Document Type : Original Article


Department of Water Engineering, Faculty of Agriculture, University of Tabriz, Tabriz, Iran


Underground water levels and pore water pressure can be increased as a result of heavy rainfall which can lead failure of earthen slopes. Retaining walls are the most well-known structures in order to increase earthen slope stability. In this study, the stability of earthen slopes is numerically simulated in critical hydrological situations. The simulations included pore pressure behind the retaining walls which lead to instability. Among the investigated parameters were: precipitation intensity, soil type, position and the diameter of drainage passages. Both horizontal and chimney drainages were simulated for the study. For fine-grained soils with intensive precipitation, using a single horizontal drainage passageway could not maintain sufficient stability for the retaining wall. Precipitation could have severe impact on stability in which increase of 5 to 15 mm/h would increase pore pressure from 7.09 kN to 75.39 kN which is so dramatic change. For coarse-grained soils, a retaining wall provides stability with a single horizontal drainage pipe; the horizontal pipe is able to discharge all the excess water behind the retaining wall. A chimney drainage system provided the best results, and the stability of the retaining wall did not endanger, even under the worst circumstances. Linear and non-linear regression relations were produced in dimensionless form which are providing 0.97 for R2 and 0.11 for RMSE values which implys the accurcy of equations. The accuracy of the regression determine their usage in practical applications.


