Location

New York, New York

Session Start Date

4-13-2004

Session End Date

4-17-2004

Abstract

A new building recently constructed in the centre of the city of Salerno, Italy, comprises a two level underground park with a maximum depth of 8 m below the ground surface and around 5 m below the ground water table. The excavation was carried out within a cast in situ reinforced concrete diaphragm wall, with a thickness of 0.6 m and a length of 18 m. The subsoil profile consists essentially of sand and gravel, with horizontal layers of silt and silty sand. The main silty layer, located near the toe of the diaphragm, appears to be continuous over the excavation area. Other thinner layers are found between the main one and the bottom of the excavation, giving rise to some concern for a possible bottom heave. To eliminate such a risk, the water was pumped from wells with the filter above the main silty layer. The excavation is close to existing buildings and infrastructures; accordingly, a monitoring program has been carried out to control the effects of excavation and dewatering on the surroundings. The horizontal displacements of the diaphragm wall have been measured by means of inclinometers, while vertical displacements of points at the ground surface and on the nearby buildings have been observed by means of precision levelling. Finally, the ground water level has been monitored by standpipe piezometers inside and outside the excavation. The paper reports the results of the measurements and compares them to the previous available experimental evidence.

Department(s)

Civil, Architectural and Environmental Engineering

Appears In

International Conference on Case Histories in Geotechnical Engineering

Meeting Name

Fifth Conference

Publisher

University of Missouri--Rolla

Publication Date

4-13-2004

Document Version

Final Version

Rights

© 2004 University of Missouri--Rolla, All rights reserved.

Document Type

Article - Conference proceedings

File Type

text

Language

English

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Apr 13th, 12:00 AM Apr 17th, 12:00 AM

Monitoring an Excavation in an Urban Area

New York, New York

A new building recently constructed in the centre of the city of Salerno, Italy, comprises a two level underground park with a maximum depth of 8 m below the ground surface and around 5 m below the ground water table. The excavation was carried out within a cast in situ reinforced concrete diaphragm wall, with a thickness of 0.6 m and a length of 18 m. The subsoil profile consists essentially of sand and gravel, with horizontal layers of silt and silty sand. The main silty layer, located near the toe of the diaphragm, appears to be continuous over the excavation area. Other thinner layers are found between the main one and the bottom of the excavation, giving rise to some concern for a possible bottom heave. To eliminate such a risk, the water was pumped from wells with the filter above the main silty layer. The excavation is close to existing buildings and infrastructures; accordingly, a monitoring program has been carried out to control the effects of excavation and dewatering on the surroundings. The horizontal displacements of the diaphragm wall have been measured by means of inclinometers, while vertical displacements of points at the ground surface and on the nearby buildings have been observed by means of precision levelling. Finally, the ground water level has been monitored by standpipe piezometers inside and outside the excavation. The paper reports the results of the measurements and compares them to the previous available experimental evidence.