| 1. |
- Bjureland, William, et al.
(författare)
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Some aspect of reliability-based design for tunnels using observational method (EC7)
- 2015
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Ingår i: EUROCK 2015 & 64th Geomechanics Colloquium. - Salzburg.
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Konferensbidrag (refereegranskat)abstract
- According to Eurocode 7, the observational method is an accepted design method, where a preliminary design may be updated as the construction progresses. However, Eurocode 7 does not give any advice on how to relate the observations to the acceptable level of safety of the structure. In this paper, we outline a methodology for how to use deformation measurements to predict the final deformation of a circular rock tunnel to calculate the probability of failure. Consequently, the measurements can be used to verify that the design does not violate the specified safety level. The paper shows the potential of combining the observational method with reliability-based design in tunneling
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| 2. |
- El Tani, Mohamed, et al.
(författare)
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Grout Spread and Injection Period of Silica Solution and Cement Mix in Rock Fractures
- 2017
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Ingår i: Rock Mechanics and Rock Engineering. - : Springer. - 0723-2632 .- 1434-453X. ; 50:9, s. 2365-2380
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Tidskriftsartikel (refereegranskat)abstract
- A systematic presentation of the analytic relations of grout spread to the time period is established. They are divided following the nature of the flow, the property of the mix and the driving process. This includes channel flow between parallel plates and radial flow between parallel discs, nonlinear Newtonian fluids like silica solution, polyurethane and epoxy, and Bingham material like cement-based grout, and three grouting processes at a constant flow rate, constant pressure and constant energy. The analytic relations for the constant energy process are new and complete the relations of the constant flow rate and constant pressure processes. The well-known statement that refusal cannot be obtained during finite time for any injected material at a constant flow rate or constant injection pressure is extended to include the energy process. The term refusal pressure or energy cannot be supported for stop criteria. Stop criteria have to be defined considering confirmed relation of the spread to the time period and of the flow rate to the pressure and spread. It is shown that it is always possible to select a grouting process along which the work will exceed any predefined energy, the consequence of which is that jacking is related to the applied forces and not to the injected energy. Furthermore, a clarification is undertaken concerning the radial flow rate of a Bingham material since there are two different formulations. Their difference is explained and quantified. Finally, it is shown that the applied Lugeon theory is not supported by the analytic relations and needs to be substantially modified.
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| 3. |
- Harrison, J. P., et al.
(författare)
-
Rock engineering design and the evolution of Eurocode 7 : The critical six years to 2020
- 2017
-
Ingår i: 13th ISRM International Congress of Rock Mechanics. - : International Society for Rock Mechanics. - 9781926872254
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Konferensbidrag (refereegranskat)abstract
- In 2010, the Eurocode for Geotechnical Design, EN-1997-1:2004 (CEN, 2004), informally known as Eurocode 7 or EC7, became the Reference Design Code (RDC) for geotechnical design - including rock engineering design - within the European Union (EU). EC7 is one standard within the comprehensive Structural Eurocode suite, which as a whole has been also adopted by a number of other countries beyond the EU. EC7 is thus becoming a key design standard for geotechnical engineering worldwide. As part of the Structural Eurocode suite, EC7 requires designs to adhere to the principles of Limit State Design. However, it is not clear that current rock engineering design practice can satisfy this requirement. In addition, evidence is accumulating that EC7 is currently difficult to apply to, and may even be inappropriate for, rock engineering design. These issues may be due to the fact that the development of EC7 to date took place without any formal input from the international rock mechanics and rock engineering community. In early 2011 under the auspices of CEN (Comité Européen de Normalisation / European Committee for Standardisation), EC7 entered a formal period of maintenance which was aimed at improving the applicability and ease-of-use of the Code. This maintenance cycle will conclude in 2020 with the publication of a revised version of EC7. This paper describes a number of critical aspects for rock engineering in the context of EC7, in particular the following: - the history of the Structural Eurocodes and the concepts they embody; - the nature of Limit State Design and the challenges and opportunities it poses for rock engineering design; - the formal means by which the Structural Eurocode maintenance cycle proceeds; - the plans currently being developed for improving EC7 with regard to rock engineering design and construction; - the unique and vital opportunity for the entire international rock mechanics and rock engineering community to comment on the Code and make suggestions for its improvement.
