Effect of Pile Spacing on Group Efficiency in Gypseous Soil

Bilal Jabbar Noman, Safaa H. Abd-Awn, Hassan O. Abbas


As a matter of fact, the gypseous soil is usually considered as collapsible soil, such type of soil illustrates high resistance to settlement and high bearing capacity when it is dry, but it loses these characteristics when it is inundated and collapses excessively because of the sudden decrease in the volume of the surrounding soil mass. It is founded in the arid and semi-arid regions of the world in Asia, South Asia (Iraq, Syria, Jordan, Yemen, and Iran), North Africa, North America, moreover, it covers more than (31%) of the surface area in Iraq. Gypseous soil is one of the most difficult problems facing the process of building any project because of the difficulty of preventing leakage of water to the soil in practice. Deep foundation (piles) are one of the most common types used in collapsible soils which penetrating problematic soil layers and reaching more hard ones (end bearing piles) or transfers loads depending on skin friction (floating pile). The current work is directed to study the behavior of single and group driven pile of square pattern (4 piles) in case of floating pile (friction pile) with different spacing (2D, 4D, 6D) and length to diameter (L/D) ratio of (20) in this special medium dense soil (gypsum content 30% and 61%) under axial load condition. The investigation was carried out to measure the soil collapse before and after inundation. The results showed that the group efficiency for spacing 2D is less than one while for spacing 4D and 6D are more than that value. In addition, the spacing 4D was more efficient to carry 4 group pile in both dry and soaked cases, in addition, the result showed a high reduction in the bearing capacity at inundation state of group pile of (82% in gypsum content 30%) and ( 87% in gypsum content 61%) with respect to dry state.


Gypseous Soil; Pile Spacing; Group Efficiency; Axial Load; Driven Pile.


Mitchell, James Kenneth, and Kenichi Soga. Fundamentals of soil behavior. Vol. 3. New York: John Wiley & Sons, 2005.

Pereira, Jose HF, and Delwyn G. Fredlund. "Volume change behavior of collapsible compacted gneiss soil." Journal of geotechnical and geoenvironmental engineering 126, no. 10 (2000): 907-916. doi: 10.1061/(asce)1090-0241(2002)128:2(183).

Abdrabbo, F. M., and T. M. Abdelaziz. "Study of the infiltration of water through collapsible soil." In Unsaturated Soils 2006, pp. 1049-1060. 2006. doi: 10.1061/40802(189)85.

Futai, M. M., M. S. S. Almeida, and W. A. Lacerda. "The shear strength of unsaturated tropical soils in Ouro Preto, Brazil." In Unsaturated Soils 2006, pp. 1200-1211. 2006. doi: 10.1061/40802(189)98.

Dudley, John H. "Review of collapsing soils." Journal of the Soil Mechanics and Foundations Division 96, no. 3 (1970): 925-947.

Barden, Ll, A. McGown, and K. Collins. "The collapse mechanism in partly saturated soil." Engineering Geology 7, no. 1 (1973): 49-60.doi: 10.1016/0013-7952(73)90006-9.

Razouki, S. S., R. R. Al-Omari, I. H. Nashat, H. F. Razouki, and S. Khalid. "The problem of gypsiferous soils in Iraq." In Proceeding of the Symposium on Gypsiferous Soils and Their Effect on Structures, NCCL, pp. 7-33. 1994.

Nashat, I. H. "Engineering characteristics of some gypseous soils in Iraq." Unpub. Ph. D. Thesis. University of Baghdad (1990).

Al-Busoda, Bushra Suhale, and Asmaa Hasan Al-Rubaye. "Bearing Capacity of Bored Pile Model Constructed in Gypseous Soil." Journal of Engineering 21, no. 3 (2015): 109-128.

Arutyunyan, R. N. "Deformations of gypsofied soils in the bases of building and structures in Erevan." Soil Mechanics and Foundation Engineering 15, no. 3 (1978): 183-185. doi: 10.1007/bf02132797.

Bowles, L. E. (1996), “Foundation Analysis and Design, Fifth Edition”. McGraw-Hill.

Fang, H.Y., “Foundation engineering handbook”. Springer Science & Business Media, 2013.

Lee, C. J., M. D. Bolton, and A. Al-Tabbaa. "Numerical modelling of group effects on the distribution of dragloads in pile foundations." Geotechnique 52, no. 5 (2002): 325-335. doi: 10.1680/geot.52.5.325.38704.

