Location

Chicago, Illinois

Session Start Date

4-29-2013

Session End Date

5-4-2013

Abstract

TOOBA deep excavation project was conducted in a densely developed area in the North West of Tehran, capital of Iran, to provide space for 4 basement levels for multiple buildings around the already functional TOOBA tower. Besides excavating on 3 sides of TOOBA tower, this project involved excavation to the depths varying from 9 to 28 meters depending on the sloping ground condition. A 5 story school building and a 2 story residential building abut the excavation boundary. Previous experience of constructed soil nail walls in cemented soils of Tehran indicated relatively small wall deformations. Therefore, except for the retaining system of the TOOBA tower, a soil nail wall system was seen appropriate for supporting excavation faces. Wall and ground deformations were monitored during and after construction and the ground around the site was regularly checked for tension cracks. Geotechnical explorations indicated the presence of a disturbed fill about 5 meters thick overlaying the intact cemented soil layer. In the 29th of August 2011 following a three-day rainfall a tension crack suddenly occurred on the eastern side of the excavation site. The maximum width of the crack at the surface of the road was 3 cm. This paper summarizes the information on the forensic study which concluded that the rainfall was confined to the fill layer. Therefore drainage system which was located in the cemented soil layer with lower permeability could not function properly. Limit equilibrium analysis correctly predicted the location of the tension crack and the unstable block.

Department(s)

Civil, Architectural and Environmental Engineering

Appears In

International Conference on Case Histories in Geotechnical Engineering

Meeting Name

Seventh Conference

Publisher

Missouri University of Science and Technology

Publication Date

4-29-2013

Document Version

Final Version

Rights

© 2013 Missouri University of Science and Technology, All rights reserved.

Document Type

Article - Conference proceedings

File Type

text

Language

English

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Apr 29th, 12:00 AM May 4th, 12:00 AM

Accumulation of Rainfall in the Permeable Fill Behind a Soil Nail Wall

Chicago, Illinois

TOOBA deep excavation project was conducted in a densely developed area in the North West of Tehran, capital of Iran, to provide space for 4 basement levels for multiple buildings around the already functional TOOBA tower. Besides excavating on 3 sides of TOOBA tower, this project involved excavation to the depths varying from 9 to 28 meters depending on the sloping ground condition. A 5 story school building and a 2 story residential building abut the excavation boundary. Previous experience of constructed soil nail walls in cemented soils of Tehran indicated relatively small wall deformations. Therefore, except for the retaining system of the TOOBA tower, a soil nail wall system was seen appropriate for supporting excavation faces. Wall and ground deformations were monitored during and after construction and the ground around the site was regularly checked for tension cracks. Geotechnical explorations indicated the presence of a disturbed fill about 5 meters thick overlaying the intact cemented soil layer. In the 29th of August 2011 following a three-day rainfall a tension crack suddenly occurred on the eastern side of the excavation site. The maximum width of the crack at the surface of the road was 3 cm. This paper summarizes the information on the forensic study which concluded that the rainfall was confined to the fill layer. Therefore drainage system which was located in the cemented soil layer with lower permeability could not function properly. Limit equilibrium analysis correctly predicted the location of the tension crack and the unstable block.