岩干湿循环力学特性试验研究[J]. 水利学报, 2017, 48(10):1175-1184.

[29] 朱江鸿, 韩淑娴, 童艳梅, 等. 干湿循环对不同密度砂岩强度劣化的影响[J]. 华南理工大学学报, 2019, 47(3):126-134.

[30] 刘帅, 杨更社, 董西好. 干湿循环对红砂岩力学特性及损伤影响试验研究[J]. 煤炭科学技术, 2019, 47(4):101-106.

[31] 刘新荣, 袁文，傅晏，等. 化学溶液和干湿循环作用下砂岩抗剪强度劣化试验及化学热力学分析[J]. 岩石力学与工程学报, 2016, 35(12):2534-2541.

[32] 傅晏, 袁文, 刘新荣, 等. 酸性干湿循环作用下砂岩强度参数劣化规律[J]. 岩土力学, 2018，39(9):3331-3339.

[33] 陈绪新, 付厚利, 秦哲. 干湿循环作用下露天矿边坡岩石损伤能量演化分析[J]. 科学技术与工程, 2016, 16(20):247-252.

[34] Yao H Y, Zhang Z H, Zhu C H, et al. Mechanical properties of sandstone after cyclic drying and wetting[J]. rock and soil mechanics, 2011, 31(12):3704-3708.

[35] Ma C, Zhan H, Zhang T, et al. Investigation on shear behavior of soft interlayers by ring shear tests[J]. Engineering Geology, 2019, 254:34-42.

[36] Zhao Z, Yang J, Zhang D, et al. Effects of Wetting and Cyclic Wetting-Drying on Tensile Strength of Sandstone with a Low Clay Mineral Content[J]. Rock Mechanics and Rock Engineering, 2017, 50(2):485-491.

[37] Zhou Z, Cai X, Ma D, et al. Dynamic tensile properties of sandstone subjected to wetting and drying cycles[J]. Construction and Building Materials, 2018, 182(10):215-232.

[38] 傅晏, 刘新荣, 张永兴, 等. 水岩相互作用对砂岩单轴强度的影响研究[J]. 水文地质工程地质, 2009, 36(006):54-58.

[39] 刘新荣, 李栋梁, 王震, 等. 酸性干湿循环对泥质砂岩强度特性劣化影响研究[J]. 岩石力学与工程学报, 2016, 35(8):12.

[40] Zhang S, Xu Q, Hu Z. Effects of rainwater softening on red mudstone of deep-seated landslide, Southwest China[J]. Engineering Geology, 2016.

[41] 李男, 徐辉, 胡斌. 干燥与饱水状态下砂岩的剪切蠕变特性研究[J]. 岩土力学, 2012, 33(2):439443.

[42] Yuan W, Liu X, Fu Y. Study on Deterioration of Strength Parameters of Sandstone Under the Action of Dry-Wet Cycles in Acid and Alkaline Environment[J]. Arabian Journal for Science and Engineering, 2017, 43(1):335-348.

[43] Pardini G, Guidi G V, Pini R, et al. Structure and porosity of smectitic mudrocks as affected by experimental wetting-drying cycles and freezing-thawing cycles[J]. Catena, 1996, 27(3-4):149-165.

[44] Dunn K J, Bergman J D, Latorraca A G. Nuclear magnetic resonance: Petrophysical and logging applications[M]. Pergamon, 2002.

[45] Xu J, Li Y, Ren C, et al. Damage of saline intact loess after dry-wet and its interpretation based on SEM and NMR[J]. Soils and Foundations, 2020, 60:911–928.

[46] Liu C, Shi B, Zhou J, et al. Quantification and characterization of microporosity by image processing, geometric measurement and statistical methods: Application on SEM images of clay materials[J]. Applied Clay Science, 2011, 54(1):97-106.

[47] 唐朝生, 施斌, 王宝军. 基于SEM土体微观结构研究中的影响因素分析[J]. 岩土工程学报, 2008, 30(4):6.

[48] 谢凯楠, 姜德义, 孙中光, 等. 基于低场核磁共振的干湿循环对泥质砂岩微观结构劣化特性的影响[J]. 岩土力学, 2019(2):8.

[49] 刘新荣, 李栋梁, 张梁, 等. 干湿循环对泥质砂岩力学特性及其微细观结构影响研究[J]. 岩土工程学报, 2016,38(07):1291-1300.

[50] 宋勇军, 张磊涛, 任建喜, 等. 基于核磁共振技术的弱胶结砂岩干湿循环损伤特性研究[J]. 岩石力学与工程学报, 2019,38(04):825-831.

[51] Desarnaud J, Bertrand F, Shahidzadehbonn N. Impact of the kinetics of salt crystallization on stone damage during rewetting/drying and humidity cycling[J]. Journal of Applied Mechanics, 2013, 80(2):1-7.

[52] 姚远. 利用CT扫描研究干湿循环泥岩软化过程[J]. 工程勘察, 2014,42(06):12-15.

[53] 卢再华, 陈正汉, 蒲毅彬. 膨胀土干湿循环胀缩裂隙演化的CT试验研究[J]. 岩土力学, 2002(04):417-422.

[54] 杨更社. 岩石细观损伤力学特性及本构关系的CT识别[J]. 煤炭学报, 2000(1):102-106.

