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  • 1.
    Ittner, Henrik
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi. Svensk Kärnbränslehantering AB.
    Olsson, Mats
    EDZ Consulting AB.
    Johansson, Daniel
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Schunnesson, Håkan
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Multivariate evaluation of blast damage from emulsion explosives in tunnels excavated in crystalline rock2019Ingår i: Tunnelling and Underground Space Technology, ISSN 0886-7798, E-ISSN 1878-4364, Vol. 85, s. 331-339Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Blast damage in tunnels is usually regulated in Swedish infrastructure contracts as it can influence the quality and lifecycle cost for tunneling projects. The topic is important for underground constructions with a long operation period such as tunnels for public transport, permanent access tunnels in mines or underground repositories for nuclear waste. This paper aims to evaluate the influence of design and geology variables on the resulting blast fracture length and frequency by means of multivariate data analysis. The analysis was based on data from five field investigations carried out at tunnel sites in Sweden and Finland where emulsion explosives were used. Data was compiled and analyzed using Principal Component Analysis (PCA). Charge concentration was found to be the most influential design variable and hole spacing had limited influence on blast fracturing. Results from the PCA suggest that blast fractures length could be dependent also on geology and natural fractures. Three main groups of fracture patterns were identified, one group with relatively few and short blast fractures, a group with several longer blast fractures and a group with few or a single long blast fracture. The result shows differences in fracture length between the column and bottom charge part of the contour holes, with blast fracture lengths up to approx. 40 cm for the column charge and up to approx. 60 cm for the bottom charge.

  • 2.
    Ittner, Henrik
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi. Svensk Kärnbränslehantering AB.
    Excavation damage from blasting with emulsion explosives: Quality control and macro fracturing in the remaining rock2018Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Excavation damage is usually regulated in Swedish infrastructure tunnel contracts as it can influence the quality and lifecycle cost for tunneling projects. The topic is important for underground constructions with a long operation period such as tunnels for public transport, permanent access tunnels in mines or underground repositories for nuclear waste. In competent crystalline rock, excavation damage is often simplified to macro fractures induced by blasting as this has the most significant impact on the remaining rock. Blasting in Scandinavian tunneling projects is mostly conducted with pumpable emulsion explosives and a good result is often dependent on control of the charging process, i.e. that the explosives are charged according to the blast design.

    This thesis is based on data from five field investigations carried out in Sweden and Finland. In addition, data from a case study on quality control and documentation in a tunnel excavation project in Äspö Hard Rock Laboratory (HRL) is also included. Data on blast fracture length and frequency have been compiled from all sites, where emulsion explosives were used. The sites include experimental tunnels, a road tunnel, an underground depot for subway trains and a wastewater tunnel. Data from the field investigations have been analyzed using statistical methods including statistical hypothesis test and multivariate data analysis by means of Principal Component Analysis (PCA).

    The evaluation method gives indications as to how blast design and geology influence the development of blast fractures. Charge concentration was found to be the most influential design variable and simultaneous initiation of contour holes (delay time <1 ms) gave shorter blast fractures with a longest blast fracture of approx. 25 cm compared to approx. 40 cm from pyrotechnical initiation. However, the delay time had limited influence on the number of blast fractures in the remaining rock. Results from the PCA suggest that blast fractures length could be dependent also on geology.

    Three main groups of fracture patterns were identified, one group with relatively few and short fractures, a group with several longer blast fractures and a group with few or a single long blast fracture. The result shows differences in fracture length between the column and bottom charge part of the contour holes, with blast fracture lengths up to approx. 40 cm for the column charge and up to approx. 60 cm for the bottom charge.

    The case study showed that good precision in charging with string emulsion can be achieved and documented using modern logger technology in drilling and charging equipment. However, the methods applied for evaluation of charging precision as well as documentation require manual processing and interpretation of data. Further development of the logger systems and processing software is needed in order to follow up logged amounts of emulsion explosive during production.

