Rainfall-Induced Stability of Reinforced Slopes with Twin Parallel Tunnels: Experimental Validation and Coupled Hydro-Mechanical Analysis
Downloads
Climate change has increased the frequency and intensity of extreme rainfall events, which significantly threatens slope stability by elevating pore-water pressure, reducing effective stress, and weakening soil strength. This study aims to investigate the rainfall-induced hydro-mechanical response of a fill slope containing twin parallel tunnels and to evaluate the effectiveness of reinforcement measures in improving slope stability under such conditions. A combined experimental–numerical approach was adopted. First, a physical model test of twin tunnels excavated within a slope was conducted to provide validation data for the numerical model. Subsequently, a parametric numerical analysis was performed using the finite element method implemented in PLAXIS 3D to simulate the coupled hydraulic–mechanical behavior of the slope–tunnel system under varying rainfall intensities and durations. Reinforcement measures, including piles and plates, were incorporated to assess their stabilizing performance. The results show that rainfall duration has a more significant influence on slope deformation and pore-water pressure than rainfall intensity. Reinforcement measures effectively reduce deformation and enhance slope stability, although they have limited influence on the overall saturation distribution. Reinforced slopes also exhibit increased total discharge due to preferential seepage along soil–structure interfaces. The novelty of this study lies in integrating physical model validation with three-dimensional coupled hydro-mechanical numerical analysis to comprehensively evaluate deformation, pore-water pressure, and seepage behavior in reinforced tunnel–slope systems under rainfall conditions.
Downloads
[1] Hwang, J., & Lall, U. (2024). Increasing dam failure risk in the USA due to compound rainfall clusters as climate changes. Npj Natural Hazards, 1(1), 27. doi:10.1038/s44304-024-00027-6.
[2] Xie, C., Xu, C., Huang, Y., Liu, J., Shao, X., Xu, X., Gao, H., Ma, J., & Xiao, Z. (2025). Advances in the study of natural disasters induced by the “23.7” extreme rainfall event in North China. Natural Hazards Research, 1, 1–13. doi:10.1016/j.nhres.2025.01.003.
[3] Zhuang, Y., Hu, X., He, W., Shen, D., & Zhu, Y. (2024). Stability Analysis of a Rocky Slope with a Weak Interbedded Layer under Rainfall Infiltration Conditions. Water (Switzerland), 16(4), 604. doi:10.3390/w16040604.
[4] Tian, C., Xiao, Z., Ye, F., Tong, Y., Cao, X., Sun, J., & Li, Z. (2025). The impact of extreme rainfall and drainage system failure on rock tunnels: A case study of deep-buried karst tunnel. Engineering Failure Analysis, 171, 109345. doi:10.1016/j.engfailanal.2025.109345.
[5] Tang, K., Liu, D., Xie, S., Qiu, J., Lai, J., Liu, T., & Fang, Y. (2024). Analysis of loess water migration regularity and failure response of tunnel structure under rainfall environment. Bulletin of Engineering Geology and the Environment, 83(6), 251. doi:10.1007/s10064-024-03715-9.
[6] Qian, W., Tang, X., Ma, X., & Wang, X. (2025). Mechanical Characteristics and Safety Evaluation of Tunnel Lining Structures in Karst Areas Under Heavy Rainfall Conditions. Buildings, 15(10), 1756. doi:10.3390/buildings15101756.
[7] Xu, S., Lei, H., Li, C., Liu, H., Lai, J., & Liu, T. (2021). Model test on mechanical characteristics of shallow tunnel excavation failure in gully topography. Engineering Failure Analysis, 119, 104978. doi:10.1016/j.engfailanal.2020.104978.
[8] Jiang, X., Wang, F., Yang, H., & Niu, J. (2018). Parameter Sensitivity of Shallow-Bias Tunnel with a Clear Distance Located in Rock. Advances in Civil Engineering, 5791354. doi:10.1155/2018/5791354.
[9] Choi, J. I., & Lee, S. W. (2010). Influence of Existing Tunnel on Mechanical Behavior of New Tunnel. KSCE Journal of Civil Engineering, 14(5), 773–783. doi:10.1007/s12205-010-1013-8.
[10] Kim, J.-W. (2012). A Study on the Stability of Asymmetrical Twin Tunnels in Alternating Rock Layers Using Scaled Model Tests. Journal of Korean Society for Rock Mechanics, 22(1), 22–31. doi:10.7474/tus.2012.22.1.022.
