Akademik Veri Yönetim Sistemi
7th Geotechnical Symposium with International Participation, İstanbul, Türkiye, 22 - 24 Kasım 2017, ss.591-598
Deep excavations are used for foundation of multi-basement structures, subway stations and
other underground structures. Deep excavations must be supported by geotechnical structures
to avoid any damage to infrastructure and neighbouring buildings. These supporting systems
may comprise different and complicated horizontal, vertical or diagonal structural elements.
Other possible complications in the design of support structures may arise from presence of
laminated, non-linear soil behaviour, existence of surrounding structures and uncertainties in
groundwater level. In these situations, forces acting on the retaining elements may differ
during excavation from considered design forces; besides, strength and stiffness of the soil
can be lower than expected. Use of instrumental observation during the excavation, may
prevent adverse effects of unexpected situations both in soil behaviour and the acting forces,
also observations gives time for precautions for a possible mishap. In this paper it is aimed to
emphasize the importance of instrumental observations. A case history about the observed
behaviour of a bracing system for an excavation of a 6200m2
area, nearly 550m circumference
and 27m depth is presented. Instrumental observation in the field during excavation indicated
that more than expected horizontal displacements have occurred in a 70m long section of the
excavation boundary. Considering these unexpected displacements, design of bracing system
is revised and the excavation is safely completed.