ABSTRACT

It is well recognised that superstructure load i s transferred to surrounding soil through pi led foundation. Consequently, the high stress regime (stress bulb) is generated surrounding of the pile. On the other hand, the excavation in the ground inevitably results in the ground movement due to induced-stress release. To cope with transportation problems in congested cities in the world like Hong Kong, Shanghai, London etc, underground transportation systems (involving tunnels for metros, excavations of metro stations and basement to facilitate inhabitants in the buildings for parking) have been developed. These excavations are sometimes inevitable to be constructed adjacent to existing piled foundations. This condition leads to a big challenge for civil engineers to assess and protect the integrity of piled foundation. This research presents three-dimensional coupled consolidation analyses (using clay hypoplastic constitutive model which takes account of small-strain stiffness) to investigate the responses of a friction and an end-bearing pile due to adjacent excavation at different depths in soft clay. It was revealed that the maximum induced bending moment in both types of piles after completion of excavation in all the cases is much less than the pile bending moment capacity (i.e. 800 kNm). Moreover the end-bearing piles were subjected to significant dragload due to negative skin friction. In contrast no significant changes in load distribution along friction piles were computed.