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Geological Data Acquisition for Site Characterisation at Olkiluoto: a Framework for the Phase of Underground Investigations

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Geological Data Acquisition for Site Characterisation at Olkiluoto: a Framework for the Phase of Underground Investigations Working Report 2007-32 Geological Data Acquisition for Site Characterisation at Olkiluoto: a Framework for the Phase of Underground Investigations Alan Geoffrey Milnes Ismo Aaltonen, Kimmo Kemppainen, Jussi Mattila, Liisa Wikström Kai Front Aulis Kärki, Seppo Gehör Seppo Paulamäki, Markku Paananen Turo Ahokas May 2007 POSIVA OY FI-27160 OLKILUOTO, FINLAND Tel +358-2-8372 31 Fax +358-2-8372 3709 Working Report 2007-32 Geological Data Acquisition for Site Characterisation at Olkiluoto: a Framework for the Phase of Underground Investigations Alan Geoffrey Milnes GEA Consulting Ismo Aaltonen, Kimmo Kemppainen, Jussi Mattila, Liisa Wikström Posiva Oy Kai Front Technical Research Centre of Finland Aulis Kärki, Seppo Gehör Kivitieto Oy Seppo Paulamäki, Markku Paananen Geological Survey of Finland Turo Ahokas Pöyry Environment Oy May 2007 Base maps: ©National Land Survey, permission 41/MYY/07 Working Reports contain information on work in progress or pending completion. ABSTRACT “Geological data acquisition” is a general term for the collection of observations and measurements by direct observation of exposed bedrock in the field (i.e. in natural outcrops and trenches, in drillholes, and in tunnels and other underground excavations). Only field-based data acquisition is included in this report: laboratory-based investigations will be continued, based on the field data and sampling, and all the data will be subject to discipline-specific processing, as the project proceeds. The ultimate aim of geological data acquisition is to provide the necessary data base for geological models of the bedrock of the Olkiluoto site, in connection with the construction of an underground rock characterisation facility, ONKALO, and a repository for spent nuclear fuel, at about 500m depth. Geological data acquisition plays a central role in site characterisation and modelling, and is intended to provide a solid platform on which the other disciplines (rock mechanics, hydrogeology, seismic risk assessment, etc.) can base their investigations. Based on consideration of a series of guidelines (e.g. modelling scale, source of data, level of investigation, national and international experience, special conditions at Olkiluoto, need for process understanding), a project-oriented “framework” has been developed as a background to the different projects within the geological data acquisition programme. Each project will require its own system of data acquisition (methodology, spreadsheets, protocols, etc.), as described in the corresponding reports; the present report concentrates on the general principles which lie behind the different methodologies and data sheets. These principles are treated under three main headings: characterization of intact rock (Chapter 2), characterization of deformation zone intersections (Chapter 3), and characterization of individual fractures (Chapter 4). Geological mapping of natural outcrops and trenches at Olkiluoto, and lithological logging of more than 40 rock cores, have already provided a broad basis of experience for detailed site characterisation. In addition to the lithological data acquisition, other areas of geological data acquisition are also treated here in more detail, particularly with respect to classification schemes, parameterization, and qualitative characterisation for increasing geological site understanding. Important areas which are discussed in detail include: x systematic characterisation of foliation and related small-scale heterogeneities, according to type, orientation and degree of development, including the assessment of their rock mechanics significance x identification and description of hydrothermal and other rock alteration phenomena x identification and parameterisation of deformation zone intersections, and their classification in terms of the scientifically established Sibson-Scholz fault zone model (brittle, semi-brittle, low-grade ductile and high-grade ductile deformation zone types) x detailed consideration of brittle deformation zone architecture, with particular focus on the characterisation of the core and damage zones, and kinematic parameters x classification and parameterisation of individual fractures, as a background for systematic geological studies as well as systematic data acquisition for rock quality estimation (Q-system) and Discrete Fracture Network modelling Geologisen tiedon hankinta paikkatutkimusta varten Olkiluodossa TIIVISTELMÄ "Geologinen tiedonkeruu" on yleiskäsite, joka kattaa kentällä suoraan paljaana olevasta kallioperästä (ts. luonnolliset paljastumat ja kaivannot, kairareiät sekä tunnelit ja muut maanalaiset