Practical Models and Parameters for Settlement Calculation of Deep Foundation of Super High-Rise Buildings on Soft Subgrade

In 1867, Winkler put forward the most simple linear-elastic ideal model, which assumed that pressure of each point on the medium surface of subgrade is in direct ratio with the vertical displacement of this point, and is completely irrelevant with pressure of other points on the interface between subgrade and foundation. Although this assumption has some disadvantages, it is still applied now. Another ideal model describes subgrade medium by elastic half-space continuum, i.e. the elastic half-space foundation model, which takes into account the continuity feature of subgrade, and integral equation calculation is needed accordingly for the analyzing process of the interaction between subgrade and foundation. So this model has more complex calculation process, and the result of internal force of foundation is larger than real. Afterwards, Filonelko-Borodich (1940), Hetenyi (1946), etc, put forward a kind of intermediate double-parameter subsoil models, which was a intervenient one between Winkler foundation model and elastic half-space foundation model. One of such models introduces the mutual mechanics action between springs to make the result more sensible by breaking the limit that the displacement of subgrade medium surface is within the area of load, based on Winkler subsoil model. Cross isotropic model is a linear-elastic model, which considers the stratum feature of subgrade medium. Recently, application of the layered model is more popular in the field of subgrade-structure interaction analysis, the result is between Winkler subsoil model and elastic half-space subsoil model, and is more reasonable. For the complexity of properties of soft subgrade, new models are still to be researched to consider the factors of non-linear feature, elastoplastic feature, and time-dependent feature of subgrade.