A platform for research: civil engineering, architecture and urbanism
A platform for research: civil engineering, architecture and urbanism
Nicoll highway collapse: Evaluation of geotechnical factors affecting design of excavation support system
This paper summarizes the site characterization, selection of soil parameters and analyses of soil-structure interaction that affected the design of the support system for the Circle Line Stage 1 excavations at contract C824, adjacent to the Nicoll Highway. Features of the local stratigraphy included a buried channel in the underlying Old Alluvium which affected directly the installation of perimeter diaphragm wall panels. Surface settlements and pore pressures measured prior to construction strongly suggest on-going consolidation of the Marine Clay due to land reclamation in the 1970's. From the evidence available, the authors concluded that the lower Marine Clay unit was underconsolidated resulting in a relatively low undrained shear strength of the clay in relation to the total overburden pressure. Uncertainties existed in drainage conditions in the Old Alluvium and despite extensive post-failure investigations, the installed locations, behavior and mass properties of jet grout pile-rafts remain highly uncertain. The original analysis of soil-structure interaction was carried out using nonlinear finite element methods with linearly-elastic, Mohr-Coulomb (MC) models to represent the soil behavior. The use of this soil model together with drained effective stress strength parameters (c',Phi'), in an undrained setting, greatly overestimated the undrained shear strength of the Marine Clay in the original design leading to a serious underestimation of computed wall deflections, bending moments and the mobilization of forces in the JGP pile-rafts.
Nicoll highway collapse: Evaluation of geotechnical factors affecting design of excavation support system
This paper summarizes the site characterization, selection of soil parameters and analyses of soil-structure interaction that affected the design of the support system for the Circle Line Stage 1 excavations at contract C824, adjacent to the Nicoll Highway. Features of the local stratigraphy included a buried channel in the underlying Old Alluvium which affected directly the installation of perimeter diaphragm wall panels. Surface settlements and pore pressures measured prior to construction strongly suggest on-going consolidation of the Marine Clay due to land reclamation in the 1970's. From the evidence available, the authors concluded that the lower Marine Clay unit was underconsolidated resulting in a relatively low undrained shear strength of the clay in relation to the total overburden pressure. Uncertainties existed in drainage conditions in the Old Alluvium and despite extensive post-failure investigations, the installed locations, behavior and mass properties of jet grout pile-rafts remain highly uncertain. The original analysis of soil-structure interaction was carried out using nonlinear finite element methods with linearly-elastic, Mohr-Coulomb (MC) models to represent the soil behavior. The use of this soil model together with drained effective stress strength parameters (c',Phi'), in an undrained setting, greatly overestimated the undrained shear strength of the Marine Clay in the original design leading to a serious underestimation of computed wall deflections, bending moments and the mobilization of forces in the JGP pile-rafts.
Nicoll highway collapse: Evaluation of geotechnical factors affecting design of excavation support system
Schadensfall Nicoll Highway: Ermittlung der geotechnischen Faktoren mit Einfluss auf die Aushubarbeiten
Whittle, A.J. (author) / Davies, R.V. (author)
2007
20 Seiten, 14 Bilder, 21 Quellen
Conference paper
English
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