Geomechanics and Engineering

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Failure mechanism and bearing capacity of inclined skirted footings

  • Rajesh P. Shukla (Department of Civil Engineering, National Institute of Technology) ;
  • Ravi S. Jakka (Department of Earthquake Engineering, IIT Roorkee)
  • Received : 2021.10.14
  • Accepted : 2023.08.21
  • Published : 2023.10.10
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Abstract

The use of a skirt, a vertical projection attached to the footing, is a recently developed method to increase the bearing capacity of soils and reduce foundation settlements. Most of the studies were focused on vertical skirted circular footings resting on clay while neglecting the rigidity and inclination of skirts. This study employs finite element limit analysis to investigate the bearing capacity enhancement of flexible and rigid inclined skirts in cohesionless soils. The results indicate that the bearing capacity initially improves with an increase in the skirt inclination but subsequently decreases for both flexible and rigid skirts. However, the rigid skirt exhibits more apparent optimum skirt inclination and bearing capacity enhancement than the flexible one, owing to differences in their failure mechanisms. Furthermore, the bearing capacity of the inclined skirted foundation increases with the skirt length, footing depth, and internal friction angle of the soil. In the case of rigid skirts, the bearing capacity increases linearly with skirt length, while for flexible skirts, it reaches a stable value at a certain skirt length. The efficiency of the flexible footing reduces as the footing depth and soil internal friction angle increase. Conversely, the efficiency of the rigid skirt decreases only with an increase in the depth of the footing. The paper also presents a detailed analysis of various failure patterns, highlighting the behaviour of inclined skirted footings. Additionally, nonlinear regression equations are provided to quantify and predict the bearing capacity enhancement with the inclined skirts.

Keywords

References

  1. Al-Aghbari, M.Y. and Mohamedzein, Y.E. (2004), "Bearing capacity of strip foundations with structural skirt", Geotech. Geol. Eng., 22(1), 43-57. https://doi.org/10.1023/B:GEGE.0000013997.79473.e0.
  2. Al-Aghbari, M.Y. and Mohamedzein, Y.E. (2006), "Improving the performance of circular foundations using structural skirt", Ground Improvement, 10(3), 125-132. https://doi.org/10.1680/grim.2006.10.3.125.
  3. Alzabeebee, S. (2020), "Dynamic response and design of a skirted strip foundation subjected to vertical vibration", Geomech. Eng., 20(4), 345-358. https://doi.org/10.12989/gae.2020.20.4.345.
  4. Azzam, W.R. and Farouk, A. (2010), "Experimental and numerical studies of sand slopes loaded with skirted strip footing", Electron. J. Geotech. Eng., 15, 795-812.
  5. Bashir, K., Shukla, R.P. and Jakka, R.S. (2023). "Skirted footing for enhancing load carrying capacity", Proceedings of the Geo-Congress 2023, 554-563.
  6. Bienen, B., Gaudin, C., Cassidy, M. J., Rausch, L., Purwana, O. A. and Krisdani, H. (2012), "Numerical modelling of a hybrid skirted foundation under combined loading", Comput. Geotech., 45, 127-139. https://https://doi.org/10.1016/j.compgeo.2012.05.009.
  7. Bolton, M.D. and Lau, C.K. (1993), "Vertical bearing capacity factors for circular and strip footings on Mohr-Coulomb soil", Can. Geotech. J., 30(6), 1024-1033. https://doi.org/10.1139/t93-099.
  8. Bransby, M.F. and Randolph, M.F. (1997), "Finite element modelling of skirted strip footings subject to combined loadings", Proceedings of the 7th International Offshore and Polar Engineering Conference.
  9. Bransby, M.F. and Yun, G.J. (2009), "The undrained capacity of skirted strip foundations under combined loading", Geotechnique, 59(2), 115-125. https://doi.org/10.1680/geot.2007.00098.
  10. Byrne, B., Houlsby, G., Martin, C. and Fish, P. (2002), "Suction caisson foundations for offshore wind turbines", Wind Eng., 26(3), 145-155. https://doi.org/10.1260/030952402762056063.
  11. Cascone, E. and Casablanca, O. (2016), "Static and seismic bearing capacity of shallow strip footings", Soil Dyn. Earthq. Eng., 84, 204-223. https://doi.org/10.1016/j.soildyn.2016.02.010.
  12. Chakraborty, D. and Kumar, J. (2013), "Bearing capacity of foundations on slopes", Geomech. Geoeng., 8(4), 274-285. https://doi.org/10.1080/17486025.2013.770172.
