Prediction of stress-driven rock mass damage in spent nuclear fuel repositories in hard crystalline rock and in deep underground mines

Lauri Uotinen

Prediction of stress-driven rock mass damage in spent nuclear fuel repositories in hard crystalline rock and in deep underground mines

Julkaisun otsikon käännös: Kallion jännitystilavaurioiden ennustaminen käytetyn ydinpolttoaineen loppusijoitustiloissa ja syvissä kaivoksissa

Lauri Uotinen

Rakennustekniikan laitos

Tutkimustuotos: Doctoral Thesis › Collection of Articles

Abstrakti

Ydinenergialaitoksia on ollut olemassa 1950-luvulta lähtien, ja ne tuottavat 11 % maailman sähköntarpeesta. Maailmanlaajuisesti 30 maata käyttää 448:aa ydinreaktoria sähköntuotantoon, ja 57 uutta reaktoria on rakenteilla 15 maassa. Mitattuna kuolemantapauksilla terawattituntia kohden ydinenergia on turvallisin tapa tuottaa energiaa, mutta se tuottaa myös erilaisia ydinjätteitä, joista täytyy huolehtia turvallisesti ja vastuullisesti. Syvä geologinen säilö on tällä hetkellä ainoa hyväksytty pitkäaikainen ratkaisu korkea-aktiiviselle ydinjätteelle. Kalliotilojen sortumat voivat tapahtua useista eri syistä, mutta kaksi yleisintä syytä ovat rakenteellinen painovoimainen murtuma ja jännityksen aiheuttama murtuma. Yleensä pinnassa ja lähellä pintaa tehtävissä louhinnoissa on kyse rakenteellisista painovoimaisista murtumista, mutta syvemmissä kalliotiloissa maankuoren jännitys ja jännitysvaurioiden todennäköisyys kasvavat. Viisi yleisintä jännitysvauriomekanismia ovat i) kallioräiske, ii) hilseily, iii) siirtymä, iv) leikkautuminen, v) seisminen. Liiallinen siirtymä on harvoin ongelma kovassa, massiivisessa kalliossa. Tässä väitöskirjassa käsitellään jäljelle jäävää neljää mekanismia. Tutkimuksen päätavoitteina on selvittää ohuiden ruiskubetonikuorien jännitysvaurioita vähentävän vaikutuksen suuruus, määrittää pitkien rakojen mekaaniset ominaisuudet ja kehittää reaaliaikainen riskienhallintakonsepti. Numeerista mallintamista käytettiin betonin hilseilyn in situ -kokeen (ICSE) suunnittelemiseksi. Laboratoriomittakaavan rakojen laastijäljenteitä käytettiin mittakaavavaikutuksen tutkimiseksi, ja ison mittakaavan 2,00 m kertaa 0,95 m (ASPERT) sekä 0,50 m kertaa 0,25 m rakonäytteet leikkauskuormitettiin menetelmien varmentamiseksi. Uutta reaaliaikaista geoteknistä riskienhallintakonseptia (GRM) tutkittiin esimerkkitapauksia sekä tapaustietoja käyttäen. Uusia menetelmiä kehitettiin kallion rakopintojen fotogrammetriseen tallentamiseen ja suurten rakonäytteiden leikkauskoestamiseen. Numeerisen mallinnuksen ennusteet ICSElle osoittavat, että ohut betonikuori tuottaa enintään 3 MPa tukipaineen, ja käyttämällä moniaksiaalista Ottosen murtokriteeriä betonikuori ei vaurioidu lämmitysvaiheen aikana. Sekä replikaleikkauskoesarjassa että isommissa leikkauskokeissa havaittiin negatiivinen mittakaavavaikutus. Esimerkkiaineiston alustavien analyysien perusteella Bayes-verkot vaikuttavat yhteensopivilta seurantamenetelmän kanssa, ja lähestymistapa on valmis testattavaksi todellisella datalla. Kaikki kolme pääjohtopäätöstä liittyvät jännitysvaurioitumiseen sekä sen vähentämiseen. Jännitysvaurioita voidaan vähentää ohuiden betonikuorien tukipaineen avulla. Uusi menetelmä kehitettiin kalliorakojen geometrian digitoimiseksi ja laastijäljenteiden valmistamiseksi laboratoriomittakaavan rasialeikkauskokeita varten. Bayes-verkkojen käyttöä havainnollistettiin yhdessä reaaliaikaisen geoteknisen riskienhallintakonseptin kanssa.

