近年來在氣候變遷的衝擊之下，溫度變化對於環境的影響愈發顯著，並且對於土壤的水力行為也有影響，土壤水分特徵曲線是描述土壤水力行為的重要指標，透過基質吸力與土壤有效飽和度之間的關係，可量化土壤的水力特性，進一步分析整體邊坡的穩定性。然而，對於溫度變化影響邊坡穩定性之研究尚不普遍。本研究旨在研究環境溫度變化對未飽和淺層邊坡的水力行為及穩定性之影響，建立一個研究框架以量化不同溫度下穩定流體流動條件下的未飽和邊坡安全係數。本研究基於非等溫土壤水分特徵曲線模型，透過量化受到溫度影響的土壤水力特性參數，以水力耦合分析模式HYDRUS 2D及The Slope Cube Module，在有限元素模式中進行二維穩態及暫態滲流分析，研究之非等溫模型考慮了溫度改變產生的熱效應對土壤水力特性之影響。接著基於未飽和土壤的非等溫有效應力理論納入邊坡穩定性分析，並使用局部安全係數理論進行邊坡穩定性之評估，相比傳統的邊坡穩定性分析方法，可評估邊坡內部不同位置點之安全係數隨時間變化情形，得知真實破壞面之形狀，提高分析的準確性。研究結果顯示，當環境溫度升高會使土壤的基質吸力、吸應力、有效應力以及局部安全係數下降，進而使土壤的整體強度變弱，其影響來自於表面張力、土壤-水接觸角以及浸沒焓的變化所導致。邊坡模型分析結果顯示，土壤在降雨入滲前後透過不同的持水機制所主導，溫度改變造成的變化趨勢也會不同，降雨情境下土壤穩定性變化主要受到吸應力變化與土壤入滲能力所主導，而溫度改變後在不同情況之下加劇了變化程度。研究結果提供了有關土壤力學性質與溫度之間關係的見解，這對於土壤穩定性和地質災害預防具有實質幫助。

The impact of climate change has recently increased the effects of temperature changes on the environment, including the hydraulic behavior of soils. The soil water characteristic curve (SWCC) is an important indicator of the hydraulic behavior of soils. By quantifying the relationship between matric suction and effective saturation, the hydraulic properties of soils can be evaluated, allowing for further analysis of slope stability. However, studies on the effects of temperature change on slope stability are limited. This study investigated the effects of environmental temperature changes on the hydraulic behavior and stability of unsaturated shallow slopes. A study framework was established to quantify the safety factors of unsaturated shallow slopes at different temperatures. This study is based on a non-isothermal soil water characteristic curve model that involves quantifying the temperature-dependent hydraulic properties of the soil. Hydraulic coupling analysis models HYDRUS 2D and The Slope Cube Module were used for the finite element modeling of steady-state and transient seepage two-dimensional analysis. The non-isothermal model used in this study considered the thermal impacts of temperature changes and their effects on soil hydraulic properties. A slope stability analysis was performed based on the theory of non-isothermal effective stress for unsaturated soil, and the local factor of safety (LFS) theory was used to evaluate slope stability. Compared with traditional slope stability analysis methods, the LFS method allows the assessment of safety factors at different locations on a slope over time, providing insight into the shape of the actual failure surface and improving the accuracy of the analysis. An increased temperature decreased the soil matric suction, suction stress, mean effective stress, and LFS, weakening the overall soil strength. These effects are owing to changes in the surface tension, enthalpy of immersion and contact angle. Slope modeling analysis showed that soils were dominated by different water retention mechanisms before and after rainfall infiltration, and the trends caused by temperature changes also changed accordingly. The variation in soil stability under rainfall conditions was mainly influenced by changes in suction stress and soil permeability. Furthermore, temperature changes exacerbated the extent of these variations under different circumstances. This study provides insights into the relationship between soil mechanical properties and temperature, which is valuable for maintaining soil stability and preventing geological hazards.

Bachmann, J., Horton, R., Grant, S. A., & van der Ploeg, R. R. "Temperature Dependence of Water Retention Curves for Wettable and Water-Repellent Soils." Soil Science Society of America Journal, 66(1), 44-52. 2002.
Bishop, A. W. "The Principle of Effective Stress." Teknisk Ukeblad, 39, 859-863. 1959.
Bo, M. W. "Impact of Global Warming on Stability of Natural Slopes." Proceedings of the 4th Canadian Conference on Geohazards : From Causes to Management. Presse de l’Université Laval, Québec, 594. 2008.
Brooks, R. H., & Corey, A. T. "Hydraulic Properties of Porous Media and Their Relation to Drainage Design." Transactions of the ASABE, 7, 26-0028. 1964.
Burck, U., Bals, Höhne, Nascimento, Tamblyn, Reuther. "The Climate Change Performance Index 2022." 2021.
