The efficiency coefficient of 3×3 piles group in cohesion soil using small scaled pile group model

Abstract

This paper deals with the investigation of a model experimental study of group piles of different length to diameter ratio (L/D) as well as different spacing (S) between the piles in the group. The piles were installed in clayey soil and sand-clay alternative layering soil and sujected to axial loading condition. Group efficiencies of small scaled piles groups were determined at length to diameter ratio varying from 20 to 30 and at 3D and 6D spacing between the piles. The behavior of pile on the experimental model was then simulated by using Plaxis 3D Foundation software. Ratio of length to diameter has been found to be a major factor that influences ultimate axial resistance of the group and the group efficiency (η). The group efficiency (η) in these types of soils is less than 1. The results show that when increasing the pile length, η increases significantly. When the ratio of pile spacing to diameter (S/D) increases, η increases. The results also show that reducing the thickness of clayey soil and increasing the thickness of strong soil under the pile will strengthen the soil and increase the bearing capacity of pile group.

Keywords:Efficiency coefficient;group efficiency; pile group; distance of piles