Centrifuge Modeling of a Pile-Supported Granular Earth-Platform

Soil reinforcement by vertical rigid piles is a suitable technique to solve soft-soil foundation problems. This technique consists of transferring the load of a pile-supported structure to a resistant, less compressible soil layer. The loads are transferred on pile heads by arching mechanisms in an earth-platform located between piles and structure. The role of the earth-platform is to distribute the loads among the piles and to minimize the fraction of the load applied on the soft compressible soil. Centrifuge tests are performed at 12and20xg levels of acceleration with a specific apparatus containing 63 rigid piles. The behavior of a granular earth-platform with rigid pile reinforcement is studied. The granular earth-platform is simulated with Hostun sand. The physical model is widely instrumented to compare the load-transfer efficiency and the surface settlements for several geometrical configurations. The influence of the height of the earth-platform and the spacing between the piles on load-transfer mechanisms are discussed as well as the effect of a cyclic loading. In this study, the low-height earth-platform is investigated to simulate extreme geometrical conditions. These low-height earth-platforms are suitable for low compressible soils, and in some cases a concrete slab is used above this platform.