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| 4. |
- Johansson, Fredrik, 1973-, et al.
(författare)
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Investigation of research needs regarding the storage of hydrogen gas in lined rock caverns : Prestudy for Work Package 2.3 in HYBRIT Research Program 1
- 2018
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The objective of HYBRIT RP1 is to explore and assess pathways to fossil-free energy-mining-iron-steel value chains and thereby provide a basis for industrial development activities and the necessary future transformative change in this field. A large-scale storage capacity for hydrogen gas is an important component of the proposed HYBRIT concept. Underground storage in lined rock caverns provides a reasonable option: a large-scale demonstration plant for storage of natural gas was constructed in Sweden in 2002 and has operated safely since then. Considering that this lined rock cavern facility was constructed for natural gas, the present report investigates the current research needs to allow for underground storage of hydrogen gas in such a facility. This will serve as a basis for the research in Work Package 2.3 of HYBRIT RP1.Studying the experiences from decades of Swedish and international research and practice on the construction of underground gas storage facilities, the conclusion is that the lined rock cavern concept seems a reasonable way forward. In terms of rock engineering research, there are currently no critical research issues; however, a development of a previously proposed risk-based design framework for lined rock caverns may further strengthen the ability to manage risks related to underground gas storage facilities. The report identifies several potential research questions on this topic to be further studied: development of a risk-based design approach using subset simulation, the optimization potential of the concrete thickness in the lining, and the effect of spatial variation of rock mass properties on a location’s suitability for the storage facility.Additionally, the report identifies the potential effect of hydrogen embrittlement on the steel lining as a critical research issue to ensure safe storage of hydrogen gas in lined rock caverns. However, as this issue is not related to rock engineering, but a material issue, it will not be covered further in Work Package 2.3.
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| 5. |
- Olsson, Lars, et al.
(författare)
-
Framtidens riskhantering – nu med systemförståelse
- 2019
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Konferensbidrag (populärvet., debatt m.m.)abstract
- Geoteknikern hanterar i sin vardag många och ofta stora risker. Men trots att kostnaden för negativa utfall av geotekniska risker årligen bedöms ligga på flera miljarder kronor, används tillgängliga verktyg för strukturerad riskhantering sparsamt. I ett SBUF-projekt har vi tagit fram en vägledning för hur sådana verktyg kan användas i praktiken. Vi har i denna vägledning särskilt fokuserat på den för riskhanteringen så viktiga systemförståelsen av det geotekniska sammanhanget som man verkar i. Denna artikel är en sammanfattande kortversion av den slutrapport som författarna skrivit inom ramen för SBUF-projektet.
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| 6. |
- Rafi, Jalaleddin Yaghoobi, et al.
(författare)
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Basic mechanism of elastic jacking and impact of fracture aperture change on grout spread, transmissivity and penetrability
- 2015
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Ingår i: Tunnelling and Underground Space Technology. - : Elsevier BV. - 0886-7798 .- 1878-4364. ; 49, s. 174-187
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Tidskriftsartikel (refereegranskat)abstract
- One of the most important parameters in the grouting of rock fractures is the applied pressure. This produces the driving force on the Bingham group material that causes it to penetrate the fracture. However, deciding the optimum pumping pressure is challenging. Using too high a pressure not only causes the grout to spread beyond the desired area, but, if it exceeds the minimum in situ stress in the rock mass, may also cause jacking of the fractures. This may lead to uncontrolled uplift. With a lower grout pressure, this "ultimate state" (jacking) can be avoided, although the pressurized grout still may induce smaller elastic deformations during pumping, and these may become irreversible when the grout has hardened. In previous studies, various theoretical approaches to distinguish the onset of these elastic and non-elastic deformations have been described and evaluated. However, the merits and disadvantages of theoretical approaches in general have been questionable. In the current study, the basic mechanism of elastic jacking is described, and its negative consequences are analyzed and quantified. These are the prolongation of grouting time, and the reduction in sealing efficiency. The role of an increased grouting pressure is evaluated by considering its positive effect in improving the penetrability and comparing this with the potential negative consequences. Case studies from two projects (the THX and Citybanan projects) are studied to examine the efficiency of the work that was carried out on site. The results indicate a high-applied pressure can have negative effect on the grouting procedure, and that this effect is significant in fractures situated in weak rock at shallow depth. It is concluded that unwanted fracture deformations and their negative consequences can be eliminated by defining appropriate stop criteria in advance of grouting, and confirming their suitability during pumping by the use of theoretical approach presented here. In general, this will allow the use of lower pump pressure and allow better control of the grout spread.
