“SINTEF-TriPOD” in underground design – A demonstration for two projects in Norway

Many rock engineering projects today may face rock mechanics challenges such as particularly complicated profile or excavation plan, located near to existing infrastructure and thus pose a high risk to such structures, and complicated geological conditions. In such situation, there may be no similar existing experience to lean on. Thus, empirical methods have limitations and uncertainties in such cases. Therefore, SINTEF has developed a rock engineering tool to deal with the challenges. The tool is a combination of Investigation, Numerical modelling, and Monitoring. We use the term “SINTEF-TriPOD” for the methodology, and through projects it has proved to be a reliable tool. This paper presents the application of the SINTEF-TriPOD for two important infrastructure projects in Oslo, Norway, which are Follo Line metro project (4 billion USD) and a fresh water supply project (approximately 1.2 billion USD).publishedVersio

Samfunnet trenger undergrunnen mer enn noen gang

Vi i anleggsnæringen må bli bedre på å fremsnakke oss selv og de løsningene vi har på store samfunnsutfordringer.publishedVersio

Validity of the NTNU Prediction Model for D&B Tunnelling

The Norwegian University of Science and Technology (NTNU) has since the early 1970s published prediction models for estimated production rates, time consumption, and costs for rock works. Since the early development of the NTNU models the tunnelling industry has continuously improved and the models have been updated on several occasions. The NTNU models are presently being updated to better fit the modern tunnelling trends in Norway. The current prediction model for D&B blast design is in this research paper compared with new data from thirteen recent Norwegian tunnel projects. The paper demonstrates that the empirical methodology behind the prediction model is still highly relevant, but some further improvements and additional empirical relations are suggested to enable the model to better cope with the recent 16 years of development in technology, equipment, contractual-issues and blast design. The new datasets show that modern D&B tunnelling employ more drill holes and specific charging per blast round than before. The current NTNU model thus under-predicts the actual tunnelling performance in the blast design. Some suggestions are made for further improving the model, where the updated drill length, the contour requirements, and the tendency to including the longitudinal ditches into the main blast are suggested as the main reasons for the disparity in drill hole numbers. Yet, the current trend in specific charging seem to have doubled since the early 2000s and cannot be explained by the increase in drill holes alone. Further development ought to be included in the blastability index (SPR) so that geological conditions that are on the extreme side of poor blastability can be properly accounted for in the blast design.publishedVersio

Proceedings of the Institution of Civil Engineers

The Faroe Islands north of Scotland has a disproportionally large number of road tunnels. In addition to 44 km of existing tunnels, two further undersea tunnels totalling 22 km will be completed by 2023. A further 30 km undersea crossing is planned, providing nearly 2 m of tunnel for each of the 50 000 inhabitants. This paper describes the country’s recent, current and proposed subsea tunnelling projects. When eventually completed they will reduce journey times between the 18 major islands from up to a day to no more than a few hours’ drive.publishedVersio

Grønn anleggssektor for bærekraftig infrastruktur

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Subsea road tunnels in the Faroe Islands

The Faroe Islands north of Scotland has a disproportionally large number of road tunnels. In addition to 44 km of existing tunnels, two further undersea tunnels totalling 22 km will be completed by 2023. A further 30 km undersea crossing is planned, providing nearly 2 m of tunnel for each of the 50 000 inhabitants. This paper describes the country’s recent, current and proposed subsea tunnelling projects. When eventually completed they will reduce journey times between the 18 major islands from up to a day to no more than a few hours’ drive

Choice of execution model for tunnels

Forfatterne har ved en rekke anledninger vært involvert i å evaluere metodevalg for tunnelprosjekter. Ofte er situasjonen slik at en byggherre har kommet dithen at man av ulike årsaker må gjøre en evaluering av valg av drivemetode for et prosjekt. Ofte kommer man dit veldig sent i et prosjekt, når de fleste beslutninger er tatt, prosjektet er mer eller mindre bundet opp i forhold til trasé, tilkomst- og påhuggsmuligheter osv. Ofte blir da en slik evaluering bare en regneøvelse på kostnads- og tidsestimat, med svært få friheter til å gjøre optimaliseringer for de ulike drivemetodene. Ofte har frontene i slike sammenhenger vært steile, og det har fremkommet nærmest som om det er en skyttergravskrig mellom de som favoriserer TBM og de som favoriserer B&S (boring og sprengning). Det er en lite fruktbar utvikling uten muligheter for teknisk og faglig utvikling i bransjen. Slike vurderinger må gjøres ved å snu hver eneste stein fra starten i et prosjekt for å finne muligheter for ulike drivemetoder. Vi har derfor kalt foreliggende artikkel «Valg av gjennomføringsmodell for tunneler» fordi det er det det dreier seg om heller enn valg av drivemetode med et avkortet mandat knyttet til muligheter og begrensninger med konvensjonell driving eller TBM.The authors of the article have both been involved and engaged on a number of occasions to make an evaluation of the choice of excavation method for tunnel projects. Often the situation is such that a developer has reached the point where, for various reasons, an evaluation of the choice of tunnelling method for a project needs to be made. You often get there very late in a project where most decisions have been made, the project is more or less tied up in relation to the alignment, access and adit possibilities, etc. Such an evaluation often becomes only a calculation exercise on cost and time estimates, with very few freedoms to make optimizations for the various drive methods. Often the fronts in such contexts have been steep and it has appeared almost as if there is a form of trench warfare between those who favour TBM and those who favour drilling and blasting. It is an unfruitful development without much technical and professional progress in the industry. Such assessments must be made by turning over every stone in a project to find elements for different driving methodspublishedVersio

Development of an algorithm to detect hydraulic jacking in high pressure rock mass grouting and introduction of the PF index

Pre-excavation rock mass grouting is a common procedure for reducing water ingress into tunnels during construction in Norwegian tunnelling. The level of grouting pressure is a disputed subject and the knowledge of how the rock mass responds to the high pressure and how this inflicts on the grouting results is sparse and little investigated. For this reason, it is of interest to use data from high pressure grouting performed in Norwegian projects to investigate these matters. This paper presents the development of a method for identifying hydraulic jacking during rock mass grouting and the making of an algorithm to perform computerized detection of hydraulic jacking in grouting logs. The algorithm is the base for a larger study, where screening for hydraulic jacking is performed in over hundred grouting rounds, distributed on several Norwegian tunnels excavated in rock mass. The relation between grout flow and grouting pressure has shown to be vital for the understanding of the grouting progress and events occurring during the grouting. Interpretation of pressure and flow as two separate variables, which are affected by aliasing, caused by low and irregular sampling frequency is a challenging task, and it was found to be helpful to create a parameter to represent this relationship, named the PF index (Pressure Flow index). This parameter has also shown to be useful in other applications such as monitoring the grouting progress on site

Subsea tunnel linking Föglö with the main island in Åland

The paper describes a well considered subsea road tunnel in Åland, Finland which will hopefully start in the very near future. The paper describes partly the socio-economics and public benefits of such a project in Åland and partly some technical aspects of designing and constructing road tunnels under the sea to connect land masses. The tunnel is expected to be constructed along the lines of similar rock tunnels being constructed and entered into successful operation in many of the Scandinavian /Nordic countries. More important though is the vital role such a project will serve for the society in Åland. The project is not one that serves millions of people in busy mega cities – still it is a pleasure to see a mega project for a small community mature, starting from a sketchy plan made by individual enthusiasts to a solid plan for a multi-million Euro investment