Prakash, S. and Sharma, H.D. “Pile foundations in engineering practice”. John Wiley & Sons, 1990.

Murthy, V. N. S. "Advanced Foundations Engineering-Geotechnical Engineering Series." CBS Publisher & Distributors, New Delhi (2007): 251-534.

Al-Mufty, A. A., and I. H. Nashat. "Gypsum content determination in gypseous soils and rocks." In Proceedings of the 3th Jordanian international mining conference, Amman, vol. 2, pp. 485-492. 2000.

Kishida, Hideaki. "Stress distribution by model piles in sand." Soils and Foundations 4, no. 1 (1963): 1-23. doi: 10.3208/sandf1960.4.1.

Robinsky, E. I., W. L. Sagar, and C. F. Morrison. "Effect of shape and volume on the capacity of model piles in sand." Canadian Geotechnical Journal 1, no. 4 (1964): 189-204.doi: 10.1139/t64-015.

Comodromos, , Emilios M., Christos T. Anagnostopoulos, and Michael K. Georgiadis. "Numerical assessment of axial pile group response based on load test." Computers and Geotechnics 30, no. 6 (2003): 505-515.doi: 10.1016/s0266-352x(03)00017-x.

Lee, Su-Hyung, and Choong-Ki Chung. "An experimental study of the interaction of vertically loaded pile groups in sand." Canadian Geotechnical Journal 42, no. 5 (2005): 1485-1493. doi: 10.1139/t05-068.

Gogoi, Nihar, Sanandam Bordoloi, and Binu Sharma. "A Model Study of Micropile Group Efficiency under Axial Loading Condition." International Journal of Civil Engineering Research. ISSN: 2278-3652, 2014.

Zhang, Qian-qing, Shi-min Zhang, Fa-yun Liang, Qian Zhang, and Fei Xu. "Some observations of the influence factors on the response of pile groups." KSCE Journal of Civil Engineering 19, no. 6 (2015): 1667-1674.doi: 10.1007/s12205-014-1550-7.

Tehrani, Faraz S., Rodrigo Salgado, and Monica Prezzi. "Analysis of axial loading of pile groups in multilayered elastic soil." International Journal of Geomechanics 16, no. 2 (2015): 04015063.doi: 10.1061/(asce)gm.1943-5622.0000540.

Tuan. “A Simplified Formular For AnalysisGroup Efficiency of Piles in Granular Soil”. International Journal of Scientific & Engineering Research, 7(7), 2016.

Choi, Yoon Seok, Jintae Lee, Monica Prezzi, and Rodrigo Salgado. "Response of pile groups driven in sand subjected to combined loads." Geotechnical and Geological Engineering 35, no. 4 (2017): 1587-1604.doi: 10.1007/s10706-017-0194-z.

Sales, Mauricio Martines, Monica Prezzi, Rodrigo Salgado, Yoon Seok Choi, and Jintae Lee. "Load-settlement behaviour of model pile groups in sand under vertical load." Journal of Civil Engineering and Management 23, no. 8 (2017): 1148-1163. doi: 10.3846/13923730.2017.1396559.

Gowthaman, S., and M. C. M. Nasvi. "Three-dimensional Numerical Simulation and Validation of Load-settlement Behaviour of a Pile Group under Compressive Loading." ENGINEER 51, no. 01 (2018): 9-21. doi: 10.4038/engineer.v51i1.7283.

Sharma, Binu, Sushanta Sarkar, and Zakir Hussain. "A Study of Parameters Influencing Efficiency of Micropile Groups." In Ground Improvement Techniques and Geosynthetics, pp. 11-18. Springer, Singapore, 2019.doi: 10.1007/978-981-13-0559-7_2.

Aksoy, H.S., Gör, M. and İnal, E., “A new design chart for estimating friction angle between soil and pile materials”. Geomechanics and Engineering, 10(3), 2016, pp.315-324.

Aksoy, H.S., Gör, M. and İnal, E., “Determination of Friction Angles between Soil and Steel-FRP Piles”. Fırat University Turkish Journal of Science & Technology, 13(1), 2018, pp.19-23.

Schanz, Tom, and Hussein H. Karim. “Geotechnical Characteristics of Some Iraqi Gypseous Soils.” Edited by T.S. Al-Attar, M.A. Al-Neami, and W.S. AbdulSahib. MATEC Web of Conferences 162 (2018): 01005. doi:10.1051/matecconf/201816201005.

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DOI: 10.28991/cej-2019-03091252


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