The objective of the present paper is to analyse by means of combined experimental investigations and numerical simulations the load settlement response of axially loaded jet grouting columns with the aim of defining a theoretical methodology for the design of jet grouting reinforced foundations. The results of a well documented experimental campaign including full scale axial loading and pull-out tests on different jet grouting columns are first presented together with preliminary investigations. Interpretation of the load settlement response is then performed by a back analysis with a finite element code. The adopted model allows interpretation of the interaction between columns and surrounding soil and a back analysis of the load transfer mechanisms taking place along the shaft and the base of columns. This analysis has been conducted by focusing on the role of the characteristics of jet grouting columns.