[11] Seo, H. J., Choi, H., Lee, K. H., Bae, G. J., & Lee, I. M. (2014). Pillar-reinforcement technology beneath existing structures: Small-scale model tests. KSCE Journal of Civil Engineering, 18(3), 819–826. doi:10.1007/s12205-014-1392-3.
[12] Ng, C. W. W., & Lu, H. (2014). Effects of the construction sequence of twin tunnels at different depths on an existing pile. Canadian Geotechnical Journal, 51(2), 173–183. doi:10.1139/cgj-2012-0452.
[13] Chen, R. P., Lin, X. T., Kang, X., Zhong, Z. Q., Liu, Y., Zhang, P., & Wu, H. N. (2018). Deformation and stress characteristics of existing twin tunnels induced by close-distance EPBS under-crossing. Tunnelling and Underground Space Technology, 82, 468–481. doi:10.1016/j.tust.2018.08.059.
[14] Zhao, W., Jia, P. J., Zhu, L., Cheng, C., Han, J., Chen, Y., & Wang, Z. Guo. (2019). Analysis of the additional stress and ground settlement induced by the construction of double-O-tube shield tunnels in sandy soils. Applied Sciences (Switzerland), 9(7), 1399. doi:10.3390/app9071399.
[15] Zhu, Z. G., Huang, S., & Zhu, Y. Q. (2012). Study of road surface settlement rule and controlled criterion for railway tunnel undercrossing highway. Yantu Lixue/Rock and Soil Mechanics, 33(2), 558.
[16] Song, Z., Mao, J., Tian, X., Zhang, Y., & Wang, J. (2019). Optimization analysis of controlled blasting for passing through houses at close range in super-large section tunnels. Shock and Vibration, 1941436. doi:10.1155/2019/1941436.
[17] Kaya, A., Akgün, A., Karaman, K., & Bulut, F. (2016). Understanding the mechanism of slope failure on a nearby highway tunnel route by different slope stability analysis methods: a case from NE Turkey. Bulletin of Engineering Geology and the Environment, 75(3), 945–958. doi:10.1007/s10064-015-0770-5.
[18] Fattah, M. Y., Shlash, K. T., & Salim, N. M. (2013). Prediction of settlement trough induced by tunneling in cohesive ground. Acta Geotechnica, 8(2), 167–179. doi:10.1007/s11440-012-0169-4.
[19] Lin, H., & Zhong, W. (2019). Influence of Rainfall Intensity and Its Pattern on the Stability of Unsaturated Soil Slope. Geotechnical and Geological Engineering, 37(2), 615–623. doi:10.1007/s10706-018-0631-7.
[20] Ma, K. C., Tan, Y. C., & Chen, C. H. (2011). The influence of water retention curve hysteresis on the stability of unsaturated soil slopes. Hydrological Processes, 25(23), 3563–3574. doi:10.1002/hyp.8081.
[21] Tu, G. xiang, Huang, D., & Deng, H. (2019). Reactivation of a huge ancient landslide by surface water infiltration. Journal of Mountain Science, 16(4), 806–820. doi:10.1007/s11629-018-5315-5.
[22] Rahardjo, H., Ong, T. H., Rezaur, R. B., & Leong, E. C. (2007). Factors Controlling Instability of Homogeneous Soil Slopes under Rainfall. Journal of Geotechnical and Geoenvironmental Engineering, 133(12), 1532–1543. doi:10.1061/(asce)1090-0241(2007)133:12(1532).
[23] Ng, C. W. W., & Shi, Q. (1998). A Numerical Investigation of the Stability of Unsaturated Soil Slopes Subjected to Transient Seepage. Computers and Geotechnics, 22(1), 1–28. doi:10.1016/S0266-352X(97)00036-0.
[24] Fredlund, D. G., & Rahardjo, H. (2025). Soil Mechanics for Unsaturated Soils. Soil Mechanics for Unsaturated Soils. John Wiley & Sons, New Jersey, United States. doi:10.1002/9780470172759.
[25] Duncan, J. M., Wright, S. G., & Brandon, T. L. (2014). Soil strength and slope stability. Wiley, New Jersey, United States.
- Authors retain all copyrights. It is noticeable that authors will not be forced to sign any copyright transfer agreements.
- This work (including HTML and PDF Files) is licensed under a Creative Commons Attribution 4.0 International License.
