Peculiarities of designing piled-raft foundations for multi-storey and high-rise buildings

Abstract

Сurrently in Multi-Storey and High-rise building to avoid intolerable relative settlement of separate constructions raft foundations are used. In connection with excessive loads base settlement often exceeds assumed value. In that case pile foundations are used. Often pile foundations are applied in comparative favorable ground conditions at the surface of the base. In such cases increase the bearing capacity of foundations and reduce construction cost are questions of first-rate importance for designers. One of the ways to increase the bearing capacity of a piled foundation is taking into account soil resistance in the base of the raft. Raft is similar to shallow foundation and can transfer significant part of the load into the base. It allows reducing number of pile in the foundation or shortening their length. As a result building terms and foundation costs reduce considerably. However, nowadays in Belarus there is no reliable and suitable in design practice methods of calculation of piled-raft foundations. In order to devise such methods we have analyzed the results of piled foundation tests fulfilled by various authors up to date and have carried out series of field and laboratory investigations in Minsk. The most important results of the investigations are provided in the article.