Publication Abstract

Proceedings - Fifth International Conference & Exhibition on Piling and Deep Foundations, 1994, Bruges, Belgium, (DFI)

Foundation with piled rafts in slide sensitive area
C. Alen

In designing piled foundations, the bearing capacity is often treated as the governing factor. Often, however, the bearing capacity of the soil can be proved to be sufficient, in spite of the fact that experience shows that unpiled foundations will not work. The piles are then actually used to reduce settlements. In this paper there is a case presented, where piled rafts were used in a very slide sensitive area. The foundation concerned was for an office building in a town centre. The subsoil consisted of very soft clay sloping down to a little river. The condition for the construction was that the load for the building must be fully compensated, not to jeopardize the stability of the neighborhood. Together with an optimized light superstructure, sparsely piled rafts were chosen for the foundation. The purpose of the piles was mainly to neutralize differential settlements. A minimal number of piles were chosen, approximately compared to traditional piling. Otherwise, there was a risk that a landslide could be released by high pore pressure during the pile driving. The settlements were predicted by a numerical FEM-programme. The model, which was three-dimensional, included the soil, the piles as well as the superstructure. Follow-up measurements of the settlements during the period 1987-1994, prove that the foundation functions satisfactorily. The described project is a good example that shows that a carefully done design, can make solutions possible, which with a traditional approach would be rejected.

 article #836; publication #36 (IC-1994)