Effect of central pile in increasing the bearing capacity of bored pile groups

Abstract

The base resistance of smooth model pile groups in sand under static loading is investigated experimentally in a pile soil test apparatus. The study investigated the design of the pile foundation to support heavy structures -especially bridges for highways and railways - in the Sahara, which contains many dunes of loose to medium sand in different levels, where the foundation is supposed to be piles. In this case, cased (cast in-situ) bored piles are more economical than uncased piles. Improvement was made to the sand around the piles in order to increase the shaft resistance of the piles in the groups, and also base resistance especially for the central pile in pile groups. The study shows the effectiveness of improving the sand around the piles in increasing the bearing capacity of the pile group and increasing the bearing capacity with increasing embedment length of piles in the group. The study outlines the behaviour of 9-pile groups arranged in a doubly symmetric [square] layout with different embedment lengths and pile spacing in medium dense dry sand [normal] and dense dry sand [compacted] around the piles.