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| 7. |
- Spross, Johan, 1986-, et al.
(författare)
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Geotekniska risker kan hanteras bättre
- 2016
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Ingår i: Bygg och Teknik. - Stockholm : Förlags AB Bygg och teknik. - 0281-658X .- 2002-8350. ; 108:1, s. 63-66
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Tidskriftsartikel (populärvet., debatt m.m.)
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| 8. |
- Spross, Johan, 1986-, et al.
(författare)
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Hantering av geotekniska risker i byggprojekt : Ett praktiskt tillämpningsexempel
- 2015
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Skador till följd av utfall av negativa geotekniska risker kostar stora summor för svensk byggindustri. Det krävs därför en effektiv och transparent riskhantering som kan minska kostnaderna. I dagsläget används sällan de verktyg som finns tillgängliga för riskhantering fullt ut i byggprojekten.Denna rapport visar hur ett sådant verktyg, Svenska Geotekniska Föreningens metodbeskrivning för geoteknisk riskhantering (SGF Rapport 1:2014), kan användas i praktiken. Vi ger ett omfattande illustrativt exempel på hur riskhantering kan utföras i alla skeden av ett typiskt geotekniskt projekt från idéfas till driftskede. Exemplet är fingerat men baserar sig på schakt och grundläggning till utbyggnaden av Hästsportens hus vid Solvalla travbana från 1992.Det är vår uppfattning att metodiken i SGF Rapport 1:2014 är tillämpbar på alla skeden i byggprocessen, från idéfas till driftfas, i både stora och små projekt. Det är dock avgörande att riskhanteringen anpassas till varje nytt projekt eller projektskede. Det strukturerade arbetssättet som metodiken ger höjer kvalitén på riskhanteringen jämfört med ett ad hoc-betonat arbetssätt, som man ofta ser i dagens projektstyrning.Med tanke på denna höjda kvalitet menar vi att riskkostnaderna kan bli mindre. En absolut grund för detta är dock att man uppfyller de fyra baskraven. Dessa syftar dels till att skapa och upprätthålla en kultur där man är medveten om risker som finns hur de påverkar projektet, dels till att definiera och tydliggöra riskhanteringen inom organisationen så att inget faller mellan stolarna. Därför är det viktigaste kravet att den som bestämmer har en medveten risksyn.
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| 9. |
- Spross, Johan, 1986-, et al.
(författare)
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Hur ska bergbyggande kunna inkluderas i Eurokod 7 : How to include rock engineering in Eurocode 7
- 2019
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Ingår i: Proceedings Bergdagarna 2019.
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Konferensbidrag (populärvet., debatt m.m.)abstract
- I dagsläget har många länder, däribland Sverige, valt att inte tillämpa Eurokod 7 vid byggande i berg. Eurokod 7 är dock för närvarande under omarbetning, bland annat med syftet att bättre inkludera bergbyggande i dess tillämpningsområde. En sådan omarbetning kräver dock att koden anpassas till bergbyggandets egenheter, eftersom byggande i berg fundamentalt skiljer sig från byggande av de flesta andra typerna av konstruktioner. I denna presentation framför vi vår syn på hur en designkod för bergkonstruktioner behöver vara uppbyggd för att säkerställa att nya konstruktioner både blir tillräckligt säkra och kan byggas på ett kostnadseffektivt sätt. En viktig utgångspunkt är den beslutsteoretiska kopplingen mellan dimensionering och riskhantering som alltid bör genomsyra byggande i jord och berg. Presentationen bygger på resultatet av BeFo-projekt 395, som avslutades i januari 2019.
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| 10. |
- Spross, Johan, 1986-, et al.