Main Subjects

  1. Salmasi, F., and Jafari, F., 2019. A Simple Direct Method for Prediction of Safety Factor of Homogeneous Finite Slopes. Geotechnical and Geological Engineering, 37(5), pp.3949–3959. Doi: 10.1007/s10706-019-00884-3
  2. Cheung, P.Y., Wong, M.C., and Yeung, H.Y., 2006. Application of rainstorm nowcast to real-time warning of landslide hazards in Hong Kong. In: WMO PWS, Workshop on Warnings of Real-Time Hazards by Using Nowcasting Technology. pp 9–13
  3. Stanton, T.E., 1948. California experience in stabilizing earth slopes through the installation of horizontal drains by the Hydrauger method. In: Proceedings of the International Conference on Soil Mechanics and Foundation Engineering, the Netherlands. pp 256–260
  4. Smith, T.W., and Stafford, G. V., 1957. Horizontal Drains on California Highways. Journal of the Soil Mechanics and Foundations Division, 83(3), pp.1–26. Doi: 10.1061/JSFEAQ.0000062
  5. Tong, P.Y.L., and Maher, R.O., 1975. Horizontal drains as a slope stabilizing measure. Journal of the Engineering Society of Hong Kong, 3(1), pp.15–27.
  6. Hutchinson, N.N., 1977. Assessment of the effectiveness of corrective measures in relation to geological conditions and types of slope movement. Bulletin of the International Association of Engineering Geology, 16(1), pp.131–155.
  7. Lamb, S.E., 1980. Embankment stabilization by use of horizontal drains. Transportation Research Record, (749), pp.6–10.
  8. Mallawaratchie, D.P., Thuraisamy, M., Jayamanne, J., and Attanayake, A.M.L., 1996. Stage 1-remedial measures for stabilizing landslide at Beragala on Beragala Haliela road. In: Proceedings of the 7th International Symposium on Landslides, Trondheim, Norway. pp 1759–1764.
  9. Santi, P.M., Dale Elifrits, C., and Liljegren, J.A., 2001. Design and installation of horizontal wick drains for landslide stabilization. Transportation Research Record, 1757(1), pp.58–66.
  10. Tsao, T.M., Wang, M.K., Chen, M.C., Takeuchi, Y., Matsuura, S., and Ochiai, H., 2005. A case study of the pore water pressure fluctuation on the slip surface using horizontal borehole works on drainage well. Engineering Geology, 78(1–2), pp.105–118. Doi: 10.1016/j.enggeo.2004.11.002
  11. Au, S.W.C., and Pang, K.K., 1993. A note on seepage from retaining wall weepholes. Quarterly Journal of Engineering Geology, 26(1), pp.19–24. Doi: 10.1144/GSL.QJEG.1993.026.01.03
  12. Fishman, Y.A., 2009. Stability of concrete retaining structures and their interface with rock foundations. International Journal of Rock Mechanics and Mining Sciences, 46(6), pp.957–966. Doi: 10.1016/j.ijrmms.2009.05.006
  13. Kloukinas, P., Scotto di Santolo, A., Penna, A., Dietz, M., Evangelista, A., Simonelli, A.L., Taylor, C., and Mylonakis, G., 2015. Investigation of seismic response of cantilever retaining walls: Limit analysis vs shaking table testing. Soil Dynamics and Earthquake Engineering, 77, pp.432–445. Doi: 10.1016/j.soildyn.2015.05.018
  14. Blake, J.R., Renaud, J.-P., Anderson, M.G., and Hencher, S.R., 2003. Prediction of rainfall-induced transient water pressure head behind a retaining wall using a high-resolution finite element model. Computers and Geotechnics, 30(6), pp.431–442. Doi: 10.1016/S0266-352X(03)00055-7
  15. Moharrami, A., Hassanzadeh, Y., Salmasi, F., Moradi, G., and Moharrami, G., 2014. Performance of the horizontal drains in upstream shell of earth dams on the upstream slope stability during rapid drawdown conditions. Arabian Journal of Geosciences, 7(5), pp.1957–1964. Doi: 10.1007/s12517-013-0872-y
  16. Rahardjo, H., Hritzuk, K.., Leong, E.., and Rezaur, R.., 2003. Effectiveness of horizontal drains for slope stability. Engineering Geology, 69(3–4), pp.295–308. Doi: 10.1016/S0013-7952(02)00288-0
  17. Pathmanathan, M.L., 2009. Numerical simulation of the performance of horizontal drains for subsurface slope stabilization. Doctoral dissertation, Washington State University.
  18. Athani, S.S., Shivamanth, Solanki, C.H., and Dodagoudar, G.R., 2015. Seepage and Stability Analyses of Earth Dam Using Finite Element Method. Aquatic Procedia, 4, pp.876–883. Doi: 10.1016/j.aqpro.2015.02.110
  19. Viswanadham, B.V.S., Razeghi, H.R., Mamaghanian, J., and Manikumar, C.H.S.G., 2017. Centrifuge model study on geogrid reinforced soil walls with marginal backfills with and without chimney sand drain. Geotextiles and Geomembranes, 45(5), pp.430–446. Doi: 10.1016/j.geotexmem.2017.06.005
  20. Boeckmann, A., Loehr, J.E., Friedman, K., Koenig, E., Roustio, R., and Runge, S., 2017. Design of Maintainable Drains for Earth Retaining Structures. Final Report and Design Guide, Department of Civil and Environmental Engineering, University of Missouri-Columbia.
  21. Salmasi, F., Pradhan, B., and Nourani, B., 2019. Prediction of the sliding type and critical factor of safety in homogeneous finite slopes. Applied Water Science, 9(7), pp.1–11. Doi: 10.1007/s13201-019-1038-1
  22. Geo-Slope International Ltd, 2007 Calgary, Canada.
  23. Khalili Shayan, H., and Amiri-Tokaldany, E., 2015. Effects of blanket, drains, and cutoff wall on reducing uplift pressure, seepage, and exit gradient under hydraulic structures. International Journal of Civil Engineering, 13(4), pp.486–500. Doi: 10.22068/IJCE.13.4.486
  24. USBR. Embankment dams., 2014. Chapter 8, phase 4. US Department of interior bureau of reclamation.
  25. Nouri, M., Sihag, P., Salmasi, F., and Abraham, J., 2021. Prediction of Homogeneous Earthen Slope Safety Factors Using the Forest and Tree Based Modelling. Geotechnical and Geological Engineering, 39(4), pp.2849–2862. Doi: 10.1007/s10706-020-01659-x
  26. Gupta, S.C., Ranaivoson, A., Edil, T.B., Benson, C.H., and Sawangsuriya, A., 2007. Pavement design using unsaturated soil technology. Report number: MN. RC-2007-11, Minnesota Department of Transportation, St. Paul, Minn.
  27. Hasani, H., Mamizadeh, J., and Karimi, H., 2013. Stability of slope and seepage analysis in earth fills dams using numerical models (case study: Ilam Dam-Iran). World Applied Sciences Journal, 21(9), pp.1398–1402.
  28. NAVFAC Design Manual 7.2, Foundations and Earth Structures., 1986. SN 0525-LP-300-7071, Revalidated by change, September.
  29. Salager, S., Nuth, M., Ferrari, A., and Laloui, L., 2013. Investigation into water retention behaviour of deformable soils. Canadian Geotechnical Journal, 50(2), pp.200–208. Doi: 10.1139/cgj-2011-0409
  30. Koloski, J.W., Schwarz, S.D., and Tubbs, D.W., 1989. Geotechnical properties of geologic materials. Engineering geology in Washington, 1, pp.19–24.
  31. Carter, M., and Bentley, S.P., 1991. Correlations of soil properties. Pentech press publishers.
  32. Meyerhof, G.G., 1956. Penetration Tests and Bearing Capacity of Cohesionless Soils. Journal of the Soil Mechanics and Foundations Division, 82(1), pp.136–142. Doi: 10.1061/JSFEAQ.0000001
  33. Fang, H.-Y., 2013. Foundation engineering handbook. Springer Science & Business Media.
  34. Truty, A., and Obrzud, R., 2011. The Hardening Soil Model a Practical Guidebook. Zace Serv Ltd, Softw Eng Lausanne.