Julkaisun otsikon käännös	Kallion jännitystilavaurioiden ennustaminen käytetyn ydinpolttoaineen loppusijoitustiloissa ja syvissä kaivoksissa
Alkuperäiskieli	Englanti
Pätevyys	Tohtorintutkinto
Myöntävä instituutio	Aalto-yliopisto
Valvoja/neuvonantaja	Rinne, Mikael, Vastuuprofessori Rinne, Mikael, Ohjaaja
Kustantaja	Aalto University
Painoksen ISBN	978-952-60-8004-8
Sähköinen ISBN	978-952-60-8005-5
Tila	Julkaistu - 2018
OKM-julkaisutyyppi	G5 Tohtorinväitöskirja (artikkeli)

Tutkimusalat

hilseily
kallioräiske
fotogrammetria
leikkauskoe
riskienhallinta

Pääsy asiakirjaan

http://urn.fi/URN:ISBN:978-952-60-8005-5Lisenssi: CC BY

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@phdthesis{686bfc393ca646d28e110d414013155d,

title = "Prediction of stress-driven rock mass damage in spent nuclear fuel repositories in hard crystalline rock and in deep underground mines",

abstract = "Nuclear plants have existed since the 1950s, and they provide 11 % of the world's electricity production. Worldwide, 30 countries are operating 448 nuclear reactors for electricity generation, and 57 new nuclear plants are under construction in 15 countries. Measured by deaths per terawatt hour, nuclear power is the safest method to provide energy, but it does produce a range of radioactive waste, which must be disposed of safely and responsibly. The deep geological repository is currently the only acceptable long-term solution for high-level nuclear waste. The two most common causes of rock mass failure are structurally controlled gravity-driven failure and stress-induced failure. Usually, surface and near-surface rock excavations are subject to structurally controlled gravity-driven problems, but in deep rock spaces, the in-situ stress of the rock mass increases and the risk of stress-driven problems grows. The five most common stress-driven damage mechanisms are i) rockburst, ii) spalling, iii) convergence, iv) shearing and v) seismic. Excessive convergence is rarely a problem in hard, massive rock mass. In this thesis, the remaining four mechanisms are addressed. The goals of the research were to discover the damage-reducing capability of thin sprayed concrete liners, to define the strength of long rock joints, and to develop a real-time risk management concept. Numerical modelling was used to design an in-situ concrete spalling experiment, the ICSE. Laboratory scale mortar rock joint replicas were used to study the scale effect, and large 2.00 m by 0.95 m (ASPERT) and 0.50 m by 0.25 m rock joints were sheared to validate the methods. A new real-time formulation of the Geotechnical Risk Management (GRM) concept was studied using both example cases and case data. New methods were developed for the photogrammetric capture of rock joint surfaces and shear testing of large rock samples. The numerical modelling predictions for the in-situ experiment show that the thin concrete liner produces up to 3 MPa of support pressure and using polyaxial Ottosen criterion the liner is not damaged during the heating stage. Both the replica shear tests and the large shear tests results show a weak negative scale effect. Based on the initial analyses using example data, Bayesian networks appear compatible with the Observational Method, and the approach is ready to be tested using real data. The three main conclusions each address the stress-driven damage prediction and mitigation. The stress-driven damage can be reduced using support pressure generated by thin concrete liners. A new method was developed to capture rock joint geometry using photogrammetry and to manufacture mortar replicas for laboratory scale shear testing. The use of Bayesian networks, together with the real-time geotechnical risk management concept, was demonstrated. The results contribute towards predicting stress-driven damage in deep underground spaces.",

keywords = "spalling, rockburst, photogrammetry, shear test, risk management, hilseily, kallior{\"a}iske, fotogrammetria, leikkauskoe, riskienhallinta, spalling, rockburst, photogrammetry, shear test, risk management",

author = "Lauri Uotinen",

year = "2018",

language = "English",

isbn = "978-952-60-8004-8",

series = "Aalto University publication series DOCTORAL DISSERTATIONS",

publisher = "Aalto University",

number = "98",

address = "Finland",

school = "Aalto University",

}

TY - THES

T1 - Prediction of stress-driven rock mass damage in spent nuclear fuel repositories in hard crystalline rock and in deep underground mines

