The Library
Numerical modelling of tunnelling in sand using a state parameter constitutive model
Tools
Yang, Bowen (2018) Numerical modelling of tunnelling in sand using a state parameter constitutive model. PhD thesis, University of Warwick.
|
PDF
WRAP_Theses_Yang_2018.pdf - Submitted Version - Requires a PDF viewer. Download (11Mb) | Preview |
Official URL: http://webcat.warwick.ac.uk/record=b3453568~S15
Abstract
During urbanisation, tunnelling in soft ground is an inevitable issue. In the last hundred years, the tunnelling techniques have been developed considerably so that the excavation speed has considerably increased; the tunnel diameter becomes so large that a single tunnel is able to contain dual direction traffic; the settlement influence induced by tunnelling has been reduced by magnitudes. On the other hand, our understanding of soft ground has improved less relative to the improvements of tunnelling techniques, due to complexity of the ground formation and difficulty of obtaining detailed data of the ground.
Tunnelling in sand has drawn less research interest in recent decades compared to tunnelling in clay. However tunnelling is ubiquitous in many cities that don't have regular stiff clay ground. This thesis focuses on numerical predictions of ground response induced by tunnelling in sand. Two main topics of research are covered in this study, namely constitutive behaviour of sand and numerical modelling of tunnel volume loss induced ground response.
An existing constitutive sand model - Norsand is used as the base theory of the new developed sand model. Small strain stiffness, non-linear elasticity during unloading and the flow rule during softening are either improved or added in the proposed sand model compared to Norsand. Laboratory data of drained and undrained triaxial compression tests on different types of sands are used for validation of the proposed model. Numerical simulation of triaxial testing demonstrates good agreement with the test data in both small and large strain situations.
The proposed model is implemented into the commercial finite element geotechnical analysis software Plaxis 3D for numerical modelling of a centrifuge tunnelling prototype carried out in sand. A standard constitutive soil model - Hardening Soil is also applied in the numerical modelling for comparison. Numerical ground movement results from both soil models illustrate good agreement with the centrifuge test result around small – medium tunnel deformation level. However the dilation – contraction behaviour of sand in all deformation levels is clearly demonstrated in the results calculated by the proposed model while the Hardening Soil model hardly models this feature.
This research proposed a new developed sand model that can describe the dilation-contraction behaviour and the small strain stiffness of sand, and demonstrated the capability of predicting the ground response induced by tunnelling in sand using this model.
Item Type: | Thesis (PhD) | ||||
---|---|---|---|---|---|
Subjects: | H Social Sciences > HT Communities. Classes. Races T Technology > TA Engineering (General). Civil engineering (General) |
||||
Library of Congress Subject Headings (LCSH): | Tunnels, Urbanization, Excavation, Sand | ||||
Official Date: | January 2018 | ||||
Dates: |
|
||||
Institution: | University of Warwick | ||||
Theses Department: | School of Engineering | ||||
Thesis Type: | PhD | ||||
Publication Status: | Unpublished | ||||
Supervisor(s)/Advisor: | Bloodworth, Alan ; Jones, Benoit | ||||
Format of File: | |||||
Extent: | xxi, 242 leaves: illustrations, charts, plates | ||||
Language: | eng |
Request changes or add full text files to a record
Repository staff actions (login required)
View Item |
Downloads
Downloads per month over past year