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Esa Poh jo la inen

October 2007

Work ing Repor t 2007 -85

Core Drilling of Borehole ONK-PVA4in ONKALO at Olkiluoto 2007

October 2007

Working Reports contain information on work in progress

or pending completion.

The conclusions and viewpoints presented in the report

are those of author(s) and do not necessarily

coincide with those of Posiva.

Esa Poh jo la inen

Suomen Ma lm i Oy

Work ing Report 2007 -85

Core Drilling of Borehole ONK-PVA4in ONKALO at Olkiluoto 2007

CORE DRILLING OF BOREHOLE ONK-PVA4 IN ONKALO AT OLKILUOTO 2007

ABSTRACT

Posiva Oy submitted an application to the Finnish Government in May 1999 for the

Decision in Principle to choose Olkiluoto in the municipality of Eurajoki as the site of the

final disposal facility for spent nuclear fuel. A positive decision was made at the end of

2000 by the Government. The Finnish Parliament ratified the decision in May 2001. The

decision makes it possible for Posiva to focus the confirming bedrock investigations at

Olkiluoto, where in the next few years an underground rock characterisation facility,

ONKALO, will be constructed. The construction of the ONKALO access tunnel started in

September 2004.

As a part of the investigations Suomen Malmi Oy (Smoy) core drilled 15.00 m long

borehole ONK-PVA4 with a diameter of 75.7 mm in ONKALO in April-May 2007. A

borehole was core drilled for long-term monitoring purposes in a place where no grouting

is done.

The deviation of the borehole was measured with the deviation measuring instrument

EMS.

The main rock types are diatexitic gneiss (DGN) and mica gneiss (MGN). The fractures

are mostly filled. The average fracture frequency of the borehole is 1.1 pcs/m and the

average RQD value is 99.4 %.

Keywords: core drilling, borehole, diatexitic gneiss, mica gneiss, fracture, deviation

measurements

REIÄN ONK-PVA4 KAIRAUS ONKALOSSA, EURAJOEN OLKILUODOSSA

2007

TIIVISTELMÄ

Posiva Oy jätti valtioneuvostolle vuonna 1999 periaatepäätöshakemuksen, jolla se haki

lupaa valita Eurajoen Olkiluoto käytetyn ydinpolttoaineen loppusijoituslaitoksen

rakennuspaikaksi. Joulukuussa 2000 valtioneuvosto teki asiasta myönteisen päätöksen.

Toukokuussa 2001 eduskunta vahvisti valtioneuvoston päätöksen. Periaate-

päätöshakemuksen mukaisesti paikkatutkimukset keskitetään Olkiluotoon.

Loppusijoituslaitoksen maanalaisen kallioperäntutkimustilan, ONKALOn, ajotunnelin

rakentaminen aloitettiin Olkiluodossa syyskuussa 2004.

Seurannalla pyritään myös selvittämään sementin vaikutusta pohjavesikemiaan eri

etäisyyksillä tunnelista. Osana tutkimuksia Suomen Malmi Oy (Smoy) kairasi 15,00 m

pitkän reiän (ONK-PVA4) ONKALOssa huhti-toukokuussa 2007. Reikä kairattiin

pohjavesien pitkäaikaista monitorointia varten paikkaan, missä ei ole injektoitu. Reiän

tarkoitus on tutkia rakentamisen aiheuttamia muutoksia pohjaveteen. Reiän halkaisija on

75,7 mm.

Reiän taipumat mitattiin EMS -mittarilla.

Pääkivilajeina esiintyvät diateksiittinen gneissi (DGN) ja kiillegneissi (MGN).

Rakoilutyyppinä täytteiset raot ovat yleisimpiä. Kallion rakoluku on keskimäärin 1,1

kpl/m. RQD-luku on keskimäärin 99,4 %.

Avainsanat: kairaus, kairanreikä, diateksiittinen gneissi, kiillegneissi, rako,

sivusuuntamittaus

1

TABLE OF CONTENTS

ABSTRACT

TIIVISTELMÄ

1. INTRODUCTION ................................................................................................ 31.1 Background ............................................................................................. 31.2 Scope of the work ................................................................................... 3

2. DRILLING WORK AND TECHNICAL DETAILS OF THE BOREHOLE .............. 52.1 Diamond core drilling .............................................................................. 52.2 Deviation surveys.................................................................................... 52.3 Location and deviation ............................................................................ 62.4 Construction of the upper part of the borehole........................................ 6

3. GEOLOGICAL LOGGING................................................................................... 73.1 General ................................................................................................... 73.2 Lithology.................................................................................................. 73.3 Foliation................................................................................................... 83.4 Fracturing ................................................................................................ 93.5 Fracture frequency and RQD ................................................................ 163.6 Weathering............................................................................................ 173.7 Core orientation..................................................................................... 18

