Assessing Shallow Foundation Responses to Adjacent Excavation in Clay

Abstract

In developing countries like Pakistan, the high population growth rate has caused an increase in urbanization.
To accommodate the growing population, there is a dire need for high-rise buildings, especially in the most densely
populated cities. Consequently, traffic and parking issues have also increased. To cope with these issues, deep
excavations for underground facilities and high-rise buildings in urban areas are often carried out adjacent to existing
historic or old buildings founded on shallow foundations. Excavations may cause unfavorable ground deformations that
affect neighboring structures, presenting a significant challenge for civil engineers to protect integrity of these historical
structures. This research presents 3D coupled consolidation analyses using a clay hypoplastic constitutive model, which
accounts for small-strain stiffness, to investigate responses of a shallow foundation to neighboring excavation at
different depths and clear distances between footing and diaphragm wall in soft clay. It was revealed that the excavation
depth and clear distance between the footing and the diaphragm wall significantly affect induced settlement and lateral
movement due to excavation. Moreover, the apparent losses in bearing capacity due to induced settlement of the footings
located at 1.0, 1.5, 2.0, 4.0, 6.0, and 8.0 meters from the diaphragm wall are 1.65, 1.73, 1.81, 1.70, 1.53, and 1.30 times
the ultimate capacity, respectively.