Analysis of reinforced embankments and foundations overlying soft soils

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Virginia Polytechnic Institute and State University

The use of tensile reinforcement to increase the tensile strength and shear strength of soils has lead to many new applications of reinforced soil. The use of such reinforcing in embankments and foundations over weak soils is one of the most recent applications of this technology. The studies conducted were concerned with the development of and application of analytical techniques to reinforced soil foundations and embankments over weak soils.

A finite element computer program was modified for application to reinforced soil structures, including consolidation behavior of the foundation soil. Plane strain and axisymmetric versions of the program were developed and a membrane element developed which has radial stiffness but no flexural stiffness. The applicability of the program was verified by comparing analytical results to case histories of reinforced embankments and to model studies of reinforced foundations.

A simplified procedure for computing the bearing capacity of reinforced sand over weak clay was developed which is more general than those previously available. Good agreement with available experimental results was obtained, providing preliminary verification of the procedure.

Extensive analyses were made of a reinforced embankment successfully constructed with no sign of distress, and of two reinforced embankments constructed to failure. These analyses showed that good agreement can be obtained between measured and calculated reinforcement forces, settlements, and pore pressures for both working and failure conditions. The analyses further show that the use of the finite element method and limit equilibrium analyses provide an effective approach for the design of reinforced embankments on weak foundations.