Carsel, R. F., & Parrish, R. S. "Developing joint probability distributions of soil water retention characteristics." Water Resources Research, 24(5), 755-769. 1988.
Chen, C.-C., Wang, Y.-R., Wang, Y.-C., Lin, S.-L., Chen, C.-T., Lu, M.-M., & Guo, Y.-L. L. "Projection of future temperature extremes, related mortality, and adaptation due to climate and population changes in Taiwan." Science of the Total Environment, 760, 143373. 2021.
Chiang, F., Mazdiyasni, O., & AghaKouchak, A. "Evidence of anthropogenic impacts on global drought frequency, duration, and intensity." Nat Commun, 12(1), 2754. 2021.
Corominas, J., van Westen, C., Frattini, P., Cascini, L., Malet, J. P., Fotopoulou, S., . . . Smith, J. T. "Recommendations for the quantitative analysis of landslide risk." Bulletin of Engineering Geology and the Environment. 2014.
Cutter, S. L., A. Ismail-Zadeh, I. Alcántara-Ayala, O. Altan, D. N. Baker, S. Briceño, . . . McBean, G. A. "Global risks Pool knowledge to stem losses from disasters." Nature, 522(7556), 277-279. 2015.
Dorsey, N. E. "Properties of Ordinary Water-Substance in All Its Phases; Water-Vapor Water and All the Ices." New York, Reinhold. 1940.
Duncan, J. M., & Wright, S. G. "Soil Strength and Slope Stability." John Wiley & Sons Inc. 2005.
Fredlund, D. G., Rahardjo, H., & Fredlund, M. D. "Unsaturated Soil Mechanics in Engineering Practice." John Wiley & Sons. 2012.
Gardner, R. A. "Relation of Temperature to Moisture Tension of Soil." Soil Science, 79, 257–266. 1955.
Graham, J., Tanaka, N., Crilly, T., & Alfaro, M. "Modified Cam-Clay modeling of temperature effects in clays." Canadian Geotechnical Journal - CAN GEOTECH J, 38, 608-621. 2001.
Grant, S. A., & Bachmann, J. "Effect of temperature on capillary pressure." In Environmental Mechanics: Water, Mass and Energy Transfer in the Biosphere, 199-212. 2002.
Grant, S. A., & Salehzadeh, A. "Calculation of Temperature Effects on Wetting Coefficients of Porous Solids and Their Capillary Pressure Functions." Water Resources Research, 32(2), 261-270. 1996.
Haar, L., Gallagher, J. S., & Kell, G. S. "NBS/NRC steam tables thermodynamic and transport properties and computer programs for vapor and liquid states of water in SI units." United States. 1984.
Henny, L., Thorncroft, C. D., Hsu, H.-H., & Bosart, L. F. "Extreme Rainfall in Taiwan: Seasonal Statistics and Trends." Journal of Climate, 1-51. 2021.
Hsu, C.-Y., Ng, U.-C., Chen, C.-Y., Chen, Y.-C., Chen, M.-J., Chen, N.-T., . . . Wu, C.-D. "New land use regression model to estimate atmospheric temperature and heat island intensity in Taiwan." Theoretical and Applied Climatology, 141(3-4), 1451-1459. 2020.
Hsu, H.-H., Chia Chou, Yi-chao Wu, Mong-Ming Lu, Cheng-Ta Chen, & Chen, Y.-M. "Climate change in Taiwan scientific report 2011 (summary)." National Science Council, Taipei, Taiwan, ROC, 67pp. 2011.
Hsu, H. H., & Chen, C. T. "Observed and projected climate change in Taiwan." Meteorology and Atmospheric Physics, 79(1), 87-104. 2002.
Hu, C., Tam, C.-Y., Li, X., Huang, K., Ren, C., Fung, K. Y., & Wang, Z. "Mega-City Development Impact on Hourly Extreme Rainfall Over the South China Great Bay Area Under Near-Future Climate Warming." SSRN Electronic Journal. 2022.
Huang, J.-M., Chang, H.-Y., & Wang, Y.-S. "Spatiotemporal Changes in the Built Environment Characteristics and Urban Heat Island Effect in a Medium-Sized City, Chiayi City, Taiwan." Sustainability, 12(1). 2020.
IPCC. "Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. " Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA. 2013.
Khorshidi, M., Lu, N., Akin, I. D., & Likos, W. J. "Intrinsic Relationship between Specific Surface Area and Soil Water Retention." Journal of Geotechnical and Geoenvironmental Engineering, 143(1), 04016078. 2017.
Kosugi, K. i. "Lognormal Distribution Model for Unsaturated Soil Hydraulic Properties." Water Resources Research, 32(9), 2697-2703. 1996.