(författare)
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On the Need for a Risk-Based Framework in Eurocode 7 to Facilitate Design of Underground Openings in Rock
- 2018
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Ingår i: Rock Mechanics and Rock Engineering. - : Springer. - 0723-2632 .- 1434-453X. ; 51:8, s. 2427-2431
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Tidskriftsartikel (refereegranskat)abstract
- The European design code for geotechnical engineering, EN-1997 Eurocode 7, is currently under revision. As design of underground openings in rock fundamentally differs from design of most other types of structures, the revised Eurocode 7 must be carefully formulated to be applicable to underground openings. This paper presents the authors' view of how a design code for underground openings in rock needs to be organized to ensure that new structures are both sufficiently safe and constructed cost-effectively. The authors find that the revised version of Eurocode 7 carefully must acknowledge the fundamental decision-theoretical connection between design and risk management that should permeate all geotechnical design work. Otherwise, if the revised code is not given a risk-based framework, the authors fear that, as a consequence, the observational method will not be favorable to use in excavations of underground openings in rock. Then, cost-effective construction will be very difficult to achieve.
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| 11. |
- Spross, Johan, 1986-, et al.
(författare)
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The Swedish Geotechnical Society's methodology for risk management : a tool for engineers in their everyday work
- 2018
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Ingår i: Georisk. - : TAYLOR & FRANCIS LTD. - 1749-9518 .- 1749-9526. ; 12:3, s. 183-189
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Tidskriftsartikel (refereegranskat)abstract
- The Swedish Geotechnical Society has adopted a general methodology for risk management in geotechnical engineering projects to reduce the costs related to negative outcomes of geotechnical risks. This technical note highlights the main features of the methodology and strives to inspire the international geotechnical community to apply sensible risk management methods. In the authors' opinion, a successful geotechnical risk management needs to be structured, be tailored to the project, and permeate the engineers' everyday work. Then, sufficient quality can be achieved in the project with larger probability.
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| 12. |
- Spross, Johan, 1986-, et al.
(författare)
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Utredning av riskbaserade principer inom bergdimensionering : Så bör en standard vara uppbyggd
- 2019
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Utformningen av bergkonstruktioner behöver normalt uppfylla en mängd olika krav. Dessakrav kan komma såväl från beställare, som genom lagkrav, miljödomar och byggnormer. Bergmekanikern som utför dimensioneringen har att ta hänsyn till alla dessa krav och skasamtidigt så långt som möjligt optimera konstruktionen så att beställaren får största möjliganytta för pengarna. I Sverige gäller sedan 2010 de EU-gemensamma byggreglerna Eurokodernainom i stort sett all byggkonstruktion – dock inte inom bergbyggnad. I denpågående revideringen av Eurokod 7 är dock ett syfte att förbättra tillämpbarheten inombergbyggande. Det har dock saknats en vetenskaplig grund att stå på avseende just revideringenav reglerna för bergbyggande. Syftet med forskningsprojektet, som avslutas i ochmed denna slutrapport, har därför varit att vetenskapligt stödja de som arbetar medEurokodrevideringen genom att publicera två vetenskapliga artiklar på området.Forskningsprojektet har främst fokuserat på de övergripande dimensioneringsprincipernaoch hur dessa behöver ses ur ett riskhanteringsperspektiv. Som vi ser det, är det väsentligtatt den reviderade Eurokod 7 är uppbyggd enligt riskbaserade principer. Det innebär attdimensionering behöver ses som en del av det nödvändiga strukturerade riskhanteringsarbetesom ska utföras i byggprojekt. I de två bifogade artiklarna visar vi hur dimensioneringkan tolkas i enlighet med de generella riskhanteringsprinciper som finns i standardenISO 31000. Med en sådan tolkning kan dimensioneringen utföras på ett transparent ochstrukturerat sätt. Därmed kan dimensioneringsarbetet även integreras i det allmänna hanteradeav risker som utförs i byggprojekt.I Artikel I diskuterar vi översiktligt de övergripande principerna för hur en designkod förbergbyggande behöver vara organiserad för att ge samhället ett kostnads- och resurseffektivtbergbyggande, som samtidigt ger tillräckligt säkra konstruktioner. Vi diskuterarsärskilt betydelsen av att observationsmetoden integreras på ett jämbördigt sätt i designkodentillsammans med övriga tillåtna verifieringsmetoder för gränstillstånd.I Artikel II tar vi ett helhetsgrepp om frågan vad riskbaserad dimensionering egentligeninnebär. Artikeln presenterar ett generellt ramverk för dimensionering av bergkonstruktioner, där en grundförutsättning har varit att dimensionering måste ses som beslutsfattandeunder