  13. Chen, W. and Randolph, M.F. (2007), "External radial stress changes and axial capacity for suction caissons in soft clay", Geotechnique, 57(6), 499-511. https://doi.org/10.1680/geot.2007.57.6.499.
  14. Chen, X.M., Cen, S., Long, Y.Q. and Yao, Z.H. (2004), "Membrane elements insensitive to distortion using the quadrilateral area coordinate method", Comput. Struct., 82, 35-54. https://doi.org/10.1016/j.compstruc.2003.08.004.
  15. Drescher, A. and Detournay, E. (1993), "Limit load in translational failure mechanisms for associative and non-associative materials", Geotechnique, 43(3), 443-456. https://doi.org/10.1680/geot.1993.43.3.443
  16. Ebid, A.M., Onyelowe, K.C. and Arinze, E.E. (2021). "Estimating the ultimate bearing capacity for strip footing near and within slopes using AI (GP, ANN, and EPR) techniques", J. Eng., 1-11.
  17. Eid, H.T. (2013), "Bearing capacity and settlement of skirted shallow foundations on sand", Int. J. Geomech., 13(5), 645-652. https://doi.org/10.1061/(ASCE)GM.1943-5622.0000237.
  18. Gerven, F.V. (2011), "Optimising the design of a flexible substructure for offshore wind turbines in deeper waters", MSc thesis, Faculty of Civil Engineering and Geosciences, Delft University of Technology, Netherlands.
  19. Golmoghani-Ebrahimi, S. and Rowshanzamir, M.A. (2013), "Experimental evaluation of bearing capacity of skirted footings", Civil Eng. Architect., 1(4), 103-108.
  20. Hjiaj, M., Lyamin, A.V. and Sloan, S.W. (2005), "Numerical limit analysis solutions for the bearing capacity factor Nγ", Int. J. Solid. Struct., 42(5-6), 1681-1704. https://doi.org/10.1016/j.ijsolstr.2004.08.002
  21. Hu, Y., Randolph, M.F. and Watson, P.G. (1999), "Bearing response of skirted foundation on nonhomogeneous soil", J Geotech. Geoenviron., 125(11), 924-935. https://doi.org/10.1061/(ASCE)1090-0241(1999)125:11(924).
  22. Juvekar, M.S. and Pise, P.J. (2008), "Behavior of rigid batter piles and pile groups subjected to horizontal load in sand", Indian Geotech. J., 38(2), 221-242.
  23. Keawsawasvong, S. and Ukritchon, B. (2016), "Finite element limit analysis of pullout capacity of planar caissons in clay", Comput. Geotech., 75, 12-17. https://doi.org/10.1016/j.compgeo.2016.01.015.
  24. Kellezi, L., Kudsk, G. and Hofstede, H. (2008), "Skirted footings capacity for combined loads and layered soil conditions", Proceedings of the BGA International Conference on Foundations, Dundee, Scotland, 24-27 June 2008.
  25. Khatri, V.N., Debbarma, S.P., Dutta, R.K. and Mohanty, B. (2017), "Pressure-settlement behavior of square and rectangular skirted footings resting on sand", Geomech. Eng., 12(4), 689-705. https://doi.org/10.12989/gae.2017.12.4.689.
  26. Krabbenhoft, K., Lyamin, A.V. and Krabbenhoft, J. (2015), Optum computational engineering.
  27. Krabbenhoft, K., Lyamin, A.V. and Sloan, S.W. (2007), "Formulation and solution of some plasticity problems as conic programs", Int. J. Solids Struct., 44(5), 1533-1549. https://doi.org/10.1016/j.ijsolstr.2006.06.036.
  28. Krabbenhoft, K., Lyamin, A.V. and Sloan, S.W. (2008), "Three-dimensional Mohr-Coulomb limit analysis using semidefinite programming", Numer. Method. Eng., 24(11), 1107-1119. https://doi.org/10.1002/cnm.1018.
  29. Kumar, J. (2003), "Nγ for rough strip footing using the method of characteristics", Can. Geotech. J., 40(3), 669-674. https://doi.org/10.1139/t03-009.
  30. Kumar, J. and Khatri, V. (2008), "Effect of footing roughness on lower bound Nγ values", Int. J. Geomech. ASCE, 8(3), 176-187. https://doi.org/10.1061/(ASCE)1532-3641(2008)8:3(176).
