THE BEHAVIOUR OF GEOTEXTILE REINFORCED EMBANKMENTS

The effect of geotextile reinforcement on the stability of granular embankments constructed on deposits of fibrous peat and/or soft clay is investigated using the finite element method. The method of analysis is shown to provide good agreement between calculated and observed performance of two published case studies of reinforced embankments. Analyses are performed for a number of hypothetical embankments and the results are used to develop simple design methods for geotextile-reinforced embankments constructed on fibrous peat and/or soft clay. The implications of the finite element results with regard to modified limit equilibrium analysis of reinforced embankments on soft clays are discussed.;The analyses of embankments constructed on fibrous peat indicate geotextile reinforcement can significantly increase stability and reduce lateral spreading of embankments but has little effect on consolidation settlements.;For embankments constructed rapidly on soft clays, it is shown that the effect of geotextile reinforcement on embankment stability can be quite substantial. The effect is particularly significant for embankments constructed on soft clays whose strength increases with depth, where increases in failure heights of up to 100% were predicted.;For every case considered, the effect of geotextile reinforcement on embankment performance is found to be greatest for high modulus geotextiles and shallow deposits.;The success of limit equilibrium calculations in predicting the stability of embankments on soft clay depends on the ability to accurately predict the force mobilized in the geotextile at embankment failure. To this end, a limit equilibrium method is proposed for estimating stability of reinforced embankments on soft clays whose strength is constant with depth. The method uses a rational approach for estimating geotextile strains mobilized at embankment failure, based on finite element results.;Finally, the proposed simple design methods are evaluated by comparing predicted embankment performance with observed performance for a number of published case histories. The proposed methods are shown to provide "design recommendations" consistent with observed embankment performance for the cases examined.