osäkra förhållanden. Vi diskuterar och strukturerar de beslut och övervägandensom behöver göras i dimensioneringsarbetet och visar hur besluten kan fattas urett riskperspektiv. För att stödja arbetet med revideringen av Eurokod 7 diskuterar vi ocksåpå vilket sätt som det presenterade ramverket kan implementeras i en designkod. En viktiggrundprincip är att koden utformas så att bergmekanikern ges möjlighet att anpassa hanteringenav de risker, som identifieras under dimensioneringsarbetet, till de aktuella förhållandenai projektet. Kodförfattarna bör alltså avstå från att ange alltför detaljerade kravavseende exempelvis utformning av förundersökningar. I annat fall kan effekten bli attpotentiellt dyra åtgärder behöver utföras inte för att de behövs ur ett riskperspektiv, utanendast för att koden kräver det. Det skulle enligt vår åsikt rimma illa med det övergripandemålet om en långsiktigt hållbar samhällsutveckling.
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| 13. |
- Spross, Johan, 1986-, et al.
(författare)
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Would risk management have helped? – A case study
- 2015
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Ingår i: Geotechnical safety and risk V. - Amsterdam : IOS Press. - 9781614995807 - 9781614995791
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Konferensbidrag (refereegranskat)abstract
- To reduce the costs of unexpected geotechnical events in construction projects in Sweden, the Swedish Geotechnical Society has adopted a general methodology for risk management. In this paper, we exemplify how the proposed risk management philosophy could have been applied on a sheet-pile wall, which failed in 1992 in Stockholm because the design did not consider the complex site conditions. Focusing on the design phase, we discuss how geotechnical risks may be managed effectively as a natural part of the engineer’s everyday work.
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| 14. |
- Stille, Håkan
(författare)
-
Geological Uncertainties in Tunnelling - Risk Assessment and Quality Assurance
- 2017
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Ingår i: Sir Muir Wood Lecture 2017. - : The International Tunnelling and Underground Space Association. - 9782970112211
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Konferensbidrag (refereegranskat)abstract
- Risk is always present in rock tunnelling. The uncertainties connected to design and execution, especially geological uncertainties, are larger and to some degree different from those in other types of civil engineering projects. This implies that systems for handing the uncertainties like ISO 31 000 “Risk management –Principles and guidelines” must be adapted to the special conditions prevailing in underground projects. Risk management is, consequently, closely connected to project management. The work can be carried out in different ways in relation to the complexity of the project. However, site organizations with teams responsible for the geotechnical and geological follow-up is an important part of risk management in tunnelling. The project manager must have the overall responsibility.The uncertainties have to be treated as an integrated part with a set of activities within the project work and the ordinary project organization. Project models like Props, developed by Ericsson Infocom based on tollgates and milestones, are also very adequate.The base for risk evaluation should be the epistemic nature of geological uncertainties. Updating by observation and investigation can reduce the uncertainties. Systematic approaches for collecting additional information should be implemented. Lead-time to make adequate decisions may be obtained by identifying and looking for warning bells. In many situations such an approach will prevent unwanted events, like tunnel collapse, high water ingress and similar problems from happening.Rock design is affected by geological uncertainties. Models and material properties of the rock mass will have a much higher degree of uncertainty than other building material like concrete and steel. This implies that verification of the design cannot only be built on calculations as normal in civil engineering. The observational approach in tunnelling will therefore in most cases be mandatory and can be regarded as part of the risk assessment and quality control. A common approach in tunnel design is the adoption of prescriptive measures. Application of rock classification systems belongs to this category. The limitations of such approach need to be understood in order to achieve an adequate risk treatment.The overall quality is governed by two factors “doing the right things” and “doing the things right”. The special focus on the first issue comes from the special uncertainties connected to underground works. The system is called “Dual quality system”. Geotechnical category as defined in the new Euro Code (EC7) is an essential part in applying a dual quality system but it has to be adapted to rock engineering problems.The above described approach for risk assessments and quality assurance in rock engineering and tunnelling is based on experiences from tunnel projects and supported by theories of uncertainties.
