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Aktaş Ş., Aracı F., Yıldız C., Berilgen M. M. , Özaydin I. K.

7th Geotechnical Symposium with International Participation, İstanbul, Turkey, 22 - 24 November 2017, pp.591-598

  • Publication Type: Conference Paper / Full Text
  • City: İstanbul
  • Country: Turkey
  • Page Numbers: pp.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.