Analytical Model for the End-Bearing Capacity of Tapered Piles Using Cavity Expansion Theory

Suman Manandhar,Noriyuki Yasufuku

doi:10.1155/2012/749540

Abstract

On the basis of evidence from model tests on increasing the end-bearing behavior of tapered piles at the load-settlement curve, this paper proposes an analytical spherical cavity expansion theory to evaluate the end-bearing capacity. The angle of tapering is inserted in the proposed model to evaluate the end-bearing capacity. The test results of the proposed model in different types of sands and different relative densities show good effects compared to conventional straight piles. The end-bearing capacity increases with increases in the tapering angle. The paper then propounds a model for prototypes and real-type pile tests which predicts and validates to evaluate the end-bearing capacity.

Highlights

The pile end-bearing capacity in sands is affected by the compressibility of soil, shear stiffness, and strength, and by the angle of tapering of the pile
The tapering effects must be taken into consideration when evaluating the end-bearing capacity of tapered piles [2, 3]
This research asserts the use of the spherical cavity expansion theory as a way of evaluating the endbearing capacity of tapered piles based on axial cylindrical model tests

Summary

Introduction

The pile end-bearing capacity in sands is affected by the compressibility of soil, shear stiffness, and strength, and by the angle of tapering of the pile. There are two main methods to evaluate the end-bearing capacity: a semiempirical method using SPT-N values and a theoretical approach based on geomechanical considerations. Yasufuku et al derived successfully an evaluation technique for the end-bearing capacity in nondisplacement straight cylindrical piles using a spherical cavity expansion theory for closed solutions [7, 8]. This research asserts the use of the spherical cavity expansion theory as a way of evaluating the endbearing capacity of tapered piles based on axial cylindrical model tests. The tapering angle is inserted in the analytical model to evaluate the ultimate end-bearing capacity of the spherical cavity expansion theory previously postulated by Yasufuku et al [7, 8]. The proposed model referred to predict and validate other prototypes and real-type pile reference data to estimate the end-bearing capacity

Methodology and Evidence from Test Results

Analytical Model to Evaluate End-Bearing Capacity

C Plastic Elastic

Validity of the Model

TO sand