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| 15. |
- Stille, Håkan, et al.
(författare)
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Practical use of the concept of geotechnical categories in rock engineering
- 2018
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Ingår i: Tunnelling and Underground Space Technology. - : Elsevier. - 0886-7798 .- 1878-4364. ; 79, s. 1-11
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Tidskriftsartikel (refereegranskat)abstract
- The aim of the paper is to show how Eurocode 7: Geotechnical Design Part 1: General Rules (EC7) could be developed in order to be in accordance with practise in rock engineering and construction. A main feature is the geological uncertianties, which imply that a risk based approch should be used. The use of Geotechnical Category (GC) has therefore to be improved by (1) combining the consequences of a failure to the geological uncertainties before excavation, and (2) combining the consequences to the ground quality found after excavation. Three GC classes are needed to properly use the GC in rock construction. The paper further describes how GC influences the design, which design method to be applied. It also outlines the types of control, inspection and supervision to be applied in the various GC classes during various stages of a project. An example is presented showing how GC can be determined at various stages of a rock construction.
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| 16. |
- Yaghoobi Rafi, Jalaleddin, et al.
(författare)
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Applicability of using GIN method, by considering theoretical approach of grouting design
- 2015
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Ingår i: Geotechnical and Geological Engineering. - : Springer. - 0960-3182 .- 1573-1529. ; 33:6, s. 1431-1448
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Tidskriftsartikel (refereegranskat)abstract
- In the practice of grouting of fractured rock, currently, empirical methods are used. Amongst them, the GIN method is popular mostly in Europe and has been tried in many projects. The concept of this method is to limit the combination of pressure and injected volume to a specific grout intensity number in order to control the energy induced in the rock fractures and to avoid uplift. However, difficulties in employing this method have been reported, which are mainly due to uncertainties in recognizing the distance of grout penetration and the state of the fractures during grouting and at the completion grouting. In this paper, the purpose has been examining the applicability of the GIN method by defining the characteristic curve of the P·V diagram (referred to here as the hyperbola) and suggesting appropriate completion criteria based on the radius of grout spread around the borehole. This will provide the chance to assign a permitted level of fracture deformation (or jacking) to the GIN by considering the formulation of fracture deformation based on grout propagation in a previously developed theoretical approach by Stille et al. (Geotech Geol Eng 30:603–624, 2012) as a part of the Real Time Grouting Control Method. Thus, in attaining the hyperbola, the identified radius of grout spread is achieved and the resulting fracture deformation at this completion point can be beneficial in improving penetrability. However, if the full extent of this deformation extends beyond the grouted zone, part of the fracture may remain un-grouted, and this will affect the sealing efficiency of the grouting program. This may be continued by selecting a smaller GIN and reducing the grouting pressure as the real time pressure–volume plot moves along the hyperbola, which will bring the fracture back to its initial state as grouting approaches the completion point, i.e. when the grout has spread to the desired distance. This hypothesis has been examined against the grouting works performed in three different real projects, for which the grouting parameters can be determined from the available grouting records. It is concluded that the GIN used in practice was much higher than the theoretically estimated values obtained through the proposed analytical solution. Furthermore, in the grouting of fractures close to the surface, the radius of grout spread impacts the GIN significantly, and only a limited grouting pressure is applicable, thus in using split spacing technique in such circumstances, different GINs should be selected for different sets of boreholes to obtain enough propagation at the maximum applicable pressure. The introduced analytical solution introduced in this paper can be a useful procedure for designing the GIN based on the grout spread. Nevertheless, it becomes complicated in dealing with fracture deformation. In a difficult grouting case where the demand for sealing is high, the recommendation is to use the proposed theoretical approach, which provides detailed information during the actual grouting procedure, by estimation of the radius of grout spread and the state of the fracture in real time
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