Mechanical Behavior of Dam Foundation with Vertical Sand Drain, Case Study: Sombar Dam


  • Mohammed Shaker Mahmood Department of Civil Engineering, Faculty of Engineering, Kufa University, Kufa, Al-Najaf,
  • Ali Akhtarpour Department of Civil Engineering, Ferdowsi University of Mashhad, Azadi Square, Mashhad, Razavi Khorasan, I.R.
  • Ameer Abdulridha Ajmi Alali Department of Civil Engineering, Ferdowsi University of Mashhad, Azadi Square, Mashhad, Razavi Khorasan, I.R.



earth dam, safety factor, sand drain, saturated soft soil, settlement, Sombar Dam


Installing vertical sand drains is a traditional dam foundation consolidation solution that is economical and provides good drainage efficiency. Vertical sand drains can shorten the path of water flow inside the soil and speeds up soil consolidation. This study investigated the effect of sand drains in the foundation of the Sombar Dam in Iran on its mechanical behavior. The Sombar Dam is a project to control flooding and provide agricultural water to Gholaman city in northeastern Iran. The investigation included the mechanical behavior of the dam with vertical sand drains. The studied parameters were drain diameter, depth and spacing in addition to the vertical-to-horizontal permeability ratio (ky/kx) of the foundation soil during the time of construction of the dam using a Mohr-Coulomb (MC) model in the software application GeoStudio. The results revealed that reducing the drain spacing (increasing the number of drains) and increasing the depth and diameter of the drains led to an increase of the settlement rate (up to 90%) and the stability of the dam over a shorter period of time (24 months) compared to no drain condition. With a decrease in the ratio of vertical-to-horizontal permeability (ky/kx=0.1) for all drain parameters there was a decrease in the value of the dam settlement rate and the safety factor.


Download data is not yet available.


Edil, T. & Berilgen, M., Construction of Earth Dams on Soft Ground: Principles and Examples, Conference US-China Workshop on Ground Improvement Technologies: Advances in Ground Improvement, pp. 298-307, 2009. DOI: 10.1061/41025(338)32.

Krishnamoorthy, A. & Kamal, S., Stability of an Embankment on Soft Consolidation Soil with Vertical Drains, Journal of Geotechnical and Geological Engineering, 34(2), pp. 657-669, 2016. DOI: 10.1007/s10706-015-9975-4.

Indraratna, B., Perera, D., Rujikiatkamjorn, C. & Kelly, R., Soil Disturbance Analysis due to Vertical Drain Installation, Proceedings of the Institution of Civil Engineers: Geotechnical Engineering, 168(3), pp. 236-246, 2012. DOI: 10.1680/geng.14.00052.

Indraratna, B., Rujikiatkamjorn, C., Wijeyakulasuriya, V., McIntosh, G. & Kelly, R., Soft Soils Improved by Prefabricated Vertical Drains: Performance and Prediction, in Almeida, Symposium on New Techniques for Design and Construction in Soft Clays, Brazil: Officna de Textos, pp. 227-246, 2010.

Indraratna, B., Rujikiatkamjorn, C., Balasubramaniam, A.S. & McIntosh, G., Soft Ground Improvement via Vertical Drains and Vacuum Assisted Preloading, 30(4), pp. 16-23, 2012. DOI: 10.1016/j.geotexmem.2011.01. 004.

Ozcoban, S., Berilgen, M.M., Kilic, H., Edil, T.B. & Ozaydin, I.K., Staged Construction and Settlement of a Dam Founded on Soft Clay, J. Geotech. Geoenviron. Eng., 133(8), pp. 1003-1016, 2007.

Giridhar Rajesh, B., Chukka, S.K. & Dey, A., Finite Element Modeling of Embankment Resting on Soft Ground Stabilized with Prefabricated Vertical Drains, Geotechnical Engineering, 49, pp. 63-72, 2018.

Coombs, W.M., Crouch, R. S. & Heaney, C.E. Observations on Mohr-Coulomb Plasticity under Plane Strain, J. Eng. Mech., ASCE, 139, pp. 1218-1228, 2013.

Sandhya Rani, R., Nagendra Prasad, K. & Sai Krishna, T., Applicability of Mohr-Coulomb & Drucker Prager Models for Assessment of Undrained Shear Behavior of Clayey Soils, International Journal of Civil Engineering and Technology (IJCIET), 5(10), pp. 104-123, 2014.

Dey, A., Vertical Drains and Smear Effects: A Brief Review, GeoSymposium 2008, National Symposium on GeoEnvironment, GeoHazards, Geosynthetics and Ground Improvement: Events and Practices, 4G, At New Delhi, India, pp. 333-341, 2008.

Dhar, A.S., Siddique, A. & Ameen, S.F., Ground Improvement using Pre-loading with Prefabricated Vertical Drains, International Journal of Geoengineering Case Histories,, 2(2), pp. 86-104, 2011.

Chai, J. & Miura, N., Investigation of Factors Affecting Vertical Drain Behavior, Journal of Geotechnical and Geoenvironmental Engineering, 125(3), pp. 216-226, 1999.

Indraratna, B., Plane-Strain Modeling of Smear Effects Associated with Vertical Drains, Journal 0f Geotechnical and Geoenvironmental Engineering, 123, pp. 474-478, 1997.

Alali, A., The Effect of Vertical Drains On Stability and Settlements During Construction of an Embankment Dam on Saturated Soft Soil (Case Study: Sombar Dam), M.Sc. Thesis, Faculty of Engineering, Ferdowsi University of Mashhad, Iran, 2017. (in Persian)

GeoStudio User's Manual (Sigma/w Modeling), 3rd Edition, 2012.

Carillo, N., Simple Two-and Three Dimensional Cases in the Theory of Consolidation of Soils, Journal of Mathematics and Physics, 21(1), pp. 1-5, 1942.

Indraratna, B., Bamunawita, C., Redana, I.W. & Mcintosh, G., Modelling of Prefabricated Vertical Drains in Soft Clay and Evaluation of Their Effectiveness in Practice, Journal of Ground Improvement, 7(3), pp. 127-138, 2003.