4. ROCK MECHANICS......................................................................................... 194.1 The rock quality..................................................................................... 19

5. SUMMARY........................................................................................................ 21

6. REFERENCES ................................................................................................. 23

7. APPENDICES 7.1 List of core boxes .................................................................................. 25 7.2 List of lifts .............................................................................................. 27 7.3 Deviation surveys, list, EMS.................................................................. 29 7.4 Petrographical description..................................................................... 31 7.5 Degree of weathering ........................................................................... 33 7.6 Foliation................................................................................................. 35 7.7 List of fractures...................................................................................... 37 7.8 Fracture frequency and RQD ................................................................ 39 7.9 Core orientation..................................................................................... 41 7.10 Q-classification...................................................................................... 43

PHOTOS ...................................................................................................................... 45

2

1. INTRODUCTION

1.1 Background

In 1999, Posiva Oy submitted an application for the Decision in Principle to Finnish

Government for a construction permit to build a final disposal facility for spent fuel at the

Olkiluoto area in the Eurajoki municipality. In December 2000, the Finnish Government

made a positive policy decision and in May 2001, the parliament ratified the Decision in

Principle.

The Decision in Principle makes it possible to concentrate the research activities at

Olkiluoto, Eurajoki. One part of the research is to build an underground rock

characterisation facility, ONKALO. The construction of the ONKALO access tunnel

started in September 2004.

Posiva Oy contracted (order number 9249-07) Suomen Malmi Oy (Smoy) to drill a

borehole in the ONKALO. The identification number of the borehole is ONK-PVA4. A

borehole was core drilled for long-term monitoring purposes in a place where no grouting

is done. The objective with the borehole is to monitor the influences of construction at

ONKALO. A borehole was core drilled in April-May 2007.

1.2 Scope of the work

The aim of the work was to drill a borehole related to the investigation programme on the

influence of grouting in groundwater chemistry and monitor the influences of

construction at ONKALO. The core samples were logged according to the geological

instructions of Posiva. To maximise the recovery yield of an undisturbed and continuous

core, triple tube coring technique was used. In addition to the drilling, work included core

logging, borehole deviation surveys and reporting.

This report documents the work and sampling done during the drilling of the borehole.

Depth measurements are from the tunnel floor surface unless otherwise stated.

3

4

2. DRILLING WORK AND TECHNICAL DETAILS OF THE BOREHOLE

2.1 Diamond core drilling

The diamond drilling was done in April-May 2007. The borehole was started at tunnel

floor. First the casing was drilled to the depth of about one metre into the bedrock. After

the casing was drilled, diamond core drilling continued normally.

Borehole was core drilled with a hydraulic Diamec U6 drill rig. NQ3 -triple tube core

barrel and NQ-drill rods were used in drilling. Borehole diameter with NQ3 -triple tube

core barrel is 75.7 mm and drill core diameter is 50.2 mm. After finishing the work, the

casing was left in the borehole. After drilling, the Posiva Oy measured the amount of

water flowing from borehole, which was under 10 mm/h.

The cutting area of the diamond bit of the triple tube core barrel is larger than that of the

double tube core barrel. In the triple tube core barrel the third, innermost, tube is of split

type. The innermost split tube containing the sample is removed from the core barrel with

the aid of a piston working on water pressure. In this way the sample may be removed

from the core barrel as undisturbed as possible.

Drilling team in a shift consisted of a driller and an assistant. Geological logging was

done by geologists Esa Pohjolainen and Vesa Toropainen and the final report was

compiled by Esa Pohjolainen.

Drill core samples were placed in wooden core boxes immediately after emptying the

core barrel. In total, four wooden core boxes were used during this drilling work. Start

and end depths of the core in each core box are presented in Appendix 3.10. Wooden

blocks separating the different sample runs were placed to core boxes to show the depth

of each lift. The core drilling included six sample runs or lifts. Depths of lifts are

presented in Appendix 2.2.

2.2 Deviation surveys

To trace the borehole accurately the dip and the azimuth of borehole were measured with

EMS downhole deviation survey tool. Measuring interval was three metres.

5

EMS device measures the borehole dip with an electronic accelerometer and the azimuth

relative to the magnetic north with a three component fluxgate magnetometer. According

to the manufacturer, provided there are no magnetic anomalies, the accuracy of the

azimuth is ± 0.5 degrees and the accuracy of the dip is ± 0.2 degrees. The azimuth is

given to the magnetic north and the declination. There may be some local variations in the

declination. Used declination in EMS calculations is 4.0 degrees.

2.3 Location and deviation

The bedrock surface of the tunnel floor was used as the reference level for depth

measurements. The initial dip of borehole is downwards, about -60 degrees from

horizontal. The coordinates of the boreholes in the Finnish coordinate system are shown

in Table 1. The collar coordinates were measured by the Posiva. The coordinates at the

end of the borehole are based on the EMS data. The results of the EMS surveys are listed

in Appendix 7.3.