  • 3.
    Ittner, Henrik
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi. Svensk Kärnbränslehantering AB.
    Wernby, Bernt
    Forcit Sweden AB.
    Bouvin, Anders
    Forcit Sweden AB.
    Husaas, Tarald
    Forcit Norway AS.
    Investigation of blast fractures from mechanized charging with emulsion during tunnelling2017Ingår i: Proceedings of the World Tunnel Congress 2017: Surface challenges – Underground solutions, 2017, s. 1542-1549Konferensbidrag (Refereegranskat)
    Abstract [en]

    Aquality factor that can decrease the need for rock reinforcement andmaintenance in underground facilities is limitation of blast damage in thetunnel contour. This paper presents results from a project initiated by the SKBand Forcit Sweden AB to investigate the extent of blast damage from emulsionexplosives. The investigations were conducted at two tunnel sites in Sweden,Äspö HRL and a wastewater tunnel under construction in Kista. The tunnels wereexcavated with the same technology for mechanized charging but with differentpurposes and quality requirements. Results from the presented project includefracture mapping of the excavated slots, blast fracture length and frequency,calculated charge concentration for mapped blasting halfpipes in the slots atÄspö HRL and measurements of VOD (velocity of detonation) in the wastewatertunnel in Kista and the Kankberg mine.

  • 4.
    van Eldert, Jeroen
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Ittner, Henrik
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Schunnesson, Håkan
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Johansson, Daniel
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Evaluation of Alternative Techniques for Excavation Damage Characterization2016Ingår i: ITA-AITES World Tunnel Congress 2016, WTC 2016 / [ed] Society for Mining, Metallurgy & Exploration (SME), United States of America, 2016, Vol. 2, s. 1168-1177Konferensbidrag (Refereegranskat)
    Abstract [en]

    Numerous aspects of underground construction, from structural stability to construction costs, depended on the tunnel quality, including blast damage and the Excavation Damage Zone. Accurately quantifying the extent and severity of damaged rock is a problem. Recent technical developments in the field of Measurement While Drilling (MWD), including software for on-board logging and on-site analysis, have shown potential for rock-mass characterization. Ground Penetrating Radar (GPR) and P-wave velocity measurement have also improved and show similar potential. This paper explores the use of MWD, GPR and P-wave velocity measurements and uses them in techniques for excavation damage characterization and prediction. The paper is based on data collected from a small underground wastecollection site in central Stockholm, Sweden. The data is correlated against rock-mass characteristics and their responses are evaluated. Results indicate potential for excavation damage characterization for all tested techniques, which could minimize blasting damage and improve the over-all tunnel quality.

  • 5.
    Ittner, Henrik
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi. Swedish Nuclear Fuel and Waste Management Company (SKB).
    Åkeson, Urban
    Swedish Transport Administration (TRV).
    Christiansson, Rolf
    Swedish Nuclear Fuel and Waste Management Company (SKB).
    Olsson, Mats
    EDZ Consulting AB.
    Johansson, Daniel
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Recent Swedish Studies on the Extent of Blast Damage after Excavation2016Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper presents two recent studies on the extent of blast damage after excavation in crystalline rock. The Swedish Transport Administration and the Swedish Nuclear Fuel and Waste Management Company (SKB) are both under regulations to limit excavation damage during construction of tunnels. SKB is also required to limit the Excavation Damage Zone (EDZ), as this could be a potential flow path for radionuclides in the planned repository for spent nuclear fuel.Presented in this paper are investigations of blast damage from three tunnel sites, a road tunnel, an experimental tunnel in Äspö Hard Rock Laboratory and an underground subway depot.As expected the fractures resulting from the bottom charge are both longer and more frequent then those mapped in the column charge. The results show that the requirement to limit blast damage according to Swedish regulations was fulfilled for the column charge at the three studied sites.

  • 6.
    Ittner, Henrik
    et al.
    Swedish Nuclear Fuel and Waste Management Company (SKB).
    Bouvin, Anders
    Forcit Sweden AB.
    Investigation of blast damage from string emulsion in the wall and floor of two experimental tunnels in Äspö HRL2015Konferensbidrag (Refereegranskat)
    Abstract [en]

    A project was initiated by SKB and Forcit Sweden AB to investigate blast damage from emulsion explosives in two experimental tunnels in Äspö HRL. The new tunnels were excavated with emulsion explosives (Kemitti 810) and charging was done with a Forcit charging unit model 201. Extensive documentation of the excavation works was conducted, so that charge concentration per hole is traceable in contour, floor and helpers. Contour and floor holes were charged with concentration 0.35 and 0.5 kg/m respectively. In order to study blast fractures, five slots were excavated in the wall and floor. The results from mapping of the slots shows a longest blast fracture of 24.5 cm for the 0.35 kg/m charge and 24.1 cm for the 0.5 kg/m charged holes. Generally, there is a large spread in the results with few fractures longer than 20 cm.