Kristo, C., Rahardjo, H., & Satyanaga, A. "Effect of hysteresis on the stability of residual soil slope." International Soil and Water Conservation Research, 7(3), 226-238. 2019.
Kueh, M. T., Lin, C. Y., Chuang, Y. J., Sheng, Y. F., & Chien, Y. Y. "Climate variability of heat waves and their associated diurnal temperature range variations in Taiwan." Environmental Research Letters, 12(7), 074017. 2017.
Lin, C.-Y., Chen, F., Huang, J. C., Chen, W. C., Liou, Y. A., Chen, W. N., & Liu, S.-C. "Urban heat island effect and its impact on boundary layer development and land–sea circulation over northern Taiwan." Atmospheric Environment, 42(22), 5635-5649. 2008.
Liu, H. H., & Dane, J. H. "Reconciliation between Measured and Theoretical Temperature Effects on Soil Water Retention Curves." Soil Science Society of America Journal, 57(5), 1202-1207. 1993.
Lu, N. "Generalized Soil Water Retention Equation for Adsorption and Capillarity." Journal of Geotechnical and Geoenvironmental Engineering, 142(10). 2016.
Lu, N., & Likos, W. J. "Suction Stress Characteristic Curve for Unsaturated Soil." Journal of Geotechnical and Geoenvironmental Engineering, 132(2), 131-142. 2006.
Lu, N., & Likos, W. J. "Unsaturated Soil Mechanics." John Wiley & Sons, Inc., Hoboken, 30-45. 2004.
Lu, N., Şener‐Kaya, B., Wayllace, A., & Godt, J. W. "Analysis of rainfall‐induced slope instability using a field of local factor of safety." Water Resources Research, 48(9). 2012.
Lu, N., Wayllace, A., & Chen, P. "The Slope Stress and Stability (Slope Cube) Module for HYDRUS (3D): Simulating Slope Stress and Stability in Variably-Saturated Soils." Hydrus Software Series 3.02.0290, PC-Progress. 2019.
Luo, P., Zhou, M., Deng, H., Lyu, J., Cao, W., Takara, K., . . . Geoffrey Schladow, S. "Impact of forest maintenance on water shortages: Hydrologic modeling and effects of climate change." Science of the Total Environment, 615, 1355-1363. 2018.
McQueen, I. S., & Miller, R. F. "Approximating soil moisture characteristics from limited data: Empirical evidence and tentative model." Water Resources Research, 10(3), 521-527. 1974.
Michalowski, R. L. "Stability Charts for Uniform Slopes." Journal of Geotechnical and Geoenvironmental Engineering, 128(4), 351-355. 2002.
Mitchell, J. K., & Soga, K. "Fundamentals of Soil Behavior, 3rd edition." New York: John Wiley and Sons. 2005
MnDOT Pavement Design Manual. "Minnesota Department of Transportation." St. Paul, Minnesota. 2007.
Mori, N., Takemi, T., Tachikawa, Y., Tatano, H., Shimura, T., Tanaka, T., . . . Nakakita, E. "Recent nationwide climate change impact assessments of natural hazards in Japan and East Asia." Weather and Climate Extremes, 32. 2021.
Mualem, Y. "A new model for predicting the hydraulic conductivity of unsaturated porous media." Water Resources Research, 12(3), 513-522. 1976.
Mukherjee, S., & Mishra, A. K. "Increase in Compound Drought and Heatwaves in a Warming World." Geophysical Research Letters, 48(1). 2021.
Nakhaei, M., Tafreshi, A. M., & Tafreshi, G. M. "A New Approach in Comparison and Evaluation of the Overall Accuracy of Six Soil-Water Retention Models Using Statistical Benchmarks and Fuzzy Method." Eurasian Soil Science, 54(5), 716-728. 2021.
Nimmo, J. R., & Miller, E. E. "The Temperature Dependence of Isothermal Moisture vs. Potential Characteristics of Soils." Soil Science Society of America Journal, 50(5), 1105-1113. 1986.
NOAA, N. O. a. A. A. "Climate at a Glance: Global Time Series." 2023.
Noor, M., Ismail, T., Chung, E.-S., Shahid, S., & Sung, J. "Uncertainty in Rainfall Intensity Duration Frequency Curves of Peninsular Malaysia under Changing Climate Scenarios." Water, 10(12). 2018.
Park, H. S., Song, Y.-S., & Park, S.-W. "Predicted Hydraulic Behavior in In-Situ Soil Slope Using the Path-Dependent Soil Water Characteristic Curve." Journal of the Korean Geotechnical Society, 33(4), 25-34. 2017.
Pradel, D., & Raad, G. "Effect of Permeability on Surficial Stability of Homogeneous Slopes." Journal of Geotechnical Engineering, 119(2), 315-332. 1993.
Rahardjo, H., Kim, Y., & Satyanaga, A. "Role of unsaturated soil mechanics in geotechnical engineering." International Journal of Geo-Engineering, 10(1). 2019.
