Behaviour of single batter piles and pile groups under lateral soil movement in sand

Al-Salih, OSA

Abstract

Piles are commonly subjected to induced loads from nearby construction activities such as approach embankments, excavation, tunnelling and moving slopes. To better understand the mechanism of this complicated soil-pile interaction problem, a comprehensive experimental and numerical program were carried out to investigate the behaviour of batter pile foundations embedded in sandy soil when subjected to lateral soil movements.

In the experimental work, a series of model tests on single batter pile subjected to a soil movement profile (triangular or rectangular) was performed to study the effect of a number of parameters on the behaviour of single batter pile. In addition, the lateral responses were investigated on a group of batter piles of different configurations: Batter-Vertical (VB), Vertical-Batter (VB), Both Vertical (VV) and Both Batter (BB). The effect of centre to centre pile spacing (S) was also investigated. The results from the single pile tests show that, the maximum bending moment induced in a single batter pile was found to be dependent on, among other factors, batter angle, pile embedded length, distance between the batter piles location and soil movement source, pile diameter, profile of soil movement, sand density and the pile head fixity condition. Regardless of the value of batter angle, the bending moment profile was a single curvature. The largest value of maximum bending moment was observed for the negative batter pile while vertical pile results showed lower value, however, the lowest value was recorded for the positive batter pile. For the pile group tests; the behaviour of the individual piles in a group are significantly affected by the pile spacing, pile head conditions and the pile group arrangement. It was also shown that the group effect might either increase or decrease the maximum bending moment, depending on the above-mentioned influencing factors.

Numerical analyses with the three-dimensional finite element method were performed using PLAXIS 3D software with "embedded pile" feature to predict and compare the results from the single batter piles and pile groups tests in sand. In all the predictions, the numerical analysis was shown to be able to predict the experimental results reasonably well. Result of parametric studies indicated that Young’s modulus and friction angle were among the parameters that had the greater effect on batter pile behaviour, in particular the lateral displacement and bending moments of piles. Other less influential parameters were the interface properties between the pile and the soil, dilation angle, the density of finite element mesh and the pile cross-sectional shapes.

In summary, through the numerical and experimental outcomes, it is hoped that the current study provides an important understanding and clear indications of how both soil and pile parameters are affecting the behaviour of batter pile and batter pile groups subjected to lateral soil movements.

Citation

Al-Salih, O. (in press). Behaviour of single batter piles and pile groups under lateral soil movement in sand. (Thesis). University of Salford

• Thesis Type: Thesis
• Acceptance Date: Apr 30, 2019
• Deposit Date: May 7, 2019
• Publicly Available Date: Oct 30, 2019
• Additional Information: Funders : Iraqi Government