  • 7.
    Ittner, Henrik
    et al.
    Swedish Nuclear Fuel and Waste Management Company (SKB).
    Bouvin, Anders
    Forcit Sweden AB.
    Undersökning av sprängsprickor från mekaniserad laddning med bulkemulsion i bergtunnel2015Rapport (Övrigt vetenskapligt)
    Abstract [sv]

    Det finns ett behov inom berg- och tunnelbranschen i Sverige av en praktiskt tillämpbar skadezonstabell för moderna emulsionssprängämnen. Behovet är tydligast när krav ställs på minimerad påverkan på kvarstående berg. Minimerad sprängskada i tunnlar kan reducera mängden överberg, oönskade bergutfall samt skrotningsbehov, både under bygg- och driftskede. Den här rapporten redovisar resultat från det första projektsteget i BeFo-projektet Underlag till skadezonstabell för emulsionssprängämne i bergtunnlar, som är ett sammarbetsprojekt mellan Svensk Kärnbränslehantering AB (SKB) och Forcit Sweden AB. Steg I omfattade sammanställning av befintlig laddningsdata mot sprängsprickor för två experimenttunnlar som byggdes i Äspölaboratoriet under 2012. Tunnlarna drevs med emulsionssprängämne (Kemitti 810) och dokumentation av bergarbetena under entreprenaden var omfattande. Mängden emulsionssprängämne per hål är därför spårbart i kontur, sula och hjälpare. I Steg II planerar projektet att komplettera och data från steg I med data från en annan site för att ta fram ett mer komplett underlag till en framtida skadezonstabell för emulsionssprängämne.För att studera sprängsprickor i vägg och sula har 5 slitsar sågats ut i två av de nya experimenttunnlarna på -410 m nivån i Äspölaboratoriet. Snitten lokaliserades genom kontroll av data från sprängning, GPR-reflektorer samt synliga borrpipor. Projektets ambition har varit att data skall ha hög tillförlitlighet och att hela processen skall vara väldokumenterad. Slitsarna karterades med avseende på både sprängsprickor och geologiska sprickor. Karteringsdata har sedan satts samman med laddningsdata från utbyggnadsprojektet. Kontur- och sulhål i de aktuella tunnlarna laddades med 0,35 respektive 0,5 kg/m. Resultatet från karteringen av sprängsprickor visar på en längsta radiell spricklängd om 24,5 cm för laddningskoncentrationen 0,35 kg/m och 24,1 cm för laddningskoncentrationen 0,5 kg/m. Generellt visar resultatet stor spridning med få sprickor längre än 20 cm.Resultatet är mycket bra för laddning med strängemulsion och den begränsade sprickbildningen tyder på en mycket bra borrnoggrannhet, en låg laddningskoncentration och att hålen detonerat momentant. Kontur- och sulhålen har initierats med elektroniska sprängkapslar och dessa har en mycket låg tändspridning vilket tidigare undersökningar visat ge kortast sprickbildning (Olsson och Ouchterlony, 2003).

  • 8.
    Ittner, Henrik
    et al.
    Swedish Nuclear Fuel and Waste Management Company (SKB).
    Lehtimäki, Tomas
    Swedish Nuclear Fuel and Waste Management Company (SKB).
    Christiansson, Rolf
    Swedish Nuclear Fuel and Waste Management Company (SKB).
    Design and control of the EDZ for a deep repository in crystalline rock2014Konferensbidrag (Refereegranskat)
    Abstract [en]

    Knowledge about the Excavation Damaged Zone (EDZ) is essential for underground construction design, underground facility layout, work environment issues and analysis of post-closure safety for a final repository for nuclear waste. The EDZ is defined as the zone around a tunnel where the damage is not reversible. The EDZ can be caused by the excavation method as well as by the actual strength–stress conditions.SKB has chosen the Forsmark site for disposal of spent fuel. The site conditions include hard crystalline rock and fairly high stresses. However, analyzes prior to site selection found that the risk for stress induced development of an EDZ is limited. The aim of this paper is to outline the blast design concept and quality control measures to ensure that the excavation method fulfills the requirements. Strategies for blast design and QA/QC measures for tunnel excavation were applied during construction works for the Äspö HRL expansion 2012. This provided an opportunity to demonstrate methods for tunnel excavation and verify that requirements on minimizing the EDZ could be met during the construction of the planned Swedish final repository for spent fuel.

