Search

The response of laterally loaded piles installed near the crest of clay slopes is analysed. Three-dimensional finite element analyses are presented for piles at various distances from a slope crest and for different pile shape. The results of these analyses are used to study the variation of the pile displacement, the bending moment of the pile and the soil resistance in relation to pile to slope distance and pile shape. The obtained results show that the proximity of slope significantly affects the lateral load capacity of the piles but not significantly when the piles are placed at 7D (where D is pile diameter) or greater from the slope crest. Furthermore, the lateral soil resistance on the ground surface for circular piles is larger than that for rectangular piles at the same lateral load in level ground. The decrease rate of lateral soil resistance on the ground surface for circular piles gets faster as the slope ratio and load level increase. [ABSTRACT FROM AUTHOR]

• This paper presents an analytical approach for predicting laterally loaded pile-soil interaction in saturated soils. • The soil deformation mechanism around the pile is determined using the constitutive model, MCC. • The p-y curve is derived by considering axisymmetric condition, equilibrium equation, and boundary conditions. This paper proposes an application of the cavity expansion theory to predict the load-displacement response of monotonically laterally loaded piles and the effective stress distribution of saturated modified Cam-clay (MCC) soil surrounding the pile. This approach incorporates geometric relationship, equilibrium equation, and boundary conditions to derive governing equations. These equations are subsequently solved to obtain monotonic p-y curves, which encompass the elastic, elastoplastic, and critical processes. To determine the load-displacement behavior and effective stress distribution of the soil, the proposed approach combines the deflection equilibrium differential equation with the finite-difference method. The accuracy and effectiveness of the approach are validated through a comparison with a Finite Element Method (FEM) simulation. Parametric studies are also presented to investigate the effects of overconsolidation ratio, in-situ coefficient, and mean effective stress. The validity and capacity of the proposed model are further demonstrated using model pile tests. The results affirm that this approach can well predict the monotonic load-displacement response of the pile and effectively captures important phenomena observed in pile tests. [ABSTRACT FROM AUTHOR]

Three-dimensional (3D) finite element analysis is used to investigate the vertical and horizontal bearing capacity of internal skirted foundations in normally consolidated uniform clay under undrained condition. The vertical and horizontal bearing capacity analysis has taken the effects of embedment ratio, foundation–soil interface roughness and soil strength heterogeneity into account. In this paper, new equations have been proposed for calculating vertical and horizontal bearing capacities based on the results of the finite element analyses. In the proposed equations, the vertical capacity consists of an end-bear resistance and a skin friction resistance, whereas the horizontal capacity consists of a normal resistance, a radial shear resistance and a base shear resistance. By comparing the numerical results, it shows that the proposed equations properly predicted the bearing capacities of the internal skirted foundations in uniform or non-uniform clay under undrained condition. [ABSTRACT FROM AUTHOR]

In this paper, a method is developed for nonlinear analysis of laterally loaded long-flexible pile near undrained clay slope. The ideal elastic-plastic p-y curve model is used as the basic calculation model to study the pile-soil interaction system. To consider the slope effect on the soil resistance along with pile length, related reduction function expressions of soil resistance are selected by assessing the existing methods. A finite difference iteration scheme is proposed to solve the pile’s deflection curve equations to obtain nonlinear response of pile. The developed method is validated by comparing its results with the existing method, which shows a good agreement. A number of parameters analyses are carried out, and effects of different influence factors on laterally loaded pile are further discussed. [ABSTRACT FROM AUTHOR]

A series of three-dimensional finite element analyses were performed to study the behavior of piles in sloping ground under undrained lateral loading conditions. The analyses have been conducted for slopes with different angles and two loading directions. The obtained results show that as the slope increases, it can cause greater lateral displacement and internal force of the pile. In addition, the increase of the slope ratio will cause the position of the maximum bending moment and soil resistance zero point of the pile to move downward, further increasing the pile deflection. Furthermore, when the pile distance from slope crest B < 7D, the displacement and internal force development of the pile under toward loading is more obvious. When the pile distance from the slope crest exceeds 7D, the effect of loading direction on the pile can be neglected. [ABSTRACT FROM AUTHOR]

This paper proposes an analytical method for laterally loaded piles in sand, in which the strain wedge model and failure wedge model are used together. To determine the process that develops from the strain wedge model to the failure wedge model, a 3D finite element analysis is carried out. Considering the continuity of the soil resistance, the relationship between the strain wedge model and failure wedge model is established. Two failure patterns in which the soil develops from the strain wedge model to the failure wedge model are discussed. The lateral response of the pile and soil is obtained by an iterative calculation. Two centrifuge tests are used to evaluate the accuracy of the new method, showing remarkable agreement. [ABSTRACT FROM AUTHOR]

This paper proposes a method for nonlinear analysis of a rigid pile under lateral load at the crest of clay slope. It is assumed that the ultimate soil resistance in front of the pile and behind the pile vary nonlinearly with depth. The modulus of horizontal subgrade reaction in front of the pile and behind the pile vary nonlinearly with the pile displacement at ground surface. The horizontal shear resistance at the pile base is considered and a bilinear relationship between the shear resistance and the displacement is used. Three distribution patterns of the soil resistance along a pile are also considered. Based on the force and moment equilibrium, the system equations are derived for a laterally loaded rigid pile in sloping ground with different soil resistance distribution patterns. The proposed method is validated by comparing its results with those from field tests, finite element analyses and a theoretical method. Finally, the method is used to analyze the effect of slope angle, pile-soil adhesion factor, height above ground surface of point of load application, pile diameter and embedded length on the lateral response of rigid piles. [ABSTRACT FROM AUTHOR]

This paper investigates the roof collapse of deep circular cavities in jointed rock masses using adaptive finite element limit analysis. The rock mass strength is described by the generalized Hoek-Brown failure criterion. The calculated results of the stability number N s are presented in the form of dimensionless stability charts and are compared to the transformational results of an analytical upper bound solution by former investigators. The transformations are conducted using an algorithm proposed in the appendix of this paper. Parametric studies are performed to investigate the impacts of the Hoek-Brown parameters on the stability number and failure mechanism of underground cavities. In particular, different levels of rock mass disturbance are considered by adopting various rock mass disturbance factors D in the analyses. [ABSTRACT FROM AUTHOR]

Seven soil-pile interactions and four change processes of soil-pile interaction are proposed to predict the deflection of large-diameter monopile near undrained clay slope under a lateral load in this paper. The equations of force and moment are established in each soil-pile interaction, and the predictive load-deflection curves are obtained by solving those equations. The effect of slope and near-slope distance on the p – y curves is considered. The relationship between ultimate soil resistance and depth is divided into two forms according to the near-slope distance, and the ultimate soil resistance varies nonlinearly with the depth. The modulus of horizontal subgrade reaction in front of pile and behind the pile vary bi-linear and constant with the depth, respectively. To evaluate the accuracy of the new method, it is compared with the results of field tests and the finite element analysis. Finally, the method is used to analyze the effect of slope angle, near-slope distance, pile-soil adhesion and base resistance on lateral deflection. [ABSTRACT FROM AUTHOR]