Numerical Analysis and Design of Bored Concrete Pile Foundations

Abstract

Bored concrete piles are mostly used in Sudan Khartoum area for tall building, bridges and other heavily structures where the soil under which is very weak. The purpose of this study is to analyze and design bored piles under general conditions of load in Khartoum area, particularly at Soba bridge site, to study how pile transform these loads to the ground. how these loads are distributed in each pile within the group piles and design it. Using manual empirical formulas and computer software Allpile 6.5 to analyze different pile diameters (1.2,1.4,1.6and 1.8m), different pile lengths (25.9,32.9, and 35.9) and different numbers of pile groups (1x4,2x4 and3x4) subjected to vary load combinations to study the effect of change in diameter, length and number of piles in groups on pile behavior. The results of settlement, deflection, axial, lateral load and moment on each pile in group were obtained to compare the results from manual empirical formulas with numerical software Allpile 6.5 and with the actual results which the bridge was designed. The study has shown that the results of numerical software Allpile 6.5 analysis, manual empirical formulas calculations analysis and actual results are almost the same for the vertical load results. However, about the results of moment and lateral load the actual results which show large different compared to the software Allpile 6.5 and manual empirical formulas calculations results which they are often close. The results indicate that the decrease in length effects on increase the settlement about 14.14% and the increase of diameter effect on the decrease the settlement by 22.59%. but the change in length does not influences on deflection. Also Increase the number of piles in the group decrease the loads applied on each pile. finally, the pile has been designed calculating the reinforcement for safety and durability. Comparison of this with the actual design shows that more pile length is required because the actual length is 25.9m for 1X4 group, the satisfied length for the design requirement in this research is 35.9m for 1X4 group.