Reddy, J. N. "Introduction to the Finite Element Method (4th Edition ed.)." New York: McGraw-Hill Education. 2019.
Revil, A., & Lu, N. "Unified water isotherms for clayey porous materials." Water Resources Research, 49(9), 5685-5699. 2013.
Richards, L. A. "Capillary conduction of liquids through porous mediums." Physics, 1(5), 318-333. 1931.
Romero, E., Gens, A., & Lloret, A. "Temperature effects on the hydraulic behaviour of an unsaturated clay." Geotechnical & Geological Engineering, 19(3), 311-332. 2001.
Roshani, P., & Sedano, J. Á. I. "Incorporating Temperature Effects in Soil-Water Characteristic Curves." Indian Geotechnical Journal, 46(3), 309-318. 2016.
Saito, H., Šimůnek, J., & Mohanty, B. P. "Numerical Analysis of Coupled Water, Vapor, and Heat Transport in the Vadose Zone." Vadose Zone Journal, 5(2), 784-800. 2006.
Šimůnek, J., van Genuchten, M. T., & Šejna, M. "Development and Applications of the HYDRUS and STANMOD Software Packages and Related Codes." Vadose Zone Journal, 7(2), 587-600. 2008.
Sánchez, M., Arson, C., Gens, A., & Aponte, F. "Analysis of unsaturated materials hydration incorporating the effect of thermo-osmotic flow." Geomechanics for Energy and the Environment, 6, 101-115. 2016.
Song, J. W., & Fan, L. W. "Temperature dependence of the contact angle of water: A review of research progress, theoretical understanding, and implications for boiling heat transfer." Adv Colloid Interface Sci, 288, 102339. 2021.
Terzaghi, K. "Theoretical Soil Mechanics." Wiley, New York. 1943.
Thota, S. K. "Temperature effects on unsaturated soils: constitutive relationships and emerging geotechnical applications." Theses and Dissertations. 4233. 2020.
Thota, S. K., Cao, T. D., Vahedifard, F., & Ghazanfari, E. "An Effective Stress Model for Unsaturated Soils at Elevated Temperatures." In Geo-Congress 2020, 358-366. 2020.
Thota, S. K., & Vahedifard, F. "Stability analysis of unsaturated slopes under elevated temperatures." Engineering Geology, 293. 2021.
Tung, Y.-S., Chen, C.-T., Min, S.-K., & Lin, L.-Y. "Evaluating Extreme Rainfall Changes over Taiwan Using a Standardized Index." Terrestrial, Atmospheric and Oceanic Sciences, 27(5), 705-715. 2016.
Uchaipichat, A. "Temperature and Suction Effects on Slope Stability under Undrained Condition." Applied Mechanics and Materials, 858, 98-103. 2017.
Uchaipichat, A., & Khalili, N. "Experimental investigation of thermo-hydro-mechanical behaviour of an unsaturated silt." Géotechnique, 59(4), 339-353. 2009.
Vahedifard, F., Cao, T. D., Ghazanfari, E., & Thota, S. K. "Closed-Form Models for Nonisothermal Effective Stress of Unsaturated Soils." Journal of Geotechnical and Geoenvironmental Engineering, 145(9). 2019.
Vahedifard, F., Cao, T. D., Thota, S. K., & Ghazanfari, E. "Nonisothermal Models for Soil–Water Retention Curve." Journal of Geotechnical and Geoenvironmental Engineering, 144(9). 2018.
van Genuchten, M. T. "A Closed-form Equation for Predicting the Hydraulic Conductivity of Unsaturated Soils." Soil Science Society of America Journal, 44(5), 892-898. 1980.
Vardon, P. J. "Climatic influence on geotechnical infrastructure: a review." Environmental Geotechnics, 2(3), 166-174. 2015.
Wang, H., Chen, R., Leung, A. K., & Huang, J. "Temperature effects on the hydraulic properties of unsaturated rooted soils." Canadian Geotechnical Journal, 60(6),936-945. 2023.
Watson, K. M.. "Thermodynamics of the Liquid State." Industrial & Engineering Chemistry, 35(4). 1943.
Wilkinson, G. E., & Klute, A. "The Temperature Effect on the Equilibrium Energy Status of Water Held by Porous Media." Soil Science Society of America Journal, 26(4), 326-329. 1962.
Winter, T. C., Harvey, J. W., Franke, O. L., & Alley, W. M. "Ground Water and Surface Water A Single Resource." US geological Survey. 1998.
Wu, C. "Using the Spatiotemporal Hot Spot Analysis and Multi-Annual Landslide Inventories to Analyze the Evolution and Characteristic of Rainfall-Induced Landslide at the Subwatershed Scale in Taiwan." Water, 15(7). 2023.