  • 9.
    Ittner, Henrik
    et al.
    Swedish Nuclear Fuel and Waste Management Company (SKB).
    Bouvin, Anders
    Forcit Sweden AB.
    Fogdeby, Magnus
    Forcit Sweden AB.
    Kainulainen, Ari
    Forcit Sweden AB.
    Karlzén, Rickard
    Uppländska Bergborrnings AB.
    Kontursprängning i Äspö Utbyggnad -Dokumentation av strängladdning med emulsion i tunnelkontur2014Konferensbidrag (Refereegranskat)
    Abstract [sv]

    SAMMANFATTNING:SKBs krav på bergschakt, som tillämpades i utbyggnadsprojektet på Äspö, är relaterade till KBS-3 metoden för deponering av använt kärnbränsle. Metoden innebär deponering av använt kärnbränsle i kopparkapslar, 500 m under mark i ett system av deponeringstunnlar som sedan återfylls med bentonitlera.Under 2012 byggdes Äspölaboratoriet ut för att tillgodose behovet av utrymmen för experimentplatser. Nya tunnlar byggdes på -410 och -450 m nivån. Tunnlarna drevs med emulsionssprängämne (Kemitti 810) och laddning utfördes med en laddutrustning modell Forcit laddenhet 201 med slangdragare för strängladdade håltyper. Omfattande dokumentation av bergarbetena har gjorts under projektet så att mängden emulsionsprängämne per hål är spårbart i kontur, sula och hjälpare.För att studera spränginducerade sprickor i vägg och sula planeras ett antal sågsnitt i två av de nya experimenttunnlarna på -410 m nivån i Äspölaboratoriet. Ambitionen är att bidra till kunskap om sprängskadezon (EDZ) orsakad av emulsionssprängämne under realistiska förhållanden vid tunneldrivning. Försök planeras också med Forcits nyutvecklade laddenhet ECMII.

  • 10.
    Ittner, Henrik
    et al.
    Swedish Nuclear Fuel and Waste Management Company (SKB).
    Christiansson, Rolf
    Swedish Nuclear Fuel and Waste Management Company (SKB).
    Quality Control, Traceability and Verification of the Process for Construction of Deposition Tunnels2014Konferensbidrag (Refereegranskat)
    Abstract [en]

    The unique requirements on post-closure safety related to the construction of a disposal facility for spent nuclear fuel demands measures to control and verify the construction process. The Swedish Nuclear Fuel and Waste Management Company (SKB) have selected the Forsmark site for construction of a repository facility. Traceability in all work steps is necessary in order to verify that requirements for post-closure safety on the underground openings are met. This puts high demands on the construction of the deposition tunnels, as well as on the documentation of the construction works.The Äspö Hard Rock Laboratory (HRL), Sweden, is used by SKB for research and development of technology required for the final repository for spent nuclear fuel. During 2012 the HRL was expanded with 308 meters of new main and experimental tunnels. This was a good opportunity for SKB to apply requirements related to control, traceability and verification of the drill and blast excavation method. The tunnels were excavated using a factory new drilling jumbo and emulsion explosives, both with modern logger equipment, in order to receive a good control and documentation of drilling and charging works. The control plans for the work included additional measures to control, document and verify the process and results of the excavation. This paper aims to describe and exemplify the process of blast design, quality control, documentation and verification of the excavation works together.

  • 11.
    Ittner, Henrik
    et al.
    Swedish Nuclear Fuel and Waste Management Company (SKB).
    Olofsson, Isabelle
    Swedish Nuclear Fuel and Waste Management Company (SKB).
    Johansson, Emmeli
    Swedish Nuclear Fuel and Waste Management Company (SKB).
    Experiance from low-pH grouting at 400 m depth in the Äspö HRL expansion Project2013Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper presents experiences from the conducted grouting works regarding low-pH grout, grouting equipment, control and quality assurance which were acquired during the Äspö HRL expansion project. Companion papers describe the strategy for geoscientific investigations and modelling (Morosini and Hultgren, 2013) and the grouting strategy using the observational method (Olofsson et al., 2013a). Äspö HRL was expanded during 2012 in order to create new experimental sites as well as to develop and verify SKBs methods for tunnel construction. One of the objectives for the Äspö expansion project was to apply a full-scale industrialized test with low-pH grouting material. During complementary grouting in the fans intersecting water bearing fractures plastic plugs of grout were pushed out of the grouting boreholes due to hydraulic connections between holes and slow shear strength development in the low-pH grout. Grouting each fan in two steps and extended time for hardening during the excavation cycle proved to be the most efficient measures to handle the problems related to the slow hardening process of the low-pH grout.

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