Load-Settlement Behaviour of Model Pile Groups in Sand Under Vertical Load

Abstract

Model pile load testing is effective to study the load-settlement behaviour of pile foundations given the con­trolled environment in which the testing is done. This paper reports a testing program in a large calibration chamber involving individual piles and pile groups installed in sand samples of three different densities. Tests on both nondis­placement and driven piles are evaluated to assess the influence of the pile installation process on pile load-settlement response. A method is proposed to predict the load-settlement response of a pile group based on the response of a single pile. The method is shown to produce estimates that are in good agreement with measurements. The influence of pile group configuration, pile spacing, soil density and method of pile installation is discussed.

Experimental Study on Bearing Resistance of Short Displacement Pile Groups in Dense Sands

“…The stiffness of an individual pile in the DPG with a = 2D differed by up to 154%. This result conflicts with the findings by Sales et al (2017), stating the installation effects as negligible. From a practical point of view, this phenomenon might cause a rotation of the supported structure, consequently inducing additional internal forces, which should lead to the underestimation of the structure's stiffness and bearing capacity.…”

“…The DPG efficiency factor η for loading up to < 0.1 s D is in good agreement with the predictions by Vesic (1967Vesic ( , 1968 and Tejchman (1973) but is in conflict with the results determined by Broms (1981), Kishida (1964), Choi et al (2017), Sales et al (2017), Gowthaman and Nasvi (2018), Sharma et al (2019), yielding η < 1. Tests determined an increase of η when decreasing the spacing a in dense sands, and this result conflicts with the results reported by Gogoi et al (2014) and Gowthaman and Nasvi (2018).…”

“…He stated that η was slightly less than 1 for the PG driven in dense sand, while η > 1 for the PG driven in medium dense and loose sand. Sales et al (2017) tested PGs in sands of various densities. According to their findings, (1) the spacing a in sand has minimal effect when a/D > 4; (2) η > 1 is for loose to medium dense sand, while η < 1 in dense sand; and (3) the driving effects of SPs had an impact on the load-settlement response of PGs with spacings a = 2D, 3D, whereas for a = 4D, installation effects were negligible.…”

Experimental Investigation on Efficiency Factor of Pile Groups Regarding Distance of Piles

“…Therefore the coefficient efficiency is smaller than 1.The efficiency of pile groups is more than single pile and this increase maximizes at closer distances. These results are similar to the results which previous researchers have achieved such as Vesić (1969) [3], Sales et al (2017) [19], Lee and Chung (2005) [17]. In groups with distance of 3d, piles have interaction to each other.…”

“…In addition, the materials used in this method like bentonite intensify the looseness. These two methods of installation have different effects on interaction factor [19][20]. In these experiments, none of these conditions was exactly dominated since piles initially were set.…”