Evaluation of the Thin Layer Effect on the Ultimate Bearing Capacity of Strip Foundation on Sand

Document Type : Research Article


1 Department of Civil Engineering, Hamedan Branch, Islamic Azad University, hamedan, Iran

2 Civil Engineering Department, Science and Research Branch, Islamic Azad University, Tehran, Iran

3 Assistant Professor, Civil Engineering Department, Faculty of Engineering, Bu-Ali Sina University, Hamedan, Iran

4 Assistant Professor of Science and Research branch of Azad university


Shallow foundations, such as strip foundations are widely used in transmitting loads from the superstructure to the supporting soils. In many cases, the ground materials are not uniform and may have thin layers, which are not usually detected in geotechnical site investigations. In this research, the effects of a thin layer on the ultimate bearing capacity of a strip foundation on the sand bed are investigated by small-scale physical models. Due to very limited research that has been carried out on the thin layer effect on the ultimate bearing capacity, it seems that further studies can understand the effect of this layer. The investigations were carried out by varying the material type, thickness, and depth of the thin layer. The results indicate that the weak thin layer decreases both the ultimate bearing capacity and stiffness of the soil-foundation system and the strong thin layer increases both the ultimate bearing capacity and the soil-foundation system stiffness. The amount of this effect depends on the thickness, depth of deposition, and material type of the thin layer. According to the results, the weak layer for the critical depth of 1.2B led to the most reduction in ultimate bearing capacity by 40%, while no effects were observed at a depth of 3.6B. The strong layer is also for the state where this layer is just below the footing, had the highest increase in ultimate bearing capacity by 76%, but at a depth of about 2.4B, it was ineffective.


Main Subjects

[1] C. Valore, M. Ziccarelli, S.R. Muscolino, The bearing capacity of footings on sand with a weak layer, Geotechnical Research, 4(1) (2017) 12-29.
[2] K. Terzaghi, Effect of minor geologic details on the safety of dams, Amer. Inst. Min. and Met. Engrs. Tech. Publ., 215 (1929) 31-44.
[3] K.v. Terzaghi, The shearing resistance of saturated soils and the angle between the planes of shear, in:  First international conference on soil Mechanics, 1936, 1936, pp. 54-59.
[4] A. Gupta, R.K. Dutta, R. Shrivastava, V.N. Khatri, Ultimate bearing capacity of square/rectangular footing on layered soil, Indian Geotechnical Journal, 47(3) (2017) 303-313.
[5] M. Haghbin, Bearing capacity of strip footings resting on granular soil overlying soft clay, International Journal of Civil Engineering, 14(7) (2016) 467-477.
[6] K.M.H. Ismail Ibrahim, Bearing capacity of circular footing resting on granular soil overlying soft clay, HBRC journal, 12(1) (2016) 71-77.
[7] E. Uncuoglu, The bearing capacity of square footings on a sand layer overlying clay, Geomechanics and Engineering, 9(3) (2015) 287-311.
[8] P. Maheshwari, M. Viladkar, Strip footings on a three layer soil system: theory of elasticity approach, International Journal of Geotechnical Engineering, 1(1) (2007) 47-59.
[9] M. Ziccarelli, C. Valore, S.R. Muscolino, V. Fioravante, Centrifuge tests on strip footings on sand with a weak layer, Geotechnical Research, 4(1) (2017) 47-64.
[10] M. Oda, S. Win, Ultimate bearing capacity tests on sand with clay layer, Journal of Geotechnical Engineering, 116(12) (1990) 1902-1906.
[11] M. Askari, A.B. Khalkhali, M. Makarchian, N. Ganjian, The bearing capacity of circular footings on sand with thin layer: An experimental study, Geomechanics and Engineering, 27(2) (2021) 123-130.
[12] H.G. Poulos, Pile behavior—Consequences of geological and construction imperfections, Journal of geotechnical and geoenvironmental engineering, 131(5) (2005) 538-563.
[13] V. Murthy, 12 of of K of, in:  Geotechnical Engineering, CRC Press, 2002, pp. 409-409.
[14] D. ASTM, 4253-00, 2006, Standard test methods for maximum index density and unit weight of soils using a vibratory table. ASTM International, West Conshohocken, PA, USA.
[15] D. ASTM, Standard test methods for minimum index density and unit weight of soils and calculation of relative density, in, West Conshohocken PA., 2006.
[16] M. Bolton, C. Lau, Scale effects in the bearing capacity of granular soils, in:  Congrès international de mécanique des sols et des travaux de fondations. 12, 1989, pp. 895-898.
[17] R. Taylor, Centrifuges in modelling: principles and scale effects, in:  Geotechnical centrifuge technology, CRC Press, 2018, pp. 19-33.
[18] Y. Toyosawa, K. Itoh, N. Kikkawa, J.-J. Yang, F. Liu, Influence of model footing diameter and embedded depth on particle size effect in centrifugal bearing capacity tests, Soils and foundations, 53(2) (2013) 349-356.
[19] C. Martin, Exact bearing capacity calculations using the method of characteristics, Proc. IACMAG. Turin,  (2005) 441-450.
[20] G.G. Meyerhof, Some recent research on the bearing capacity of foundations, Canadian geotechnical journal, 1(1) (1963) 16-26.
[21] A.S. Vesić, Analysis of ultimate loads of shallow foundations, Journal of the Soil Mechanics and Foundations Division, 99(1) (1973) 45-73.
[22] B. Bodo, C. Jones, Introduction to soil mechanics, John Wiley & Sons, 2013.