FEM Optimisation of Seepage Control System Used for Base Stability of Excavation

Ilyes Ouzaid, Naïma Benmebarek, Sadok Benmebarek


With the existence of a high groundwater level, the head difference between the inside and outside of an excavation may lead to the loss of stability of the excavation’s surface. Hence, a fundamental understanding of this occurrence is important for the design and construction of water-retaining structures. In some cases, the failure mechanism cannot be predicted exactly because of its mechanical complexity as well as a major lack of protection systems and not adopting effective countermeasures against this phenomenon. The article took a tranche from an 80 km long open sewer located in the Ruhr area, Germany as an example to establish a hydro-geological model and analyse the instability of the excavation base surface caused by the groundwater flow at 45m deep and to present the effectivity of an adopted drainage system inside the excavation pit as 39 columns of sand to relax the pore water pressure. By using the Finite Element Method (FEM) analysis, the failure mechanism was investigated before applying any countermeasures, and the total length of the adopted countermeasure system was minimised. Also, various position tests were performed on the adopted drainage system to confirm the optimised position. The results of this numerical study allowed the deduction of the importance of the used drainage system by achieving 44% more in the excavating process. After achieving the required excavation depth, a further increase of the sand columns’ penetration may be considered non-economic because, after adding extra depth, all the situations have the same safety factor. In addition, this can provide a reference for the optimised position of the sand columns where they must be applied right by the wall and limited by a critical distance, D/2, half of the embedded depth of the wall.


Factor of Safety; Failure Mechanism; Deep Circular Excavation; Finite Element Method; Drainage System.


Ou, Chang-Yu. “Deep Excavation” (April 21, 2014). doi:10.1201/9781482288469.

“Eurocode 7. Geotechnical Design” (2004). doi:10.3403/03181153u.

Terzaghi, Karl. “Theoretical Soil Mechanics. Johnwiley & Sons.” New York (1943): 11–15.

Tanaka, Tsutomu, and Arnold Verruijt. “Seepage Failure of Sand behind Sheet Piles—The Mechanism and Practical Approach to Analyse —.” Soils and Foundations 39, no. 3 (June 1999): 27–35. doi:10.3208/sandf.39.3_27.

Sun, Yu-yong. “Experimental and Theoretical Investigation on the Stability of Deep Excavations against Confined Aquifers in Shanghai, China.” KSCE Journal of Civil Engineering 20, no. 7 (January 22, 2016): 2746–2754. doi:10.1007/s12205-016-0488-3.

Benmebarek, N., S. Benmebarek, and R. Kastner. “Numerical Studies of Seepage Failure of Sand within a Cofferdam.” Computers and Geotechnics 32, no. 4 (June 2005): 264–273. doi:10.1016/j.compgeo.2005.03.001.

Benmebarek, N., A. Bensmaine, S. Benmebarek, and L. Belounar. “Critical Hydraulic Head Loss Inducing Failure of a Cofferdam Embedded in Horizontal Sandy Ground.” Soil Mechanics and Foundation Engineering 51, no. 4 (September 2014): 173–180. doi:10.1007/s11204-014-9274-8.

Aulbach, Benjamin, and Martin Ziegler. “Simplified Design of Excavation Support and Shafts for Safety against Hydraulic Heave / Einfache Bemessung von Baugruben Und Schächten Im Hinblick Auf Die Sicherheit Gegen Hydraulischen Grundbruch.” Geomechanics and Tunnelling 6, no. 4 (August 2013): 362–374. doi:10.1002/geot.201300031.

Koltuk, Serdar, Jie Song, Recep Iyisan, and Rafig Azzam. “Seepage Failure by Heave in Sheeted Excavation Pits Constructed in Stratified Cohesionless Soils.” Frontiers of Structural and Civil Engineering 13, no. 6 (September 27, 2019): 1415–1431. doi:10.1007/s11709-019-0565-z.

Madanayaka, Thushara Asela, and Nagaratnam Sivakugan. “Validity of the Method of Fragments for Seepage Analysis in Circular Cofferdams.” Geotechnical and Geological Engineering 38, no. 2 (October 31, 2019): 1547–1565. doi:10.1007/s10706-019-01111-9.

Koltuk, Serdar, and Rafig Azzam. “Use of Quicksand Condition to Assess the Base Stabilities of Sheeted Excavation Pits Against Seepage Failure in Cohesionless Soils.” Arabian Journal for Science and Engineering 44, no. 10 (May 2, 2019): 8515–8526. doi:10.1007/s13369-019-03890-y.

Marsland, Arthur. “Model Experiments to Study the Influence of Seepage on the Stability of a Sheeted Excavation in Sand.” Géotechnique 3, no. 6 (June 1953): 223–241. doi:10.1680/geot.1953.3.6.223.

Aulbach, Benjamin, Martin Ziegler, and Holger Schüttrumpf. “Design Aid for the Verification of Resistance to Failure by Hydraulic Heave.” Procedia Engineering 57 (2013): 113–119. doi:10.1016/j.proeng.2013.04.017.

Faheem, Hamdy, Fei Cai, Keizo Ugai, and Toshiyuki Hagiwara. “Two-Dimensional Base Stability of Excavations in Soft Soils Using FEM.” Computers and Geotechnics 30, no. 2 (March 2003): 141–163. doi:10.1016/s0266-352x(02)00061-7.

Zhang, Fan, and Anthony T. C. Goh. “Finite Element Analysis of Basal Heave Stability for Braced Excavations in Clays.” Japanese Geotechnical Society Special Publication 2, no. 44 (2016): 1551–1554. doi:10.3208/jgssp.atc6-03.

Pratama, Ignatius Tommy, and Chang-Yu Ou. “Analysis of Sand Boiling Failure in Deep Excavations.” Proceedings of the 2nd International Symposium on Asia Urban GeoEngineering (2018): 125–141. doi:10.1007/978-981-10-6632-0_10.

Fontana, Nicola. “Experimental Analysis of Heaving Phenomena in Sandy Soils.” Journal of Hydraulic Engineering 134, no. 6 (June 2008): 794–799. doi:10.1061/(asce)0733-9429(2008)134:6(794).

Yousefi, Mehdi, Mohammad Sedghi-Asl, and Mansour Parvizi. “Seepage and Boiling Around a Sheet Pile under Different Experimental Configuration.” Journal of Hydrologic Engineering 21, no. 12 (December 2016): 06016015. doi:10.1061/(asce)he.1943-5584.0001449.

Zhao, Guo-qing, Yu-you Yang, and Su-yun Meng. “Failure of Circular Shaft Subjected to Hydraulic Uplift: Field and Numerical Investigation.” Journal of Central South University 27, no. 1 (January 2020): 256–266. doi:10.1007/s11771-020-4293-2.

Pane, Vincenzo, Diego Bellavita, Manuela Cecconi, and Alessia Vecchietti. “Hydraulic Failure of Diaphragm Walls: a Possible Methodology for Safety Improvement.” Geotechnical and Geological Engineering 35, no. 2 (December 27, 2016): 765–780. doi:10.1007/s10706-016-0140-5.

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DOI: 10.28991/cej-2020-03091579


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