Table 1. Coordinates of the borehole.

Station (m) X Y Z

0 6792258.50 1525972.07 -138.19

3 6792257.91 1525973.45 -140.79

6 6792257.35 1525974.84 -143.39

9 6792256.81 1525976.23 -145.99

12 6792256.26 1525977.62 -148.59

2.4 Construction of the upper part of the borehole

The borehole was collared with 89/78 mm acid-resistant steel casing to the depth about

one metre from the tunnel wall surface. When the borehole was finished, the casing was

left in the borehole.

6

3. GEOLOGICAL LOGGING

3.1 General

Handling of the core was based on the POSIVA work instructions POS-001427 ”Core

handling procedure with triple tube coring (in Finnish)”. Drill core samples were placed

in about one metre long wooden core boxes immediately after emptying the core barrel.

Core boxes were covered with damp proofing quality aluminium paper so that the

aluminium surface was against the core. Also the wooden blocks separating the different

sample runs were covered by aluminium paper. Drill core was handled carefully during

and after the drilling. Core was placed in the boxes avoiding any unnecessary breakage.

The core logging of ONK-PVA4 followed the normal Posiva logging procedure, which

has been used e.g. in pilot hole drilling programmes at Olkiluoto. Geologists Esa

Pohjolainen and Vesa Toropainen carried out the geological core logging. From the core

samples the lithology, foliation, fracturing, fractured zones, weathering and rock quality

were mapped. All core boxes were photographed (colour) both dry and wet. Core

photographs (wet) are presented at the end of the report. List of core boxes lists the start

and end depths of the core in each core box (Appendix 7.1).

List of lift depths is given as it has been marked on the spacing wooden blocks separating

different sample runs in the core boxes. If the length of the core in the core barrel

indicated that sampling depth was different from the depth recorded during drilling, the

true sample depth has been corrected on the spacing block. Therefore, the sample run

depth means the sample depth. The drilling depth might be deeper than the sampling

depth if the core lifter slips and part of the core is left in the borehole and is not retrieved

until with the next lift.

3.2 Lithology

The lithological classification used in the mapping follows the classification by Mattila

(2006). In this classification, migmatitic metamorphic gneisses are divided into veined-

(VGN), stromatic- (SGN) and diatexitic gneisses (DGN). The non-migmatitic

metamorphic gneisses are separated into mica- (MGN), mafic- (MFGN), quartz- (QGN)

and tonalitic-granodioritic-granitic gneisses (TGG). The metamorphic rocks form a

compositional series which can be separated by rock texture and the proportion of

7

leucosome. Igneous rock names used in the classification are coarse-grained pegmatitic

granite (PGR), K-feldspar porphyry (KFP) and diabase (DB).

The ONK-PVA4 drill core consists mostly of diatexitic gneiss (87.4 %). A section of

MGN (12.6 %) occurs between 10.27-12.16 m. The DGN is irregularly and weakly or

moderately banded. The leucosome proportion in DGN varies between 50-75 %, most of

the rock being ca. 60 %. The feldspars are slightly kaolinitized and epidotized between

3.70-4.36 m. The lithology recorded from the core is presented in Appendix 3.1.

3.3 Foliation

Measurements on foliation were carried out in variable intervals from the core sample. A

total of six observations on foliation were made. The classification of the foliation type

and intensity used in this study is based on the characterisation procedure introduced by

Milnes et al. (2006). Foliation type was estimated macroscopically and classified into

five categories:

MAS = massive

GNE = gneissic

BAN = banded

SCH = schistose

IRR = irregular

The gneissic type (GNE) corresponds to a rock dominated by quartz and feldspars, micas

and amphiboles occur only as minor constituents. Banded foliation type (BAN) consists

of intercalated gneissic and schistose layers, which are either separated or discontinuous

layers of micas or amphiboles. Schistose type (SCH) is dominated by micas or

amphiboles, which have a strong orientation.

The intensity of the foliation is based on visual estimation and classified into the

following four categories:

0 = Massive or irregular

1 = Weakly foliated

2 = Moderately foliated

3 = Strongly foliated

8

The two variables (type and intensity) can be combined in a matrix, which is constructed

to reflect the mechanical properties of the rock. Massive (MAS) corresponds to massive

rock with no visible orientations and irregular (IRR) to folded or chaotic rock.

The foliation type in the predominant rock type, DGN, is banded (87.4 %). A section of

MGN between 10.27-12.16 m consists of gneissic type (12.6 %). The most common

foliation direction is towards southeast (150/40) as shown in Figure 3-1.

Figure 3-1. Measured foliation orientations of ONK-PVA4 on an equal area lower

hemisphere projection. Contours presented are 2, 5, 10, 20 and 30 %.

