Selecting the Safety and Cost Optimized Geo-Stabilization Technique for Soft Clay Slopes

Kennedy C. Onyelowe, Ahmed M. Ebid, Hisham A. Mahdi, Jair A. Baldovino

Abstract


Slope failure poses a serious threat to the built environment as it is currently one of the fundamental contributors to climate change fears across the world, and this threatens the environmental goals of the United Nations Sustainable Development Goals (UNSDGs) for the year 2050. In this research paper, an optimized geo-stabilization numerical model has been developed with a Plaxis 2D code under safety and cost optimization considerations for a 37 m high slope embankment located on a soft clay watershed with an infinite extension. The site was prepared with four monitoring wells installed at 2.5 m, 7.5 m, 12.5 m, and 21.5 m from the foot of the slope to measure the water level conditions, and samples were collected and tested in the laboratory to determine the hydraulic and shear strength and modulus of the soil. Seven (7) different simulation alternatives were considered in terms of the model solutions to be deployed under dry and wet states, which were slope steep (angle) reduction (Alt-1), dewatering (Alt-2), jet grouting (Alt-3), jet grouting/dewatering (Alt-4), slope reduction/jet grouting (Alt-5), slope reduction/dewatering (Alt-6), and slope reduction/jet grouting/dewatering (Alt-7). The finite element model implementation of the alternatives showed that Alt-2, Alt-3, and Alt-4 had FOS of less than 1.5 and were omitted because their stability considerations did not meet the requirements for the normal operating conditions of a slope and also the short-term and long-term stability conditions according to the literature. Alternatives 1, 5, 6, and 7 with FOS above 1.5 were selected for further optimization considerations. Economic and sustainability factors were selected and considered based on the cost in line with current average market prices, constructability, reliability, and the environmental impact needed to achieve the required earthwork, jet grouting, dewatering, and selected combinations. Finally, the Alt-1 (FOS = 1.505), though not the cheapest, was selected as the optimal choice in terms of reliability, constructability, and environmental impact. However, Alt-6 (FOS = 1.520) and Alt-7 (FOS = 1.508) are the most economical but ranked low in reliability and environmental impact considerations.

 

Doi: 10.28991/CEJ-2023-09-02-015

Full Text: PDF


Keywords


Soft Clay Slopes; Slope Stabilization; Jet Grouting; Finite Element Method; Plaxis 2D Code; Engineering Economy.

References


Onyelowe, K. C., Sujatha, E. R., Aneke, F. I., & Ebid, A. M. (2022). Solving geophysical flow problems in Luxembourg: SPH constitutive review. Cogent Engineering, 9(1). doi:10.1080/23311916.2022.2122158.

Song, L., Yu, X., Xu, B., Pang, R., & Zhang, Z. (2020). 3D slope reliability analysis based on the intelligent response surface methodology. Bulletin of Engineering Geology and the Environment, 80(2), 735–749. doi:10.1007/s10064-020-01940-6.

Onyelowe, K. C., Mojtahedi, F. F., Azizi, S., Mahdi, H. A., Sujatha, E. R., Ebid, A. M., Darzi, A. G., & Aneke, F. I. (2022). Innovative Overview of SWRC Application in Modeling Geotechnical Engineering Problems. Designs, 6(5), 69. doi:10.3390/designs6050069.

Sun, C., Chai, J., Ma, B., Luo, T., Gao, Y., & Qiu, H. (2019). Stability Charts for Pseudostatic Stability Analysis of 3D Homogeneous Soil Slopes Using Strength Reduction Finite Element Method. Advances in Civil Engineering, 2019. doi:10.1155/2019/6025698.

Sui, Z. F., Yuan, W., Yi, W., & Yang, W. (2021). Stability analysis of ecological slopes based on a 3D finite element model. Advances in Materials Science and Engineering, 2021. doi:10.1155/2021/3785943.

Cala, M., & Flisiak, J. (2020). Slope stability analysis with FLAC and limit equilibrium methods. FLAC and Numerical Modeling in Geomechanics, 111–114. doi:10.1201/9781003077527-18.

Johari, A., & Gholampour, A. (2018). A practical approach for reliability analysis of unsaturated slope by conditional random finite element method. Computers and Geotechnics, 102, 79–91. doi:10.1016/j.compgeo.2018.06.004.

Johari, A., & Talebi, A. (2019). Stochastic Analysis of Rainfall-Induced Slope Instability and Steady-State Seepage Flow Using Random Finite-Element Method. International Journal of Geomechanics, 19(8). doi:10.1061/(asce)gm.1943-5622.0001455.

Kamchoom, V., & Leung, A. K. (2018). Hydro-mechanical reinforcements of live poles to slope stability. Soils and Foundations, 58(6), 1423–1434. doi:10.1016/j.sandf.2018.08.003.

Wang, L., Wu, C., Gu, X., Liu, H., Mei, G., & Zhang, W. (2020). Probabilistic stability analysis of earth dam slope under transient seepage using multivariate adaptive regression splines. Bulletin of Engineering Geology and the Environment, 79(6), 2763–2775. doi:10.1007/s10064-020-01730-0.

Suhatril, M., Osman, N., Azura Sari, P., Shariati, M., & Marto, A. (2019). Significance of Surface Eco-Protection Techniques for Cohesive Soils Slope in Selangor, Malaysia. Geotechnical and Geological Engineering, 37(3), 2007–2014. doi:10.1007/s10706-018-0740-3.