kaivaukset) tehtävät havainnot ja mittaukset. Tässä raportissa käsitellään ainoastaan kentällä tapahtuvaa tiedonkeruuta: laboratoriotutkimuksia suoritetaan jatkos- sa kentältä kerättyjen tietojen ja näytteiden pohjalta, ja kaikki tiedot käsitellään tieteenalakohtaisesti projektin jatkuessa. Geologisen tiedonkeruun lopullinen tavoite on tuottaa tarvittava tietokanta Olkiluodon kallioperän geologisten mallien luomiseksi 500 m syvyyteen rakennettavaa maanalaista tutkimustilaa ONKALOa sekä loppusijoitus- laitosta varten. Geologinen tiedonkeruu on tärkeä osa paikkatutkimusta ja mallinnusta ja sen tavoitteena on luoda tukeva pohja muiden tieteenalojen (kalliomekaniikka, hydrogeologia, seismisten riskien arviointi jne.) tutkimuksille. Geologiseen tiedonkeruuohjelmaan kuuluvia erilaisia projekteja varten on kehitetty projektilähtöinen "runko" useiden eri ohjeistojen mukaisesti (esim. mallinnusmitta- kaava, tietolähteet, tutkimuksen taso, kotimaiset ja kansainväliset kokemukset, Olki- luodon erikoisolosuhteet, prosessin ymmärtämisen merkitys). Jokaista projektia varten tarvitaan oma tiedonkeruujärjestelmänsä (menetelmät, taulukot, protokollat, jne.), jotka on kuvattu asianomaisissa raporteissa; tämä raportti keskittyy niihin yleisperiaatteisiin, joihin eri menetelmät tukeutuvat. Näitä periaatteita käsitellään kolmen eri pääotsikon alla: ehjän kallion karakterisointi (kappale 2), deformaatiovyöhykelävistysten karakterisointi (kappale 3) ja yksittäisten rakojen karakterisointi (kappale 4). Olkiluodon luonnollisten paljastumien ja kaivan- tojen geologinen kartoitus sekä yli 40 kairasydämen litologinen kartoitus ovat jo tuottaneet laajan kokemuspohjan yksityiskohtaista paikkatutkimusta varten. Litologisen tiedon hankinnan lisäksi muita geologisen tiedonhankinnan osa-alueita käsitellään raportissa tarkemmin, varsinkin luokituksen, parametrisoinnin ja kvalitatiivisen tutkimuksen osalta geologisen paikkatietouden lisäämiseksi. Tärkeimpiä tarkemmin käsiteltäviä tutkimusalueita ovat: x liuskeisuuden ja siihen liittyvien pienimuotoisten heterogeenisyyksien syste- maattinen tutkimus tyypin, suuntauksen ja kehitysasteen perusteella, mukaan lukien niiden kalliomekaanisen merkityksen arviointi x hydrotermisten ja muiden kallion muuttumisilmiöiden identifiointi ja karakterisointi x deformaatiovyöhykkeiden leikkauskohtien identifiointi ja parametrisointi, sekä niiden tieteellinen luokitus Sibson-Scholzin siirrosmallin mukaisesti (hauraat, puolihauraat, alhaisen asteen duktiilit sekä korkean asteen duktiilit deformaatio- vyöhyketyypit) x hauraiden deformaatiovyöhykkeiden arkkitehtuurin yksityiskohtainen tutkimus, keskittyen erityisesti siirrosten ytimien sekä vaikutusalueiden karakterisointiin, sekä kinemaattisiin parametreihin x yksittäisten rakojen luokitus ja parametrisointi hyödynnettäväksi systemaattisissa geologisissa tutkimuksissa sekä systemaattisessa tiedonkeruussa kallion laadun arviointia (Q-järjestelmä) ja DFN-mallinnusta (Discrete Fracture Network) varten. 1 TABLE OF CONTENTS ABSTRACT TIIVISTELMÄ PREFACE....................................................................................................................... 3 1 BACKGROUND ...................................................................................................... 5 1.1 Introduction ..................................................................................................... 5 1.2 Geological Site Descriptive Modelling............................................................. 8 1.2.1 Step 1 - Identification, Characterisation, Parameterization (Icp)........... 10 1.2.2 Step 2 - Extrapolation, Correlation, Visualization (Ecv) ........................ 10 1.3 Starting Points............................................................................................... 11 1.3.1 Scales of Modelling ............................................................................... 11 1.3.2 Sources of Data.................................................................................... 12 1.3.3 Levels of Investigation........................................................................... 13 1.4 Guidelines ..................................................................................................... 14 1.4.1 National and International Experience .................................................. 15 1.4.2 Geological Conditions at Olkiluoto ........................................................ 15 1.4.3 Process Understanding......................................................................... 16 1.4.4 Summary............................................................................................... 16 1.5 Framework for Geological Data Acquisition.................................................. 17 2 CHARACTERISATION OF INTACT ROCK.......................................................... 21 2.1 Lithology within Rock Volumes 1000 m3 and Larger....................................
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