PREDICTION OF SETTLEMENT OF STRIP FOUNDATIONS ON LAYERED SOILS

The prediction of the settlement of strip foundations on two-layer soil systems of finite thickness is described. The soil strata consist of a lower finite layer of isotropic homogeneous clay which is treated as a linear elastic material, and an upper layer of either vertically jointed rock or sand which cannot be modelled realistically in terms of classical elastic theories. Accordingly, the vertically jointed rock is treated as a shear beam with a constant shear modulus, whereas the sand is treated as a shear beam having a shear modulus which is assumed to be a function of strain level and confining stress.; The formulation and solution for the prediction of the surface settlement of a strip foundation on vertically jointed rock overlying clay are presented for the cases of uniform and non-uniform clay thickness. The application of the theoretical results is illustrated with a practical example wherein the influence of the stiffness of a frame structure, which is supported on a number of parallel strip footings is shown.; The results of the theoretical study for the two-layer system consisting of sand overlying a uniform clay layer are presented in the form of design charts. These charts may be used for the prediction of the consolidation settlement of isolated strip footings. It is shown that the charts are only applicable up to the point when passive failure occurs in the sand layer adjacent to the footing. The predicted mode of the passive failure is in agreement with experimental observations.