A simplified approach for nonlinear analysis of the load-displacement response of a Single pile and a pile group is presented using the load-transfer approach. A hyperbolic model is used to capture the relationship between unit skin friction and pile-soil relative displacement developed at the pile-soil interface and the load-displacement relationship developed at the pile end. As to the nonlinear analysis of the Single pile response, a highly effective iterative computer program is developed using the proposed hyperbolic model. Furthermore, determinations of the parameters related to the hyperbolic model of an individual pile in a pile group are obtained considering interactions between piles. Based on the determinations of the parameters presented in the hyperbolic model of an individual pile in a pile group and the proposed iterative computer program developed for the analysis of the Single pile response, the conventional load-transfer approach can then be extended to the analysis of the load-settlement response of an arbitrary pile in a pile group. Comparisons of the load-settlement response demonstrate that the proposed method is generally in good agreement with the field-observed behavior and the calculated results derived from other approaches.

pile groups mostly are used for translating the load of structures to soil and a pile cap is used on the top of the group. Lateral loading in designing pile group is important. In pile group under lateral loading, each pile is influenced by neighboring piles. The spacing between piles has an important effect on lateral bearing capacity.

Previous case histories have shown that soil liquefaction severely damaged many structures supported on pile foundations during earthquakes. As a result, evaluating the potential for instability is an important consideration for the safe and resistant design of deep foundation against earthquakes. In this study, the liquefaction susceptibility of saturated sand interacting by Single concrete pile was simulated by means of finite difference method. A nonlinear effective stress analysis was used to evaluate soil liquefaction, and the soil-pile interaction was considered using interface elements. The parameter Ru was defined as the pore water pressure ratio to investigate liquefaction in the soil mass during time. A set of numerical models were carried out by three types of soil mass with various condensation (loose, semi-dense and dense) under three ground motion with different predominant frequencies and peak accelerations. The effect of these parameters was studied using excess pore pressure, lateral movement and settlement time histories. It was found that the pile can affect the liquefaction susceptibility of soil by comparing the near pile and free field responses. However, for various soil and earthquake characteristics, it was found that the depth of soil liquefaction and triggering, varies.

The subject of pile foundation subjected to lateral cyclic load is an age-old problem confronted by Geotechnical Engineers. The environment prevalent in ocean necessitates the piles supporting offshore and onshore structures to be designed against lateral cyclic loading resulting from the effects of sea waves. Such loading induces remarkable deterioration in the interactive performance of the soil-pile system. This can be manifested as significant loss in pile capacity associated with increased pile head deflection. The work reported herein is aimed towards conducting extensive experimental investigation on model pipe pile in marine clay under lateral cyclic loading, subsequently followed by theoretical analysis using finite difference technique. The experimental results are compared with the theoretical results and reasonably good agreement is noted. This paper presents brief description of the experimentation and theoretical analysis carried out with some typical results and the relevant conclusions drawn therefrom.