Effect of Pile's Number on the Behavior of Piled Raft Foundation

Abstract

This paper introduces an experimental research on the behavior of the piled raft foundation (PRF) in sand of two states (loose and medium sand). A small model has been tested in a soil container and the vertical load was applied to the foundation through a pneumatic jack. The settlement of the foundation was measured using a displacement transducer; three sensors were attached to the pile heads to measure the axial load borne in a group by each pile by the Arduino data logger. The laboratory experiments were carried out on models of (1 pile), ( 1x2), ( 1x3), ( 2x3), (3 x3), (3 piles triangular), (4 piles diamond), (5 piles), and (9 pile circle), as well as to tests on an unpiled raft. Test variables were pile length, number of piles, and sand density. It is noticed that when the piles increased to nine piles in the group, the bearing capacity increased by 40%. The effect starts to increase when one pile is just placed under the raft as the bearing capacity of the piled raft increased by 3% and 7% when the pile length is 15D and, 20D, respectively. The reduction in the settlement is also observed to be smaller and no economic advantage is achieved with more increase in the number of piles. If the number of piles reaches (6) piles, the influence of the piled raft on settlement reduction disappears.

Influence of Plate Position on Uplift Failure State and Bearing Capacity of NT-CEP Pile Groups

“…Recently, theoretical and experimental investigations have been conducted on a single, leading to comprehensive research results [6,7]. However, little research has been done on NT-CEP pile groups by engineering practices [8][9][10][11][12]. In this study, the bearing capacity of the NT-CEP pile group and the failure state of the soil around the pile were studied theoretically.…”

Effects of disc overhang diameter on the uplift bearing capacity of new-type concrete expanded-plate pile groups

“…New-type concrete-expanded plate (NT-CEP) piles are variable-section grouting piles 1 – 3 with low construction costs, high bearing capacities, and small settlements 4 – 6 ,depicted in Figs. 1 and 2 .They are different from ordinary equal diameter piles, and the ultimate tensile bearing capacity of single plate piles is 178% higher than that of equal diameter piles.Their use in engineering is increasing 7 , 8 ; however, previous studies have mainly focused on single and double NT-CEP piles,with most studies conducted by the research group of this paper 9 – 11 and few have considered pile groups 12 , 13 . Therefore, a systematic investigation of NT-CEP pile groups is required.…”

Theoretical Analysis of the Influence of Bearing Plate Position on the Bearing Performance of Soil around the CEP Antipull Force Double Pile

“…Compared with ordinary concrete straight hole cast piles, CEP piles have increased the bearing plate at the pile body position, and the bearing plate can be set flexibly at the pile body position as well as each parameter of the bearing plate, which changes the force mechanism of the pile body, greatly increases the contact area between the pile and the soil body, and increases the end-bearing force, which greatly improves the bearing capacity and stability of the pile body. At present, the foundation research on single piles of CEP pile has become mature [5][6][7][8], but the foundation research on pile groups is mostly based on ordinary concrete straight-hole cast-in-place piles [9,10], and research on CEP pile groups is still in the blank stage [11]; it seriously affects the development and application of CEP piles. When the pile spacing is insufficient, adjacent piles will have a greater mutual influence due to the special pile shaft structure of a CEP pile [12,13].…”