Document Type : Research Paper

Authors

Civil Engineering Dept., University of Technology-Iraq, Alsina’a street, 10066 Baghdad, Iraq.

Abstract

Skirted foundations are one of the solutions proposed to increase the bearing capacity of the soil. They assist in increasing the load and depth of failure in weak ground or soils with low shear resistance and reducing the foundation settlement if a soil improvement method cannot be applied or the cost of implementing deep foundations increases. This study examined and investigated the extent of soil bearing of skirted foundations on sandy soils and studied the effect of soil saturation cases and three cases of water content reduction to measure the matric suction value of unsaturated soil. A physical model was created to simulate the strip foundation and compare these cases (dry-fully saturated-partially saturated). It was found that the soil load carrying capacity in the case of unsaturated soil is the highest, where matric suction is at a depth of 450 mm, followed by the dry case and then the saturated case as it represents the weakest state of the soil.

Graphical Abstract

Highlights

  • The soil load carrying capacity in the case of unsaturated soil is the highest.
  •  A structural skirt increases the bearing capacity, reduces the settlement, and modifies the load settlement behavior of the footing.
  • A significant decrease in the load-carrying capacity was observed as the soil below the base of the foundation gets fully saturated.

Keywords

Main Subjects

[1] B. W. Byrne, F.Villalobos, , G. T. Houlsby, and C. M Martin, Laboratory testing of shallow skirted foundations in sand, In Proc. British Geotechnical Association Int. Conf. on Foundations, Dundee, 2 (2002) 161-173.
[2] G. J.Yun, and M. F, Brans by, Centrifuge modeling of the horizontal capacity of skirted foundations on drained loose sand, In BGA International Conference on Foundations: Innovations, observations, design, and practice: Proceedings of the international conference organized by British Geotechnical Association and held in Dundee, pp. 975-984. Thomas Telford Publishing, Scotland on 2–5th September (2003).
[3] M.  El Sawwaf, and A.Nazer, Behavior of circular footings resting on confined granular soil, J. Geotech. Geoenviron. Eng., ASCE, 131 (2005) 359-366.
[4] F. Villalobos, bearing capacity of skirted foundations in sand. In VI Congress Chile no de Geotechnical (pp. 1-14). Valparaiso, (2007).
[5] El-Wakil, Z. Amr, Horizontal capacity of skirted circular shallow footings on sand. Alexandria Engineering Journal 49 (2010) 379-385.
[6] S. Tripathy, Load carrying capacity of skirted foundation on sand, M.Sc. thesis, Civil engineering department, National Institute of Technology, Rourkela,( 2013).
[7] T.Eid, Hisham Bearing capacity and settlement of skirted shallow foundations on sand. International Journal of Aeromechanics 13 (2013) 645-652.
[8] A. Krishna, B.Viswanath, and Nikita Keshav. Performance of square footing resting on laterally confined sand. Int J Res Eng. Technol.  J., 3 (2014) 110-114.
[9] E. Momeni, R. Nazir, D.J. Armaghani, H. Sohaie. Bearing capacity of precast thin-walled foundation in sand Proceedings of the Institution of Civil Engineers-Geotechnical Engineering. Dec; 168(6):539-50, (2015).
[10] S. W Thakare, and A. N. Shukla. Performance of rectangular skirted footing resting on sand bed subjected to lateral load. International Journal of Innovative Research in Science, Eng. Technol.  J., 5 (2016) 11075-11083.
[11] V.N.  Khatri, S.P.Debbarma, R.K. Dutta, and B.Mohanty, Pressure-settlement behavior of square and rectangular skirted footings resting on sand. Aeromechanics and Engineering, 12 (2017).689-705.
[12] M. R.Mahmood Improvement ratio and behavior of bearing capacity factors for strip skirt footing model resting on sand of different grain size distribution. In MATEC Web of Conferences .62 (2018) 01026, EDP Sciences.
[13] G. Sajjad, and M.Masoud, Study of the behaviour of skirted shallow foundations resting on sand. International Journal of Physical Modelling in Geotechnics, 18 (2018) 117-130.
[14] A. Vijay, , V. Akella, and B.R. Prasad, Experimental Studies and Numerical Validation on Bearing Capacity of Skirted Footings on c-Φ Soils. In Advances in Structures, Systems and Materials (pp. 85-98). Springer, Singapore, (2020).
[15] S. Alzabeebee, Dynamic response and design of a skirted strip foundation subjected to vertical vibration. Genomic Eng., 20 (2020)345-358.
[16] M.Y Al-Aghbari, and Y.E.A.Mohamedzein, The use of skirts to improve the performance of a footing in sand. Int. J. Geotech. Eng., 14 (2020) 134-141.
[17] ASTM, D422, Standard test method for particle size analysis of soil, American Society of Testing and Materials. (2000).
[18] ASTM, D 854-00, Standard test method for specific gravity of soil solids by water pycnometer. Annual book of ASTM standard, (2000).
[19] ASTM, D 4253. Standard Test Methods for Maximum Index Density and Unit Weight of Soils Using a Vibratory Table. ASTM International, (2000).
[20] ASTM, D4254 Standard test methods for minimum index density and unit weight of soils and calculation of relative density, (2006).