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Abstract
One of the major drawbacks of two-dimensional approaches in underground excavation design is the (mostly) inadequate modelling of the effects of the face advance. The amount of pre-displacements and the evolution of the displacements towards
their final value are generally roughly estimated. On the other hand, 3D calculations pose a much greater modelling and evaluation challenge, and can be conducted only by the usage of numerical methods.
The work presented in this publication is directed towards narrowing of this gap. It concerns the determination of the displacement evolution in an elasto-plastic, Mohr-Coulomb medium under hydrostatic primary stress state. 3D numerical simulations with FLAC 3D have been used to generate the displacement evolutions for various parameter combinations. The
parameters have been chosen in such way that they form a regular grid in a co-ordinate system spanned by the friction angle and a unit-less variable defined as the ratio between the depth of failure and the tunnel radius. Utilizing the closed-form solution by Feder and Arwanitakis, the equivalent fictitious support pressure was calculated from the provided displacement paths, thus allowing the establishment of three interpolation relationships. The development of the fictitious support pressure can be directly derived from these interpolation relationships, hence predicting both the displacement development and the amount of pre-
relaxation of the ground.
The effects of lining installation can be easily incorporated in this model by superposing the fictitious support pressure with the mobilized support pressure, while obeying the displacement compatibility between the liner and the rock mass. Both the solution
scheme and its validation are presented in this paper, together with an empirical relationship depicting the rheological properties of shotcrete. The combination of these relationships enables an approximate estimation of the displacement development with
installed shotcrete support and of the associated shotcrete utilisation ratio, hence allowing very fast assessment of the system behaviour in given tunnelling conditions.
The results obtained with the application of the presented method are discussed, depicting selected tunnelling scenarios and their impact on the lining displacement development and associated utilisation ratio
their final value are generally roughly estimated. On the other hand, 3D calculations pose a much greater modelling and evaluation challenge, and can be conducted only by the usage of numerical methods.
The work presented in this publication is directed towards narrowing of this gap. It concerns the determination of the displacement evolution in an elasto-plastic, Mohr-Coulomb medium under hydrostatic primary stress state. 3D numerical simulations with FLAC 3D have been used to generate the displacement evolutions for various parameter combinations. The
parameters have been chosen in such way that they form a regular grid in a co-ordinate system spanned by the friction angle and a unit-less variable defined as the ratio between the depth of failure and the tunnel radius. Utilizing the closed-form solution by Feder and Arwanitakis, the equivalent fictitious support pressure was calculated from the provided displacement paths, thus allowing the establishment of three interpolation relationships. The development of the fictitious support pressure can be directly derived from these interpolation relationships, hence predicting both the displacement development and the amount of pre-
relaxation of the ground.
The effects of lining installation can be easily incorporated in this model by superposing the fictitious support pressure with the mobilized support pressure, while obeying the displacement compatibility between the liner and the rock mass. Both the solution
scheme and its validation are presented in this paper, together with an empirical relationship depicting the rheological properties of shotcrete. The combination of these relationships enables an approximate estimation of the displacement development with
installed shotcrete support and of the associated shotcrete utilisation ratio, hence allowing very fast assessment of the system behaviour in given tunnelling conditions.
The results obtained with the application of the presented method are discussed, depicting selected tunnelling scenarios and their impact on the lining displacement development and associated utilisation ratio
| Original language | English |
|---|---|
| Title of host publication | New Horizons in Rock Mechanics - Developments and Applications - ISRM International Symposium 2008/5th Asian Rock Mechanics Symposium (ARMS5) |
| Place of Publication | Red Hook, NY |
| Publisher | Curran |
| Pages | 809-818 |
| Volume | 2 |
| ISBN (Print) | 9781617823527 |
| Publication status | Published - 2008 |
| Event | 5th Asian Rock Mechanics Symposium: ARMS5 2008 - Tehran, Iran, Islamic Republic of Duration: 24 Nov 2008 → 26 Nov 2008 |
Conference
| Conference | 5th Asian Rock Mechanics Symposium |
|---|---|
| Abbreviated title | ARMS 2008 |
| Country/Territory | Iran, Islamic Republic of |
| City | Tehran |
| Period | 24/11/08 → 26/11/08 |
Treatment code (Nähere Zuordnung)
- Application
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Dive into the research topics of 'Prediction of displacements in tunnels'. Together they form a unique fingerprint.Projects
- 1 Finished
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Prediction of Displacements in Tunnelling
Radoncic, N. (Co-Investigator (CoI)), Pilgerstorfer, T. (Co-Investigator (CoI)), Seidl, C. (Co-Investigator (CoI)) & Schubert, W. (Principal Investigator (PI))
1/12/96 → 31/12/23
Project: Research project