Evaluation of the differences in characterization and classification of the rock mass quality : A comparison between pre-investigation, engineering geological forecast and tunnel mapping in the Northern Link project and the Cityline project

In the construction of a tunnel, the characterization of the rock mass is performed in three different steps, in the pre-investigations, in the engineering geological forecast and in the tunnel mapping during construction. There has in previous work been observed that discrepancies exist between the...

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Main Author: Benhalima, Mehdi
Format: Others
Language:English
Published: KTH, Jord- och bergmekanik 2016
Subjects:
Online Access:http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-195743
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spelling ndltd-UPSALLA1-oai-DiVA.org-kth-1957432016-11-11T05:08:27ZEvaluation of the differences in characterization and classification of the rock mass quality : A comparison between pre-investigation, engineering geological forecast and tunnel mapping in the Northern Link project and the Cityline projectengBenhalima, MehdiKTH, Jord- och bergmekanik2016Characterizationclassificationrock mass qualityengineering geological forecasttunnel mappingdiscontinuitiesQ-systemNorthern LinkIn the construction of a tunnel, the characterization of the rock mass is performed in three different steps, in the pre-investigations, in the engineering geological forecast and in the tunnel mapping during construction. There has in previous work been observed that discrepancies exist between the results from these different steps, with a tendency to assign poorer rock mass quality in the tunnel mapping than in the pre-investigations and in the engineering geological forecast. One example is the work done by Kjellström [1] on the Cityline where the divergence in rock mass quality was analyzed between the different steps. If a divergence exists between the engineering geological forecast and the actual conditions observed in the tunnel mapping, it will influence both planning and budget. It is therefore important that the engineering geological forecast is as close as possible to the actual rock mass conditions in the field. The aim of this thesis was, using the case study of the Northern Link, to analyze those discrepancies in the rock mass quality estimated in the characterization and in the classification between the mapping of drill cores, the engineering geological forecast and the tunnel mapping thus complementing the work by Kjellström [1]. The aim was also identifying which parameters included in the Q-system that causes these discrepancies The analysis of the results showed that it is difficult to make the engineering geological forecast and the actual mapping match for every single meter, but that the overall correlation between them was good. The methodology used in the characterization and classification in the different phases (drill-core mapping, engineering geological forecast, tunnel mapping) may to some extent explain this divergence. The parameters Jr, Jn and Ja, included in the Q-system were the ones identified as having the largest influence on the discrepancies. In future work, it is recommended that focus is given on these parameters. A way to improve future engineering geological forecast for tunnel contracts would be to have a better follow up of the engineering geological forecast and to have standardized guidelines on how to assess clearly the value of the Q parameters in each phase (for the drill cores as well as for the actual mapping). The reduction of those differences would then lead to a better planning and budget management in future tunnel projects in Sweden. Student thesisinfo:eu-repo/semantics/bachelorThesistexthttp://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-195743Examensarbete Jord- och bergmekanik, 1652-599X ; 16:11application/pdfinfo:eu-repo/semantics/openAccess
collection NDLTD
language English
format Others
sources NDLTD
topic Characterization
classification
rock mass quality
engineering geological forecast
tunnel mapping
discontinuities
Q-system
Northern Link
spellingShingle Characterization
classification
rock mass quality
engineering geological forecast
tunnel mapping
discontinuities
Q-system
Northern Link
Benhalima, Mehdi
Evaluation of the differences in characterization and classification of the rock mass quality : A comparison between pre-investigation, engineering geological forecast and tunnel mapping in the Northern Link project and the Cityline project
description In the construction of a tunnel, the characterization of the rock mass is performed in three different steps, in the pre-investigations, in the engineering geological forecast and in the tunnel mapping during construction. There has in previous work been observed that discrepancies exist between the results from these different steps, with a tendency to assign poorer rock mass quality in the tunnel mapping than in the pre-investigations and in the engineering geological forecast. One example is the work done by Kjellström [1] on the Cityline where the divergence in rock mass quality was analyzed between the different steps. If a divergence exists between the engineering geological forecast and the actual conditions observed in the tunnel mapping, it will influence both planning and budget. It is therefore important that the engineering geological forecast is as close as possible to the actual rock mass conditions in the field. The aim of this thesis was, using the case study of the Northern Link, to analyze those discrepancies in the rock mass quality estimated in the characterization and in the classification between the mapping of drill cores, the engineering geological forecast and the tunnel mapping thus complementing the work by Kjellström [1]. The aim was also identifying which parameters included in the Q-system that causes these discrepancies The analysis of the results showed that it is difficult to make the engineering geological forecast and the actual mapping match for every single meter, but that the overall correlation between them was good. The methodology used in the characterization and classification in the different phases (drill-core mapping, engineering geological forecast, tunnel mapping) may to some extent explain this divergence. The parameters Jr, Jn and Ja, included in the Q-system were the ones identified as having the largest influence on the discrepancies. In future work, it is recommended that focus is given on these parameters. A way to improve future engineering geological forecast for tunnel contracts would be to have a better follow up of the engineering geological forecast and to have standardized guidelines on how to assess clearly the value of the Q parameters in each phase (for the drill cores as well as for the actual mapping). The reduction of those differences would then lead to a better planning and budget management in future tunnel projects in Sweden.
author Benhalima, Mehdi
author_facet Benhalima, Mehdi
author_sort Benhalima, Mehdi
title Evaluation of the differences in characterization and classification of the rock mass quality : A comparison between pre-investigation, engineering geological forecast and tunnel mapping in the Northern Link project and the Cityline project
title_short Evaluation of the differences in characterization and classification of the rock mass quality : A comparison between pre-investigation, engineering geological forecast and tunnel mapping in the Northern Link project and the Cityline project
title_full Evaluation of the differences in characterization and classification of the rock mass quality : A comparison between pre-investigation, engineering geological forecast and tunnel mapping in the Northern Link project and the Cityline project
title_fullStr Evaluation of the differences in characterization and classification of the rock mass quality : A comparison between pre-investigation, engineering geological forecast and tunnel mapping in the Northern Link project and the Cityline project
title_full_unstemmed Evaluation of the differences in characterization and classification of the rock mass quality : A comparison between pre-investigation, engineering geological forecast and tunnel mapping in the Northern Link project and the Cityline project
title_sort evaluation of the differences in characterization and classification of the rock mass quality : a comparison between pre-investigation, engineering geological forecast and tunnel mapping in the northern link project and the cityline project
publisher KTH, Jord- och bergmekanik
publishDate 2016
url http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-195743
work_keys_str_mv AT benhalimamehdi evaluationofthedifferencesincharacterizationandclassificationoftherockmassqualityacomparisonbetweenpreinvestigationengineeringgeologicalforecastandtunnelmappinginthenorthernlinkprojectandthecitylineproject
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