[55] Cardell C, Benavente D, Rodríguez-Gordillo J. Weathering of limestone building material by mixed sulfate solutions. Characterization of stone microstructure, reaction products and decay forms[J]. Materials Characterization, 2008, 59(10):1371-1385.

[56] Goudie A, Viles H. Salt Weathering Hazards.Wiley and Sons, 1997, 4:241.

[57] Coussy O. Deformation and stress from in-pore drying-induced crystallization of salt[J]. Journal of the Mechanics and Physics of Solids, 2006, 54(8):1517-1547.

[58] Benavente D, Martínez-Martínez J, Cueto N, et al. Salt weathering in dual-porosity building dolostones[J]. Engineering Geology, 2007, 94(3–4):215–226.

[59] Huang Y H, Yang S Q, Li W P, et al. Influence of Super-Critical CO2 on the Strength and Fracture Behavior of Brine-Saturated Sandstone Specimens[J]. Rock Mechanics and Rock Engineering, 2020, 53:653-670.

[60] 陈颙. 声发射技术在岩石力学研究中的应用[J]. 地球物理学报, 1977(04):312-322.

[61] 姜永东, 鲜学福, 许江. 岩石声发射Kaiser效应应用于地应力测试的研究[J]. 岩土力学, 2005(06):946-950.

[62] 陈宇龙, 魏作安, 许江, 等. 单轴压缩条件下岩石声发射特性的实验研究[J]. 煤炭学报, 2011, 36(S2):237-240.

[63] Barron K. Detection of fracture initiation in rock specimens by the use of a simple ultrasonic listening device[J]. International Journal of Rock Mechanics and Mining Sciences and Geomechanics Abstracts, 1971, 8(1):55-59.

[64] Moradian Z, Einstein H H, Ballivy G. Detection of Cracking Levels in Brittle Rocks by Parametric Analysis of the Acoustic Emission Signals[J]. Rock Mechanics & Rock Engineering, 2016, 49(3):785-800.

[65] 程爱平, 舒鹏飞, 张玉山, 等. 充填体-围岩组合体声发射特征与损伤本构研究[J]. 采矿与安全工程学报, 2020, 37(06):1238-1245.

[66] Gutenberg B, Richter C F. Frequency of Earthquakes in California[J]. Bulletin of the Seismological Society of America, 1994, 34(4):185-188.

[67] 吕培苓, 吴开统, 焦远碧, 等. 岩石蠕变过程中声发射活动的实验研究[J]. 地震学报, 1991(01):104-112.

[68] 李元辉, 刘建坡, 赵兴东, 等. 岩石破裂过程中的声发射b值及分形特征研究[J]. 岩土力学, 2009, 30(09):2559-2563.

[69] 刘希灵, 潘梦成, 李夕兵, 等. 动静加载条件下花岗岩声发射b值特征的研究[J]. 岩石力学与工程学报, 2017, 36(1):3148-3155.

[70] Gutenberg B, Richter C F. Frequency of Earthquakes in California[J]. Bulletin of the Seismological Society of America, 1994, 34(4):185-188.

[71] Cox S Jd, Meredith P G. Microcrack formation and material softening in rock measured by monitoring acoustic emissions[J]. International Journal of Rock Mechanics and Mining Sciences and Geomechanics Abstracts, 1993, 30(1):11-24.

[72] Pickering G, Bull J M, Sanderson. Sampling power-law distributions[J]. Tectonophysics, 1995, 248:1-20.

[73] Zhang H, Sun Q, Jia H, et al. Effects of high-temperature thermal treatment on the porosity of red sandstone: an NMR analysis[J]. Acta Geophysica, 2021, 69(1): 113-124.

[74] 秦红璐, 要惠芳, 贾小宝, 等. 基于NMR的深部煤储层孔裂隙特征[J]. 煤炭技术, 2019, 38(08): 55-8.

[75] 龚囱, 李长洪, 赵奎. 红砂岩短时蠕变声发射b值特征[J]. 煤炭学报, 2015, 40(S1):85-92.

[76] 曾正文, 马瑾, 刘力强, 等. 岩石破裂扩展过程中的声发射b值动态特征及意义[J]. 地震地质, 1995(01):7-12.

[77] Barbara L, Rob P J, Van H, et al. The role of sea salts in the occurrence of different damage mechanisms and decay patterns on brick masonry[J]. Construction and Building Materials, 2004, 18(2), 119–124.

[78] 张汝藩. 扫描电镜在矿物变化研究中的应用-长石的粘土矿物转化[J]. 地质科学, 1992(01): 66-70.

[79] Lubelli B, Hees R, Groot C. The role of sea salts in the occurrence of different damage mechanisms and decay patterns on brick masonry[J]. Construction and Building Materials, 2004, 18(2):119-124.

[80] Winkler E M. Stone in Architecture [M]. Stone in Architecture, 2011.

[81] Hu X, Song X, Liu Y, et al. Experiment investigation of granite damage under the high-temperature and high-pressure supercritical water condition[J]. Journal of Petroleum Science and Engineering, 2019, 180: 289-97.

[82] Somerton W H. Additional Thermal Data for Porous Rocks-Thermal Expansion and Heat of Reaction[J]. Soc Pet Eng J, 1961, 1:4(04): 249-53.