An analytical model for arching in piled embankments

Most analytical models for the design of piled embankments or load transfer platforms with geosynthetic reinforcement (GR) include two calculation steps. Step 1 calculates the arching behaviour in the fill and step 2 the load-deflection behaviour of the GR. A calculation method for step 2 based on the results of model tests has been published by Van Eekelen et al., 2012a, Van Eekelen et al., 2012b. The present paper analyses and presents a new model for step 1, which is the arching step. Additional tests, which are also presented in this paper, were conducted for this purpose. The new model is a limit-state equilibrium model with concentric arches. It is an extension of the models of Hewlett and Randolph (1988) and Zaeske (2001). The new model results in a better representation of the arching measured in the experiments than the other models mentioned, especially for relatively thin fills. Introducing GR in a piled embankment results in a more efficient transfer of load to the piles in the form of an arching mechanism. The load is then exerted mainly on the piles and the GR strips between the piles, on which the load is approximately distributed as an inverse triangle. The new model presented in this paper describes this behaviour and is therefore meant to describe the situation with GR. The new model provides a physical explanation for observations of the arching mechanism, especially the load distribution on the GR. Other observations with which this model concurs are the dependency on fill height and friction angle. The amount of arching increases with increasing subsoil consolidation and GR deflection. The paper describes how the new model relates to the development of arching as a result of subsoil consolidation.