Experimental and Statistical Study on Single and Groups of Stone Columns

Abstract:

In the present study, 24 laboratory models on soft clay treated with stone columns were carried out. The results for each case are analysed for the purpose of constructing a statistical model linking the variables studied. The experiments showed that the stress concentration and bearing capacity of soil treated with stone column increase with increasing the undrained shear strength (cu), number of columns and L/d ratio. The models represent a single stone column and a group of stone columns. The studied variables are three dependent variables, the stress concentration ratio (n), bearing capacity of soil treated with stone column (q) and the settlement improvement ratio (S_r) due to the existence of stone columns. The independent variables are six: the undrained shear strength of clay soil, with three values (6, 9 and 12 kPa), the number of stone columns (1, 2, 3 and 4 columns) and the length (L) to the diameter (D) of the stone column or (L/D) ratio in two values (6 and 8). Besides, the bearing capacity of the soil treated (q) with stone columns and the settlement improvement ratio were used in some statistical models as independents. After regression analysis, a set of equations that correlate the previous variables have been suggested. The incepted values for dependent variables are close to the laboratory results.

• Periodical: Key Engineering Materials (Volume 857)
• Pages: 399-408
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.857.399
• Online since: August 2020
• Authors: Maki J. Mohammed Al-Waily*, Mohammed Y. Fattah, Maysa Salem Al-Qaisi
• Keywords: Group, Laboratory, Single, Statistical Models, Stone Column

References

[1] Hughes, J. M. O., & Withers, N. J., Reinforcing of soft cohesive soils with stone columns, Ground engineering. Vol. 7, No. 3, (1974) 42 – 49.

[2] Madhav, M. R., and Vitkar, P. P, Strip footing on weak clay stabilized with a granular trench or pil, Can. Geotech. J.,15(4), (1978) 605–609.

DOI: 10.1139/t78-066

[3] Aboshi, H., Ichimoto, E., Enoki, M. & Harada, K., The compozer: a method to improve characteristics of soft clays by inclusion of large diameter sand columns, proceedings International Conference on soil reinforcement; Reinf. Earth and other techniques. Vol. 1, Paris, (1979) 211 – 216.

[4] Indian Standards (IS), Indian standard code of practice for de-sign and construction for ground improvement-guidelines. Part 1: Stone columns, IS 15284 (Part 1), New Delhi, India (2003).

[5] Greenwood, D. A., Mechanical improvement of soils below ground surface", Proceedings Ground Engineering Conference, Institution of Civil Engineers, (1970).

[6] Jellali, B., Bouassida, M., and De Buhan, P., A homogenization method for estimating the bearing capacity of soils reinforced by stone columns, Int. J. Numer. Analyt. Meth. Geomech. ,29(10), (2005) 989–1004.

DOI: 10.1002/nag.441

[7] Kempfert, H. G., Ground improvement methods with special emphasis on column-type techniques,, Int. Workshop on Geotechnics of Soft Soils (2003).

[8] Fattah, M. Y., Shlash, Kais T., Al-Waily, Maki J., Stress Concentration Ratio of Model Stone Columns in Soft Clays, Geotechnical Testing Journal, ASTM, Vol. 34, No. 1, (2003) 61-71, Paper ID GTJ103060Available online at: www.astm.org.

DOI: 10.1520/gtj103844

[9] Fattah, M. Y., Zabar, B. S., Hassan, H. A., Experimental Analysis of Embankment on Ordinary and Encased Stone Columns, International Journal of Geomechanics, ASCE, Vol. 16, No. 4 (2016), DOI 10.1061/(ASCE)GM.1943-5622.0000579 , 04015102.

DOI: 10.1061/(asce)gm.1943-5622.0000579

[10] Fattah, M. Y., Al-Neami, M. A., Al-Suhaily, A. S., Estimation of Bearing Capacity of Floating Group of Stone Columns, Engineering Science and Technology, an International Journal, Vol. 20, (2017) 1166–1172, http://dx.doi.org/10.1016/j.jestch.2017.03.005, Elsevier.

DOI: 10.1016/j.jestch.2017.03.005