A Semianalytical Solution for Passively Loaded Piles Adjacent to Surcharge Load

Piles adjacent to a surcharge load commonly support not only active loads from superstructures but also the passive loads caused by soil lateral movement. To investigate the influence of passive load and the response along pile shafts of existing actively loaded piles, a load transfer model for analyzing the soil-pile interaction was developed based on plastic deformation theory and the triparameter soil model. An analytical solution for the deformation and internal force of such piles was proposed using the transfer matrix method, in which the transfer matrix coefficients for piles in free, plastic, and elastic zones were analytically obtained by considering the second-order axial force effect caused by lateral loading and soil yielding based on the triparameter soil model. The proposed methodology was validated by comparing its predictions with field measurements and previously published results. A good match between model predictions, field measurements, and previously published results implies that the proposed method can be used to evaluate the response of passive piles adjacent to a surcharge load. Parametric studies were also carried out to investigate the influence of surcharge pressure, soil resistance, and boundary conditions on the behavior of passively loaded piles adjacent to a surcharge load.

Nonlinear response of laterally loaded rigid piles in sliding soil

This paper proposes a new, integrated two-layer model to capture nonlinear response of rotationally restrained laterally loaded rigid piles subjected to soil movement (sliding soil, or lateral spreading). First, typical pile response from model tests (using an inverse triangular loading profile) is presented, which includes profiles of ultimate on-pile force per unit length at typical sliding depths, and the evolution of pile deflection, rotation, and bending moment with soil movement. Second, a new model and closed-form expressions are developed for rotationally restrained passive piles in two-layer soil, subjected to various movement profiles. Third, the solutions are used to examine the impact of the rotational restraint on nonlinear response of bending moment, shear force, on-pile force per unit length, and pile deflection. Finally, they are compared with measured response of model piles in sliding soil, or subjected to lateral spreading, and that of an in situ test pile in moving soil. The study indicates the following: (i) nonlinear response of rigid passive piles is owing to elastic pile–soil interaction with a progressive increase in sliding depth, whether in sliding soil or subjected to lateral spreading; (ii) theoretical solutions for a uniform movement can be used to model other soil movement profiles upon using a modification factor in the movement and its depth; and (iii) a triangular and a uniform pressure profile on piles are theoretically deduced along lightly head-restrained, floating-base piles, and restrained-base piles, respectively, once subjected to lateral spreading. Nonlinear response of an in situ test pile in sliding soil and a model pile subjected to lateral spreading is elaborated to highlight the use and the advantages of the proposed solutions, along with the ranges of four design parameters deduced from 10 test piles.