Ultimate Capacity Analysis and Determination of the Position of Failure Surface for Uplift Piles

Qian Su,Xiaoxi Zhang,Pingbao Yin,Wenhui Zhao

doi:10.1155/2014/540143

Abstract

Ultimate capacity and failure surface position of uplift piles are dependent on soil parameters. In this paper, the horizontal slice method is used to discuss the relation among the ultimate uplift capacity, the failure surface position, and soil parameters with Mohr-Coulomb failure criterion. According to the limit equilibrium analysis, the ultimate uplift capacity is calculated by dividing soil around the pile into slices with considering the potential failure surface as a group of several sectional planes. Then the multivariate function used to calculate ultimate capacity is established and optimized by the sequential quadratic programming. Through the numerical calculation and comparison with the previous research, the results show that the method is reasonable and effective and can be used to determine the failure surface and the magnitude of the ultimate capacity of uplift piles.

Highlights

Uplift piles are commonly used as foundation systems for structures requiring uplift resistance such as high-rise structures and transmission lines
Shin et al [8] presented laboratory model test results for estimation of the ultimate uplift capacity of rigid metal piles embedded in a compacted near-saturated clayey soil
The failure surface moves to the pile gradually with decreasing cohesion and internal friction angle

Summary

Introduction

Uplift piles are commonly used as foundation systems for structures requiring uplift resistance such as high-rise structures and transmission lines. The pile-soil interaction mechanism is not well understood, and very few papers are available to analyse the ultimate uplift capacity and failure mechanism. Deshmukh et al [1] estimated the uplift capacity of pile anchors in cohesionless soil using Kotter’s equation and assuming the cone frustum failure surface. Shanker et al [4] presented a simple semiempirical model for predicting the uplift capacity of piles embedded in sand. They are only applicable for sand and cohesionless soil. Shin et al [8] presented laboratory model test results for estimation of the ultimate uplift capacity of rigid metal piles embedded in a compacted near-saturated clayey soil. We report net uplift capacity of the pile compared with previous researches

Load Transfer Mechanism of Uplift Pile

Theoretical Model

Verification and Numerical Result

Method

Findings

Summary and Conclusions