  31. Liew, K.M., Rajendran, S. and Wang, J. (2006), "A quadratic plane triangular element immune to quadratic mesh distortions under quadratic displacement fields", Comput. Method. Appl. Mech. Eng., 195(9-12), 1207-1223. https://doi.org/10.1016/j.cma.2005.04.012.
  32. Lyamin, A.V., Salgado, R., Sloan, S.W. and Prezzi, M. (2007), "Two and three-dimensional bearing capacity of footings in sand", Geotechnique, 57(8), 647-662. https://doi.org/10.1680/geot.2007.57.8.647.
  33. Lyamin, A.V., Sloan, S.W., Krabbenhoft, K. and Hjiaj, M. (2005), "Lower bound limit analysis with adaptive remeshing", Int. J. Numer. Method. Eng., 63(14), 1961-1974. https://doi.org/10.1002/nme.2421.
  34. Makrodimopoulos, A. and Martin, C.M. (2006), "Lower bound limit analysis of cohesive-frictional materials using second-order cone programming", Int. J. Numer. Method. Eng., 66(4), 604-634. https://doi.org/10.1002/nme.1567.
  35. Makrodimopoulos, A. and Martin, C.M. (2007), "Upper bound limit analysis using simplex strain elements and second-order cone programming", Int. J. Numer. Anal. Method. Geomech., 31(6), 835-865. https://doi.org/10.1002/nag.567.
  36. Mana, D.S., Gourvenec, S.M. and Randolph, M.F. (2013), "Experimental investigation of reverse end bearing of offshore shallow foundations", Can. Geotech. J., 50(10), 1022-1033. https://doi.org/10.1139/cgj-2012-0428.
  37. Mana, D.S., Gourvenec, S.M. and Randolph, M.F. (2014), "Numerical modelling of seepage beneath skirted foundations subjected to vertical uplift", Comput. Geotech., 55, 150-157. https://doi.org/10.1016/j.compgeo.2013.08.007.
  38. Mana, D.S., Gourvenec, S.M., Randolph, M.F. and Hossain, M.S. (2012), "Failure mechanisms of skirted foundations in uplift and compression", Int. J. Phys. Model. Geotech., 12(2), 47-62. https://doi.org/10.1680/ijpmg.11.00007.
  39. Martin, C.M. (2005), "Exact bearing capacity calculations using the method of characteristics", Proc. IACMAG. Turin, 441-450. 
  40. Meyerhof, G.G. (1965), "Shallow foundations", J. Soil Mech. Found.Division, American Society of Civil Engineers, 91(2), 21-31. https://doi.org/10.1061/JSFEAQ.0000719
  41. Michalowski, R.L. (1997), "An estimate of the influence of soil weight on bearing capacity using limit analysis", Soils Found. 37(4), 57-64. https://doi.org/10.3208/sandf.37.4_57.
  42. Nazir, A.K. and Azzam, W.R. (2010), "Improving the bearing capacity of footing on soft clay with sand pile with/without skirt", Alexandria Eng. J., 49(4), 371-377. https://doi.org/10.1016/j.aej.2010.06.002.
  43. Optum G2 https://optumce.com/products/optumg2/
  44. Park, J.S., Park, D. and Yoo, J.K. (2016), "Vertical bearing capacity of bucket foundations in sand", Ocean Eng., 121, 453-461. https://doi.org/10.1016/j.oceaneng.2016.05.056.
  45. Pula, W. and Chwala, M. (2018), "Random bearing capacity evaluation of shallow foundations for asymmetrical failure mechanisms with spatial averaging and inclusion of soil selfweight", Comput. Geotech., 101, 176-195. https://doi.org/10.1016/j.compgeo.2018.05.002.
  46. Sajjad, G. and Masoud, M. (2018), "Study of the behaviour of skirted shallow foundations resting on sand", Int. J. Phys. Model. Geotech., 18(3), 117-130. https://doi.org/10.1680/jphmg.16.00079.
  47. Saleh, N.M., Alsaied, A.E. and Elleboudy, A.M. (2008), "Performance of skirted strip footing subjected to eccentric inclined load", Electron. J. Geotech. Eng., 13, 1-33.
  48. Selmi, M., Kormi, T., Hentati, A. and Ali, N.B.H. (2019), "Capacity assessment of offshore skirted foundations under HM combined loading using RFEM", Comput. Geotech., 114, 103148. https://doi.org/10.1016/j.compgeo.2019.103148.
