Projects per year
Abstract
The uncertainties inherent in each geological and ground model naturally lead to
uncertainties in stability analyses of geotechnical structures. Only when a consistent
procedure is used for the quantification of the geotechnical variability, the probability of
instability of a tunnel can be assessed.
A consistent procedure for the determination of the rock mass behaviour as a result of
the tunnel excavation has been developed and will be outlined in the presentation. A
distinct geological model, the selection of relevant parameters and a systematic and
quantitative rock mass characterization form the basis for all further probabilistic
evaluations. After the definition of key parameters and factors of influence it is
important to determine the spread of parameters and to quantify the possible variations
of the geological model. In a first step rock type specific key parameters are selected.
The evaluation of the rock mass properties then leads to the identification of rock mass
types. The next step includes the assignment of rock mass types to the different sections
along the tunnel. Then the rock mass behaviour in each section as a result of the
excavation is evaluated considering the rock mass properties and influencing factors,
like stresses, discontinuity orientation, ground water, etc.
The probabilistic processing of the input data results in a quantification of the
probability of occurrence of the single rock mass behaviour types. By assigning a
support concept to each behaviour type the system behaviour then is evaluated and
compared to the requirements of stability and serviceability. As also the behaviour
within a behaviour type has a certain spread, for example magnitude of displacements,
size of instable blocks etc., this spread has to be considered in the stability analysis. The
models used for the analysis in terms of sophistication depend on the phase of the
project, and on the environmental constraints. Relatively simple closed form solutions
may satisfy the requirements in early project phases or in less sensitive areas, while
numerical models will have to be used in highly sensitive situations. Examples of
analyses will be shown.
uncertainties in stability analyses of geotechnical structures. Only when a consistent
procedure is used for the quantification of the geotechnical variability, the probability of
instability of a tunnel can be assessed.
A consistent procedure for the determination of the rock mass behaviour as a result of
the tunnel excavation has been developed and will be outlined in the presentation. A
distinct geological model, the selection of relevant parameters and a systematic and
quantitative rock mass characterization form the basis for all further probabilistic
evaluations. After the definition of key parameters and factors of influence it is
important to determine the spread of parameters and to quantify the possible variations
of the geological model. In a first step rock type specific key parameters are selected.
The evaluation of the rock mass properties then leads to the identification of rock mass
types. The next step includes the assignment of rock mass types to the different sections
along the tunnel. Then the rock mass behaviour in each section as a result of the
excavation is evaluated considering the rock mass properties and influencing factors,
like stresses, discontinuity orientation, ground water, etc.
The probabilistic processing of the input data results in a quantification of the
probability of occurrence of the single rock mass behaviour types. By assigning a
support concept to each behaviour type the system behaviour then is evaluated and
compared to the requirements of stability and serviceability. As also the behaviour
within a behaviour type has a certain spread, for example magnitude of displacements,
size of instable blocks etc., this spread has to be considered in the stability analysis. The
models used for the analysis in terms of sophistication depend on the phase of the
project, and on the environmental constraints. Relatively simple closed form solutions
may satisfy the requirements in early project phases or in less sensitive areas, while
numerical models will have to be used in highly sensitive situations. Examples of
analyses will be shown.
| Original language | English |
|---|---|
| Title of host publication | Föredrag vid Bergmekanikdag i Stockhokm 17 mars 2004 |
| Subtitle of host publication | Papers presented at Rock Mechanics Meeting in Stockholm March 17, 2004 |
| Place of Publication | Stockholm |
| Number of pages | 20 |
| Publication status | Published - 2004 |
Fingerprint
Dive into the research topics of 'Probabilistic Assessment of Rock Mass Behaviour as Basis for Stability Analyses of Tunnels'. Together they form a unique fingerprint.Projects
- 2 Finished
-
A Hierarchical Rock Mass Characterization for Tunnel Design & A Deterministic and Probabilistic Approach
Schubert, W. (Principal Investigator (PI)) & Goricki, A. (Co-Investigator (CoI))
1/01/00 → 1/01/10
Project: Research project
-
Modelling of Rock Mass Behaviour
Radoncic, N. (Co-Investigator (CoI)), Pilgerstorfer, T. (Co-Investigator (CoI)), Schubert, W. (Principal Investigator (PI)) & Seidl, C. (Co-Investigator (CoI))
1/12/92 → 31/12/23
Project: Research project