Studies on the Performance of Under-reamed Piles in Sandy Soil through Model Tests

Abstract

Predicting pile behavior and estimating pile capacity in different soil conditions are critical in building industry. This paper describes an experimental study which is aimed to comprehend some factors affecting the under-reamed pile capacity in sand i.e. the bulb angle and bulb spacing. It also compares the variation of capacities of these piles in sand in both loose and dense state. A total of 9 model piles were tested, which included four single under-reamed piles, four double under-reamed piles and a normal pile. From the experimental studies, load–settlement curves are obtained and the pile capacities are determined using various criteria reported in the literatures. The capacity increased to at least twice the value when an under-ream bulb was introduced to a normal pile. The pile with bulb angle of 45⁰ and with bulb spacing of 1.25 times the bulb diameter showed maximum capacity for single under-reamed and double under-reamed piles, respectively. The pile capacity increased with increase in sand density. The test results are in agreement with the relevant Indian Standards.