Soft Ground Improvement by Vertical Rigid Piles Two-Dimensional Physical Modelling and Comparison with Current Design Methods

Abstract

ABSTRACT Soft soil improvement by vertical rigid piles permits reduction and homogenization of settlements under structures. This process provides an economic and effective solution, especially when rapid construction is required. The field applications are mainly roadways, railways and industrial building foundations. Piles are installed into the soft soil and rest on a substratum, which is a more rigid layer. Loads applied on surface are transferred to the pile caps, thanks to a granular mat, added on the soft layer, in which arching occurs. This paper describes the main features of the improvement and summarizes several calculation rules for the design. Some physical models of piled earth platform from the literature are presented. A two-dimensional small scale model was developed and some experimental results are presented. The granular soil mat is modelled by the two-dimensional Taylor-Schneebeli analogical material, the soft soil is modelled by foam and the piles are modelled by metallic elements. The instrumentation permits the analysis of the load transfer on piles and an image correlation method permits the analysis of the displacement fields in the model. The experimental results are compared to several current calculation methods.