Advertisement

Static and Seismic Bearing Capacity of Strip Footings on Sand Overlying Clay Soils

  • Ali Rajaei
  • Amin KeshavarzEmail author
  • Arsalan Ghahramani
Research Paper
  • 23 Downloads

Abstract

This paper examined the ultimate bearing capacity of a strip footing located on a two-layer substrate composed of a sandy soil on a clay layer. The analysis was conducted through discontinuity layout optimization, which is an upper bound limit analysis. This study focused on various factors contributing to the problem, i.e. sand layer internal friction angle, sand layer thickness, clay layer undrained shear strength (cu), unit weight of soil layers (γ), footing width (B) and surcharge pressure (q). Failure in both soil layers was governed by the Mohr–Coulomb criterion. The bearing capacity improves when there are two layers of sand–clay soil in comparison to the homogeneous clay soil. Such improvement is intensified by increasing the internal friction angle and thickness of the sand layer and surcharge pressure. The maximum improvement of the bearing capacity was found in a scenario where the entire failure zone was within the sand layer. The pseudo-static method was used to examine the seismic mode. According to the results, the higher the sand internal friction angle and lower cu/(γB), the lower the decrease in the seismic bearing capacity compared to the static mode. Furthermore, the variations of failure surface in static and seismic modes were investigated. The results obtained in this study were compared against the results of other methods, indicating good consistency.

Keywords

Bearing capacity Strip footing Layered soil Limit analysis Discontinuity layout optimization 

References

  1. Burd H, Frydman S (1997) Bearing capacity of plane-strain footings on layered soils. Can Geotech J 34(2):241–253.  https://doi.org/10.1139/cgj-34-2-241 CrossRefGoogle Scholar
  2. Gilbert M, Smith C, Haslam I, Pritchard T (2010) Application of discontinuity layout optimization to geotechnical limit analysis problems. In: Proceedings of the 7th European conference in numerical methods in geotechnical engineering, Trondheim, pp 169–174.  https://doi.org/10.1201/b10551-31
  3. Haghbin M (2016) Bearing capacity of strip footings resting on granular soil overlying soft clay. Int J Civ Eng 14(7):467–477.  https://doi.org/10.1007/s40999-016-0067-5 CrossRefGoogle Scholar
  4. Hanna A, Meyerhof G (1980) Design charts for ultimate bearing capacity of foundations on sand overlying soft clay. Can Geotech J 17(2):300–303.  https://doi.org/10.1139/t80-030 CrossRefGoogle Scholar
  5. Huang M, Qin H-L (2009) Upper-bound multi-rigid-block solutions for bearing capacity of two-layered soils. Comput Geotech 36(3):525–529.  https://doi.org/10.1016/j.compgeo.2008.10.001 CrossRefGoogle Scholar
  6. Ibrahim KMHI (2014) Bearing capacity of circular footing resting on granular soil overlying soft clay. HBRC J 12(1):71–77.  https://doi.org/10.1016/j.hbrcj.2014.07.004 CrossRefGoogle Scholar
  7. Kraft LM Jr, Helfrich SC (1983) Bearing capacity of shallow footing, sand over clay. Can Geotech J 20(1):182–185.  https://doi.org/10.1139/t83-018 CrossRefGoogle Scholar
  8. Kumar J, Chakraborty M (2015) Bearing capacity of a circular foundation on layered sand–clay media. Soils Found 55(5):1058–1068.  https://doi.org/10.1016/j.sandf.2015.09.008 CrossRefGoogle Scholar
  9. Lee K, Cassidy M, Randolph M (2013) Bearing capacity on sand overlying clay soils: experimental and finite-element investigation of potential punch-through failure. Géotechnique 63(15):1271–1284.  https://doi.org/10.1680/geot.12.P.175 CrossRefGoogle Scholar
  10. Leshchinsky B (2015) Bearing capacity of footings placed adjacent to c′–ϕ′ slopes. J Geotech Geoenviron Eng 141(6):04015022.  https://doi.org/10.1061/(ASCE)GT.1943-5606.0001306 CrossRefGoogle Scholar
  11. LimitState (2015) Limitstate: geo manual v 3.2, sheffield, UKGoogle Scholar
  12. Meyerhof G (1974) Ultimate bearing capacity of footings on sand layer overlying clay. Can Geotech J 11(2):223–229.  https://doi.org/10.1139/t74-018 CrossRefGoogle Scholar
  13. Meyerhof G, Hanna A (1978) Ultimate bearing capacity of foundations on layered soils under inclined load. Can Geotech J 15(4):565–572.  https://doi.org/10.1139/t78-060 CrossRefGoogle Scholar
  14. Michalowski RL, Shi L (1995) Bearing capacity of footings over two-layer foundation soils. J Geotech Eng 121(5):421–428.  https://doi.org/10.1061/(ASCE)0733-9410(1995)121:5(421) CrossRefGoogle Scholar
  15. Myslivec A, Kysela Z (1978) The bearing capacity of building foundations. Elsevier, AmsterdamGoogle Scholar
  16. Okamura M, Kimura T, Takemura J (1997) Centrifuge model tests on bearing capacity and deformation of sand layer overlying clay. Soils Found 37(1):73–88.  https://doi.org/10.3208/sandf.37.73 CrossRefGoogle Scholar
  17. Okamura M, Kimura T, Takemura J (1998) Bearing capacity predictions of sand overlying clay based on limit equilibrium methods. Soils Found 38(1):181–194.  https://doi.org/10.3208/sandf.38.181 CrossRefGoogle Scholar
  18. Shiau J, Lyamin A, Sloan S (2003) Bearing capacity of a sand layer on clay by finite element limit analysis. Can Geotech J 40(5):900–915.  https://doi.org/10.1139/t03-042 CrossRefGoogle Scholar
  19. Smith C, Cubrinovski M (2011) Pseudo-static limit analysis by discontinuity layout optimization: application to seismic analysis of retaining walls. Soil Dyn Earthq Eng 31(10):1311–1323.  https://doi.org/10.1016/j.soildyn.2011.03.014 CrossRefGoogle Scholar
  20. Smith C, Gilbert M (2007) Application of discontinuity layout optimization to plane plasticity problems. In: Proceedings of the Royal Society of London A: mathematical, physical and engineering sciences, vol 2086, pp 2461–2484. The Royal SocietyGoogle Scholar
  21. Smith CC, Tatari A (2016) Limit analysis of reinforced embankments on soft soil. Geotext Geomembr 44(4):504–514.  https://doi.org/10.1016/j.geotexmem.2016.01.008 CrossRefGoogle Scholar
  22. Terzaghi K, Peck RB (1948) Soil mechanics in engineering practice. Wiley, New YorkGoogle Scholar
  23. Xie Y, Leshchinsky B (2015) Mse walls as bridge abutments: optimal reinforcement density. Geotext Geomembr 43(2):128–138.  https://doi.org/10.1016/j.geotexmem.2015.01.002 CrossRefGoogle Scholar
  24. Yamaguchi H (1963) Practical formula of bearing capacity value for two layered ground. In: Proceedings of 2nd Asian conference on SMFE, pp 99–105Google Scholar
  25. Zhu D, Lee C, Jiang H (2001) A numerical study of the bearing capacity factor n γ. Can Geotech J 38(5):1090–1096.  https://doi.org/10.1139/t01-023 CrossRefGoogle Scholar

Copyright information

© Shiraz University 2018

Authors and Affiliations

  1. 1.School of EngineeringPersian Gulf UniversityBushehrIran
  2. 2.Department of Civil EngineeringShiraz UniversityShirazIran

Personalised recommendations