بهمن نیرومند

This paper deals with the effect of closed-end and cone-shaped of mandrel (shuttle) on its penetration rate into a loose soil bed under a high frequency cyclic load in order to implementation of Gravel Impact Compaction Piers (GICP). The gravel impact compaction piers are one of the methods for improvement of loose sandy soils, which, in addition to creation of radial compaction of peripheral soil around the piers, retrofit loose soil bed against liquefaction and results in increased bearing capacity and subgrade modulus reaction and decrease bed settlement. The method of doing research has been as laboratory and small scale. To doing this research, special equipment has been used that has been designed and constructed merely for purpose of this research. The results of performing small scale experiments in the sandy soil of Alishahr new town of Bushehr port indicate that with decreasing of the angle of the end cone, less energy is used for hammering the shuttle, and from 6 different cones, cone with a 67degree angle selected as optimal practical angle.