Behaviour of diaphragm walls in clay prior to collapse
Behaviour of diaphragm walls in clay prior to collapse
Centrifuge model tests have been used in an attempt to gain a coherent view of the soil-structure interaction behaviour following the excavation of soil in front of a pre-constructed wall. Excavation was simulated by the removal of a suitably heavy fluid from a preformed cavity. The broad replication of stress magnitudes and stress paths permitted the full representation of wall deformation, soil strain and swelling, completing a 50 year full-scale lifespan in under 24 hours of continuous centrifuging. Measurements were made of soil displacement vectors, pore water pressures, wall displacements and bending moments together with forces in props when they were present. These have made possible the validation of simplified ‘geostructural mechanisms’ which offer the same degree of advantage to the designer as does the idealization of beam behaviour encapsulated in engineer's beam theory. A serviceability criterion for soil or wall displacements can be entered into simplified admissible strain fields appropriate to the kinematic constraints so that the effective mobilized soil strain in the major zones of soil deformation can be deduced. This can lead, through triaxial or plane strain test data, to the selection of a mobilized soil strength and thence to an equilibrium analysis of the wall, from which unknowns such as the required wall penetration and bending strength and the required prop force can be determined. This approach leads to the evaluation of a design in terms of the chosen displacement criterion and avoids the question of defining or calculating a ‘factor of safety’. Safety can be judged against separate collapse criteria, linked to the establishment of severe but realistic combinations of influences.
soil–structure interaction, diaphragm walls, centrifuge modelling, deformation, time dependence, design
167-189
Bolton, M.D.
16dbae03-7966-48fd-ae56-41966133e588
Powrie, W.
600c3f02-00f8-4486-ae4b-b4fc8ec77c3c
June 1988
Bolton, M.D.
16dbae03-7966-48fd-ae56-41966133e588
Powrie, W.
600c3f02-00f8-4486-ae4b-b4fc8ec77c3c
Abstract
Centrifuge model tests have been used in an attempt to gain a coherent view of the soil-structure interaction behaviour following the excavation of soil in front of a pre-constructed wall. Excavation was simulated by the removal of a suitably heavy fluid from a preformed cavity. The broad replication of stress magnitudes and stress paths permitted the full representation of wall deformation, soil strain and swelling, completing a 50 year full-scale lifespan in under 24 hours of continuous centrifuging. Measurements were made of soil displacement vectors, pore water pressures, wall displacements and bending moments together with forces in props when they were present. These have made possible the validation of simplified ‘geostructural mechanisms’ which offer the same degree of advantage to the designer as does the idealization of beam behaviour encapsulated in engineer's beam theory. A serviceability criterion for soil or wall displacements can be entered into simplified admissible strain fields appropriate to the kinematic constraints so that the effective mobilized soil strain in the major zones of soil deformation can be deduced. This can lead, through triaxial or plane strain test data, to the selection of a mobilized soil strength and thence to an equilibrium analysis of the wall, from which unknowns such as the required wall penetration and bending strength and the required prop force can be determined. This approach leads to the evaluation of a design in terms of the chosen displacement criterion and avoids the question of defining or calculating a ‘factor of safety’. Safety can be judged against separate collapse criteria, linked to the establishment of severe but realistic combinations of influences.
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Published date: June 1988
Keywords:
soil–structure interaction, diaphragm walls, centrifuge modelling, deformation, time dependence, design
Organisations:
Civil Engineering & the Environment
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Local EPrints ID: 75627
URI: http://eprints.soton.ac.uk/id/eprint/75627
ISSN: 0016-8505
PURE UUID: 6ab358c3-900d-40f8-acd0-2fe649b1850d
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Date deposited: 11 Mar 2010
Last modified: 14 Mar 2024 02:37
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Author:
M.D. Bolton
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