Interaction of concrete and soil structures

Structure/soil interaction is partly a neglected problem, probably because in the engineering curriculum it overlaps different departments and partly because it is a rather complex problem.
In recent years a number of cases have been reported, where concrete walls have been damaged due to a faulty evaluation of the structure/soil interaction. The most difficult problems arise, when the structure is rather brittle, for instance an unreinforced concrete structure.
In the first phase of the project it is attempted to get a better understanding of the constitutive properties of soil. This is done by developing a so-called toy model. A toy model is a model, which can be used for illustrating a phenomenon, but it cannot normally be used for accurate quantitative calculations. The toy model consist of cylinders with friction (Danish: pinde model).
Different packing arrangements are assumed with the purpose to study standard failure tests like the shear box test and the triaxial test. Other packings are used to illustrate the constitutive equations up to failure. Finally, the model is used to evaluate the effect of elastic deformations in the contact zones relative to deformations due to sliding.
In the next phase a new earth pressure theory is developed. It is based on strict equilibrium stress fields contrary to the mixture of upper- and lower bound solutions. normally used.
Further a new optimization technique is developed which is able to deal with problems of a size encountered in practise. The optimization procedures, as for example linear programming routines, are only able to solve problems of academic interest. The new method will be based on a combination of a series of linear elastic solutions with modified stiffness matrices depending on the yield condition for the material. It is hoped that this methoc can also be used to treat brittle structure/soil interaction.