A simplified analysis method for piled raft foundations in non‐homogeneous soils

Abstract

SUMMARYA simplified method of numerical analysis based on elasticity theory has been developed for the analysis of axially and laterally loaded piled raft foundations embedded in non-homogeneous soils and incorporated into a computer program ''PRAB''. In this method, a hybrid model is employed in which the flexible raft is modelled as thin plates and the piles as elastic beams and the soil is treated as springs. The interactions between structural members, pile-soil-pile, pile-soil-raft and raft-soil-raft interactions, are approximated based on Mindlin's solutions for both vertical and lateral forces with consideration of non-homogeneous soils. The validity of the proposed method is verified through comparisons with some published solutions for single piles, pile groups and capped pile groups in non-homogeneous soils. Thereafter, the solutions from this approach for the analysis of axially and laterally loaded 4-pile pile groups and 4-pile piled rafts embedded in finite homogeneous and non-homogeneous soil layers are compared with those from threedimensional finite element analysis. Good agreement between the present approach and the more rigorous finite element approach is demonstrated.

Vertical dynamic response of pile in a radially heterogeneous soil layer

“…Generally speaking, the soil is inhomogeneous not only in the vertical direction but also in the radial direction, especially for the soil region adjacent to the pile for the reason that the soil properties may be changed during pile construction when soil compaction or soil relaxation may occur. Some investigators [11,12] have dealt with the soil inhomogeneity by means of numerical finite element methods but rarely, if at all, by analytical methods. Guo and Randolph [13] addressed the response of axially loaded pile in a generic inhomogeneous soil where stiffness and strength vary monotonically with depth, but did not consider soil inhomogeneity in the radial direction.…”

Non-linear analysis of vertically loaded piled rafts

“…4 and described by Kitiyodom and Matsumoto [15]. The settlement of the piled raft and the percentage of total load (V = 900 kN) carried by the raft are reported in Fig.…”

“…Winkler approaches employ a ''plate on springs'' model in which the raft is represented by a plate and the piles as springs (e.g. [7,25,15,19,22,13]). Although such approaches are attractive in their flexibility (e.g.…”

Influence of reaction piles on the behaviour of a test pile in static load testing

“…The problem is dealt with using a simplified deformation analytical program PRAB that has been developed by Kitiyodom andMatsumoto (2002, 2003). This program is capable of estimating the deformation and load distribution of piled raft foundations subjected to vertical, lateral, and moment loads, using a hybrid model in which the flexible raft is modelled as thin plates and the piles as elastic beams and the soil is treated as springs (Figure 1).…”

“…In addition, an averaging technique suggested by Poulos (1979) is incorporated into the analysis to approximate the interaction between the structure members of a piled raft foundation embedded in non-homogeneous soils. The accuracy of this approximate technique had been examined in Kitiyodom and Matsumoto (2003) through comparisons with several published solutions and three-dimensional finite element analysis. Note that the solutions from the approximate technique are comparable with the closed form solutions of the interaction given by Mylonakis and Gazetas (1998).…”