Location

Chicago, Illinois

Session Start Date

4-29-2013

Session End Date

5-4-2013

Abstract

The soil-structure-interaction of retaining structures is complex and dependent on many factors. In particular excavations in soft soils and urban environments with adjacent buildings are always subjected to deformations which are not fully avoidable. Therefore, numerical analyses can be a powerful tool for predicting the stress path and time dependent deformation behavior of retaining structures in soft soils. But the quality of these numerical predictions is directly related to the used constitutive soil models, the estimation of their material parameters and a realistic simulation of the soil-structure-interaction. The fact that Class-A predictions of the deformation behavior of retaining structures in soft soils tend to be rare highlights the current limitations of numerical analysis. Therefore, the observational method has still to be carried out as superior controlling tool for the construction of retaining structures in soft soils. This contribution stresses the importance of the observational method based on a case history of an 8m deep excavation. The excavation is located in the City Constance in southern Germany and was successfully constructed in deep soft lacustrine clay deposits in 2008. The monitoring program is described in detail with its instrumentation consisting of vertical inclinometers, geodetic deformation points, pore pressure and strain transducers. Furthermore, the concept of the observational method is explained by means of limiting values of threshold for deformations and forces depending on the construction process. Additionally, the evaluation of an a priori numerical analysis which was used for the determination of the threshold values is presented together with the measurement results and a numerical back analysis. The limitations of numerical analysis of retaining structures are shown based on the presented case history and successful application of the observational method. As a result recommendations are presented for numerical simulations of the soil-structure-interaction of excavations in soft soils.

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

Importance of Observational Method in View of Numerical Analyses for Retaning Structures in Soft Soils

Chicago, Illinois

The soil-structure-interaction of retaining structures is complex and dependent on many factors. In particular excavations in soft soils and urban environments with adjacent buildings are always subjected to deformations which are not fully avoidable. Therefore, numerical analyses can be a powerful tool for predicting the stress path and time dependent deformation behavior of retaining structures in soft soils. But the quality of these numerical predictions is directly related to the used constitutive soil models, the estimation of their material parameters and a realistic simulation of the soil-structure-interaction. The fact that Class-A predictions of the deformation behavior of retaining structures in soft soils tend to be rare highlights the current limitations of numerical analysis. Therefore, the observational method has still to be carried out as superior controlling tool for the construction of retaining structures in soft soils. This contribution stresses the importance of the observational method based on a case history of an 8m deep excavation. The excavation is located in the City Constance in southern Germany and was successfully constructed in deep soft lacustrine clay deposits in 2008. The monitoring program is described in detail with its instrumentation consisting of vertical inclinometers, geodetic deformation points, pore pressure and strain transducers. Furthermore, the concept of the observational method is explained by means of limiting values of threshold for deformations and forces depending on the construction process. Additionally, the evaluation of an a priori numerical analysis which was used for the determination of the threshold values is presented together with the measurement results and a numerical back analysis. The limitations of numerical analysis of retaining structures are shown based on the presented case history and successful application of the observational method. As a result recommendations are presented for numerical simulations of the soil-structure-interaction of excavations in soft soils.