AU - Uotinen, Lauri

PY - 2018

Y1 - 2018

N2 - Nuclear plants have existed since the 1950s, and they provide 11 % of the world's electricity production. Worldwide, 30 countries are operating 448 nuclear reactors for electricity generation, and 57 new nuclear plants are under construction in 15 countries. Measured by deaths per terawatt hour, nuclear power is the safest method to provide energy, but it does produce a range of radioactive waste, which must be disposed of safely and responsibly. The deep geological repository is currently the only acceptable long-term solution for high-level nuclear waste. The two most common causes of rock mass failure are structurally controlled gravity-driven failure and stress-induced failure. Usually, surface and near-surface rock excavations are subject to structurally controlled gravity-driven problems, but in deep rock spaces, the in-situ stress of the rock mass increases and the risk of stress-driven problems grows. The five most common stress-driven damage mechanisms are i) rockburst, ii) spalling, iii) convergence, iv) shearing and v) seismic. Excessive convergence is rarely a problem in hard, massive rock mass. In this thesis, the remaining four mechanisms are addressed. The goals of the research were to discover the damage-reducing capability of thin sprayed concrete liners, to define the strength of long rock joints, and to develop a real-time risk management concept. Numerical modelling was used to design an in-situ concrete spalling experiment, the ICSE. Laboratory scale mortar rock joint replicas were used to study the scale effect, and large 2.00 m by 0.95 m (ASPERT) and 0.50 m by 0.25 m rock joints were sheared to validate the methods. A new real-time formulation of the Geotechnical Risk Management (GRM) concept was studied using both example cases and case data. New methods were developed for the photogrammetric capture of rock joint surfaces and shear testing of large rock samples. The numerical modelling predictions for the in-situ experiment show that the thin concrete liner produces up to 3 MPa of support pressure and using polyaxial Ottosen criterion the liner is not damaged during the heating stage. Both the replica shear tests and the large shear tests results show a weak negative scale effect. Based on the initial analyses using example data, Bayesian networks appear compatible with the Observational Method, and the approach is ready to be tested using real data. The three main conclusions each address the stress-driven damage prediction and mitigation. The stress-driven damage can be reduced using support pressure generated by thin concrete liners. A new method was developed to capture rock joint geometry using photogrammetry and to manufacture mortar replicas for laboratory scale shear testing. The use of Bayesian networks, together with the real-time geotechnical risk management concept, was demonstrated. The results contribute towards predicting stress-driven damage in deep underground spaces.

AB - Nuclear plants have existed since the 1950s, and they provide 11 % of the world's electricity production. Worldwide, 30 countries are operating 448 nuclear reactors for electricity generation, and 57 new nuclear plants are under construction in 15 countries. Measured by deaths per terawatt hour, nuclear power is the safest method to provide energy, but it does produce a range of radioactive waste, which must be disposed of safely and responsibly. The deep geological repository is currently the only acceptable long-term solution for high-level nuclear waste. The two most common causes of rock mass failure are structurally controlled gravity-driven failure and stress-induced failure. Usually, surface and near-surface rock excavations are subject to structurally controlled gravity-driven problems, but in deep rock spaces, the in-situ stress of the rock mass increases and the risk of stress-driven problems grows. The five most common stress-driven damage mechanisms are i) rockburst, ii) spalling, iii) convergence, iv) shearing and v) seismic. Excessive convergence is rarely a problem in hard, massive rock mass. In this thesis, the remaining four mechanisms are addressed. The goals of the research were to discover the damage-reducing capability of thin sprayed concrete liners, to define the strength of long rock joints, and to develop a real-time risk management concept. Numerical modelling was used to design an in-situ concrete spalling experiment, the ICSE. Laboratory scale mortar rock joint replicas were used to study the scale effect, and large 2.00 m by 0.95 m (ASPERT) and 0.50 m by 0.25 m rock joints were sheared to validate the methods. A new real-time formulation of the Geotechnical Risk Management (GRM) concept was studied using both example cases and case data. New methods were developed for the photogrammetric capture of rock joint surfaces and shear testing of large rock samples. The numerical modelling predictions for the in-situ experiment show that the thin concrete liner produces up to 3 MPa of support pressure and using polyaxial Ottosen criterion the liner is not damaged during the heating stage. Both the replica shear tests and the large shear tests results show a weak negative scale effect. Based on the initial analyses using example data, Bayesian networks appear compatible with the Observational Method, and the approach is ready to be tested using real data. The three main conclusions each address the stress-driven damage prediction and mitigation. The stress-driven damage can be reduced using support pressure generated by thin concrete liners. A new method was developed to capture rock joint geometry using photogrammetry and to manufacture mortar replicas for laboratory scale shear testing. The use of Bayesian networks, together with the real-time geotechnical risk management concept, was demonstrated. The results contribute towards predicting stress-driven damage in deep underground spaces.

KW - spalling

KW - rockburst

KW - photogrammetry

KW - shear test

KW - risk management

KW - hilseily

KW - kallioräiske

KW - fotogrammetria

KW - leikkauskoe

KW - riskienhallinta

KW - spalling

KW - rockburst

KW - photogrammetry

KW - shear test

KW - risk management

M3 - Doctoral Thesis

SN - 978-952-60-8004-8

T3 - Aalto University publication series DOCTORAL DISSERTATIONS

PB - Aalto University

ER -

Prediction of stress-driven rock mass damage in spent nuclear fuel repositories in hard crystalline rock and in deep underground mines

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