Study on Uplift Behavior of Single Belled Anchor Piles in Sand Bed and Multiple Regression Analyses

Abstract

This study analyzed series of experimental study performed to evaluate the contribution of belled anchor piles at embedment ratio of 3, 4 and 5, diameter ratio of 0.28, 0.33, 0.38 and 0.46, and bell angle of 45, 54, 63 and 72°. In total 96 tests are carried out on uplift capacity vs. anchor displacement behavior of belled anchors in two different types of sand deposit possessing density of 15.60 and 16.90 kN/m3 and internal angle of friction of 33 and 39.5° respectively. The influences of above mentioned parameters on net ultimate uplift capacity are explored on the basis of experimental data. The comparison of predicted values of breakout factor on lesser dense sand based on predictive models of previous researchers, shows wide variation with present data. The comparison of predicted values on higher dense sand based on few predictive models of earlier researchers, shows good correlation with present data. But the variations on predicted values accounted from earlier models represent wide conflict amongst. Moreover the earlier predictive models are developed for dense sand only. Hence, an attempt has been made to establish total six numbers of multiple regression equations with the help of experimental breakout factor values to predict the breakout factors. These multiple regression equations have been verified with few present data which are not used to develop the equations and also with experimental data of previous study. Based on six numbers of multiple regression equations, errors are within 0 to 10%, 10 to 15%, and 15 to 20% in case of almost 66%, 22% and 9% of predicted values respectively, verified with the observed data of earlier studies as well as present data.