Deep excavations in soft soil - Finite element analysis and in-situ measurements

Numerical methods are increasingly employed for analyses of deep excavations because of their considerable advantages over classical methods with respect to predicting deformations, especially surface settlements. However, it is not always easy to include the complete excavation sequence as it is performed on site in the computational model. Field measurements to check the results of the numerical analyses are only occasionally available to that scale which would be appropriate. In this paper results from a two dimensional finite element analysis of a diaphragm wall are compared to in-situ measurements. The effect of lowering the water table is taken into account in a very simple way which seems to be sufficiently accurate for practical purposes under the given conditions. A time consuming and expensive analysis based on consolidation theory could be avoided and with some engineering judgement the results could be interpreted to explain the phenomena observed in the field.