Nguyen, T. S., Likitlersuang, S., & Jotisankasa, A. (2020). Stability analysis of vegetated residual soil slope in Thailand under rainfall conditions. Environmental Geotechnics, 7(5), 338–349. doi:10.1680/jenge.17.00025.

Zhou, T., Zhang, L., Cheng, J., Wang, J., Zhang, X., & Li, M. (2022). Assessing the rainfall infiltration on FOS via a new NSRM for a case study at high rock slope stability. Scientific Reports, 12(1), 11917. doi:10.1038/s41598-022-15350-z.

Chen, X., Zhang, L., Chen, L., Li, X., & Liu, D. (2019). Slope stability analysis based on the Coupled Eulerian-Lagrangian finite element method. Bulletin of Engineering Geology and the Environment, 78(6), 4451–4463. doi:10.1007/s10064-018-1413-4.

Lin, S., Zheng, H., Han, C., Han, B., & Li, W. (2021). Evaluation and prediction of slope stability using machine learning approaches. Frontiers of Structural and Civil Engineering, 15(4), 821–833. doi:10.1007/s11709-021-0742-8.

Wang, Z., Liu, B., Han, Y., Wang, J., Yao, B., & Zhang, P. (2020). Stability of inner dump slope and analytical solution based on circular failure: Illustrated with a case study. Computers and Geotechnics, 117. doi:10.1016/j.compgeo.2019.103241.

Dar, L. A., & Shah, M. Y. (2021). Deep-Seated Slope Stability Analysis and Development of Simplistic FOS Evaluation Models for Stone Column-Supported Embankments. Transportation Infrastructure Geotechnology, 8(2), 203–227. doi:10.1007/s40515-020-00134-7.

Reichenbach, P., Rossi, M., Malamud, B. D., Mihir, M., & Guzzetti, F. (2018). A review of statistically-based landslide susceptibility models. Earth-Science Reviews, 180, 60–91. doi:10.1016/j.earscirev.2018.03.001.

Liu, X., & Wang, Y. (2021). Probabilistic simulation of entire process of rainfall-induced landslides using random finite element and material point methods with hydro-mechanical coupling. Computers and Geotechnics, 132. doi:10.1016/j.compgeo.2020.103989.

Xu, J., Zhao, X., Li, P., & Zhang, M. (2021). Stability of a 3D unsaturated vertical cut slope subjected to variable rainfall infiltration. Computers and Geotechnics, 134. doi:10.1016/j.compgeo.2021.104110.

Sun, D. mei, Li, X. min, Feng, P., & Zang, Y. ge. (2016). Stability analysis of unsaturated soil slope during rainfall infiltration using coupled liquid-gas-solid three-phase model. Water Science and Engineering, 9(3), 183–194. doi:10.1016/j.wse.2016.06.008.

Jimenez Fernandez, J. C., Castanon-Jano, L., Gaute Alonso, A., Blanco-Fernandez, E., Gonzalez Fernandez, J. C., Centeno Gonzalez, V., Castro-Fresno, D., & Garcia-Sanchez, D. (2022). 3D numerical simulation of slope-flexible system interaction using a mixed FEM-SPH model. Ain Shams Engineering Journal, 13(2). doi:10.1016/j.asej.2021.09.019.

Boldrin, D., Leung, A. K., & Bengough, A. G. (2017). Correlating hydrologic reinforcement of vegetated soil with plant traits during establishment of woody perennials. Plant and Soil, 416(1–2), 437–451. doi:10.1007/s11104-017-3211-3.

Xiang, G., Wang, C. L., Bai, M. Z., Xu, Z. Y., & Yan, J. J. (2013). Stability analysis of slope under the condition of rainfall infiltration. Applied Mechanics and Materials, 405–408(9), 256–261. doi:10.4028/www.scientific.net/AMM.405-408.256.

Shaghaghi, T., Ghadrdan, M., & Tolooiyan, A. (2020). Design and Optimisation of Drainage Systems for Fractured Slopes Using the XFEM and FEM. Simulation Modelling Practice and Theory, 103. doi:10.1016/j.simpat.2020.102110.

Egbueri, J. C., Igwe, O., & Unigwe, C. O. (2021). Gully slope distribution characteristics and stability analysis for soil erosion risk ranking in parts of southeastern Nigeria: a case study. Environmental Earth Sciences, 80(7). doi:10.1007/s12665-021-09605-7.

Geitner, C., Mayr, A., Rutzinger, M., Löbmann, M. T., Tonin, R., Zerbe, S., Wellstein, C., Markart, G., & Kohl, B. (2021). Shallow erosion on grassland slopes in the European Alps – Geomorphological classification, spatio-temporal analysis, and understanding snow and vegetation impacts. Geomorphology, 373. doi:10.1016/j.geomorph.2020.107446.

Mahdi, I. M., Ebid, A. M., & Khallaf, R. (2020). Decision support system for optimum soft clay improvement technique for highway construction projects. Ain Shams Engineering Journal, 11(1), 213–223. doi:10.1016/j.asej.2019.08.007.

Mahdi, I. M., Arafat, H., Ebid, A. M., & El-Kadi, A. F. (2021). Decision model to identify the optimum retaining wall type for restricted highway projects sites. International Journal of Construction Management, 1–8. doi:10.1080/15623599.2021.1974151.


Full Text: PDF

DOI: 10.28991/CEJ-2023-09-02-015

Refbacks

  • There are currently no refbacks.




Copyright (c) 2023 Kennedy C Kennedy C. ONYELOWE, Ahmed M. Ebid, Hisham A. MAHDI, Jair D. J. A. BALDOVINO

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 International License.
x
Message