Date of Award


Degree Type


Degree Name

Doctor of Philosophy


The behaviour of both geosynthetic and steel strip reinforced embankments constructed on soft foundations is investigated using the finite element method.;The results of finite element analysis are shown to be in good agreement with the observed performance of a full-scale geogrid reinforced embankment constructed on a very soft deposit of peat and organic silt. Stage I construction was back-analyzed using information obtained from the program of field monitoring together with engineering properties of the soils obtained from laboratory tests.;Finite element analyses are used to study the effects of reinforcement such as high modulus geosynthetics and steel strips, on the undrained behaviour of embankments constructed on soft clayey foundations where the undrained shear strength and modulus increase with depth. It is shown how the response of the foundation soil in terms of shear strain is influenced by such factors as; (1) load level, (2) reinforcement modulus, (3) foundation soil modulus and (4) the presence of a higher strength surface crust in the foundation. The use of a suitable reinforcement may substantially reduce the magnitude of the foundation shear strains beneath the embankment. This is of practical significance where the foundation soil may be susceptible to strain softening and the selection of a suitable reinforcement may help to reduce the magnitude of shear strains under working conditions and hence improve stability. The implications of these results with regard to the selection of a limiting geosynthetic strain for use in conventional analysis methods are also discussed.;A nodal compatibility interface joint element which models the pullout behaviour of strip reinforcement is introduced. This interface joint element is incorporated in a finite element study of the behaviour of steel reinforced embankments constructed on soft clay foundations. It is shown that the amount of steel strip reinforcement provided significantly influences the behaviour of these embankments.;Finally, a closed form limit equilibrium method of analysis is proposed and based on comparison with rigorous finite element analyses, appears to provide a simple but reasonable estimate of the undrained stability of reinforced embankments on soft cohesive deposits.



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