  49. Seo, M.J., Han, K., Park, J.B., Jeong, K.H. and Lee, J.S. (2021), "End bearing capacity of embedded pile with inclined base plate: Field dynamic and static tests", Geomech. Eng., 26(3), 261-274. https://doi.org/10.12989/gae.2021.26.3.261.
  50. Shukla, R.P. (2019), "Bearing capacity of skirted footing on slopes", Ph.D. Dissertation, Indian Institute of Technology Roorkee, Roorkee.
  51. Shukla, R.P. (2022), "Bearing capacity of skirted footing subjected to inclined loading", Mag. Civil Eng.. 110(2), https://doi.org/11012. 10.34910/MCE.110.12.
  52. Shukla, R.P. and Jakka, R.S. (2022), "Bearing capacity and failure mechanism of skirted footings", Geomech. Eng., 30(1), https://doi.org/10.12989/gae.2022.30.1.051.
  53. Shukla, R.P. and Jakka, R.S. (2018), "Critical setback distance for a footing resting on slopes under seismic loading", Geomech. Eng., 15(6), 1193-1205. https://doi.org/10.12989/gae.2018.15.6.1193.
  54. Tani, K. and Craig, W.H. (1995), "Bearing capacity of circular foundations on soft clay of strength increasing with depth", Soils Found., 35(4), 21-35. https://doi.org/10.3208/sandf.35.4_21.
  55. Terzaghi, K. (1943), "Theoretical soil mechanics", Wiley, New York.
  56. Ukritchon, B. and Keawsawasvong, S. (2016), "Undrained pullout capacity of cylindrical suction caissons by finite element limit analysis", Comput. Geotech., 80, 301-311. https://doi.org/10.1016/j.compgeo.2016.08.019.
  57. Ukritchon, B., Whittle, A. and Klangvijit. C. (2003), "Calculations of bearing capacity factor Nγ using numerical limit analyses", J. Geotech. Geoenviron. Eng., 129(5), 468-474. https://doi.org/10.1016/j.ijsolstr.2004.08.002
  58. Valore, C., Ziccarelli, M. and Muscolino, S.R. (2017), "The bearing capacity of footings on sand with a weak layer", Geotech. Res., 4(1), 12-29. https://doi.org/10.1680/jgere.16.00020.
  59. Vulpe, C., Gourvenec, S.M. and Cornelius, A.F. (2016), "Effect of embedment on consolidated undrained capacity of skirted circular foundations in soft clay under planar loading", Can. Geotech. J., 54(2), 158-172. https://doi.org/10.1139/cgj-2016-0265.
  60. Wakil, E.A.Z. (2013), "Bearing capacity of skirt circular footing on sand", Alexandria Eng. J., 52(3), 359-364. https://doi.org/10.1016/j.aej.2013.01.007.
  61. Yan, Z., Liu, R.L., Lv, P. and Zhang, H.Q. (2020), "Model tests on jacking installation and lateral loading performance of a new skirted foundation in sand", Ocean Eng., 197, 106914. https://doi.org/10.1016/j.oceaneng.2019.106914.
  62. Yin, J.H., Wang, Y.J. and Selvadurai, A.P.S. (2001), "Influence of nonassociativity on the bearing capacity of a strip footing", J. Geotech. Geoenviron. Eng., 127(11), 985-989. https://doi.org/10.1061/(ASCE)1090-241(2001)127:11(985).
  63. Yun, G.J. and Bransby, M.F. (2007), "The undrained vertical bearing capacity of skirted foundations", Soils Found., 47(3), 493-505. https://doi.org/10.3208/sandf.47.493.
  64. Zhang, L., McVay, M.C. and Lai, P.W. (1999), "Centrifuge modelling of laterally loaded single battered piles in sand", Can. Geotech. J., 36(6), 1074-1084. https://doi.org/10.1139/t99-072.
  65. Zhang, P. and Ding, H. (2011), "Bearing capacity of the bucket spudcan foundation for offshore jack-up drilling platforms", Petroleum Exploration and Development, 38(2), 237-242. https://doi.org/10.1016/S1876-3804(11)60029-3.
  66. Zhu, D. (2000), "The least upper-bound solutions for bearing capacity factor Nγ", Soils Found. 40(1), 123-129. https://doi.org/10.3208/sandf.40.123.
  67. Ziccarelli, M., Valore, C., Muscolino, S.R. and Fioravante, V. (2017), "Centrifuge tests on strip footings on sand with a weak layer", Geotech. Res., 4(1), 47-64. https://doi.org/10.1680/jgere.16.00021.