3.4 Fracturing

The fractures were numbered sequentially from the top to the bottom of the borehole.

Fracture depths were measured to the centre line of the core and were given with one

centimetre accuracy. Each fracture was described individually and attributes include

orientation, type, colour, fracture filling, surface shape and roughness. The Ja (joint

alteration) and Jr (joint roughness) parameters for the Q-classification were also collected

for each fracture. The abbreviations used to describe the fracture type are in accordance

with the classification used by Suomen Malmi Oy (Niinimäki 2004), Table 3-1.

9

Table 3-1. The abbreviations used to describe the fracture type (Niinimäki 2004).

Abbreviation Fracture type

op open

ti tight, no filling material

fi filled

fisl filled slickensided

grfi grain filled

clfi clay filled

The fractures, which had a fracture filling and a clear colour but the core was intact across

the fractures, were classified as filled. Filled fractures with intact surfaces were described

as closed or partly closed. In these cases in the remarks column has been written ”closed”

or ”partly closed”, which indicates that the fracture is healed or partly healed and its

permeability is poor in its natural state. The thickness of the filling was estimated with an

accuracy of 0.1 mm. The recognition of fracture fillings is qualitative and visually

estimated. Where the recognition of the specified mineral was not possible, the mineral

was described with a common mineral group name, such as clay and sulphides, in

accordance with the fracture mineral database which Kivitieto Oy and Posiva Oy have

developed (Table 3-2). Abbreviations were used during the loggings.

Table 3-2. The list of the mineral abbreviations.

Abbreviation Mineral Abbreviation MineralAN = analcime NA = nakrite KS = kaolinite + other

clay minerals HB = hydrobiotite

BT = biotite PA = palygorsgite LM = laumontite HE = hematite CC = calcite PB = galena MH = molybdenite IL = illite CU = chalcopyrite SK = pyrite MK = pyrrhotite IS = illite + other clay

minerals DO = dolomite SM = smectite MO = montmorillonite KA = kaolinite EP = epidote SR = sericite MP = black pigment KI = kaolinite + illite FG = phlogopite SV = clay mineral MS = feldspar KL = chlorite GR = graphite VM = vermikulite MU = muscovite KM = K-feldspar GS = gismondite ZN = sphalerite

10

The fracture surface shapes and roughness are classified using modification of Barton’s

(Barton et al. 1974) Q-classification (Table 3-3). In addition to this, the fracture

morphology and fracture alteration were also classified according to the Q-system

(Grimstad & Barton 1993). Fracture roughness was described with the joint roughness

number, Jr (Table 3-4) and the fracture alteration with the joint alteration number, Ja

(Table 3-5).

Table 3-3. The fracture surface shapes and roughness (Barton et al. 1974).

Fracture shape Fracture roughness

Planar Rough

Stepped Smooth

Undulated Slickensided

Table 3-4. The concise description of joint roughness number Jr (Grimstad & Barton

1993).

Jr Profile i) Rock wall contact ii) Rock wall contact before 10 cm shear.

4 SRO Discontinuous joint or rough and stepped

3 SSM Stepped smooth

2 SSL Stepped slickensided

3 URO Rough and undulating

2 USM Smooth and undulating

1,5 USL Slickensided and undulating

1,5 PRO Rough or irregular, planar

1 PSM Smooth, planar

0,5 PSL Slickensided, planar

Note1. Descriptions refer to small scale features and intermediate scale features, in that order.

Jr No rock-wall contact when sheared

1 Zone containing clay minerals thick enough to prevent rock-wall contact

1 Sandy, gravely or crushed zone thick enough to prevent rock-wall contact

Note1. Add 1 if the mean spacing of the relevant joint set is greater than 3. 2. Jr = 0,5 can be used for planar slickensided joints having lineation, provided the lineations are oriented for minimum strength.

11

Table 3-5. The concise description of joint alteration number Ja (Grimstad & Barton 1993).

Ja Rock wall contact (no mineral filling, only coatings).

0,75 Tightly healed, hard, non-softening impermeable filling, i.e. quartz, or epidote.

1 Unaltered joint walls, surface staining only.

2 Slightly altered joint walls. Non-softening mineral coatings, sandy particles, clay-free disintegrated rock, etc.

3 Silty or sandy clay coatings, small clay fraction (non-softening).

4 Softening or low-friction clay mineral coatings, i.e. kaolinite, mica, chlorite, talc, gypsum, and graphite, etc., and small quantities of swelling clays (discontinuous coatings, 1-2 mm or less in thickness.

Rock wall contact before 10 cm shear (thin mineral fillings).

4 Sandy particles, clay-free disintegrated rock, etc.

6 Strongly over-consolidated, non-softening clay mineral fillings (continuous, <5 mm in thickness).

8 Medium or low over-consolidation, softening, clay mineral filling (continuous <5 mm in thickness).

8-12 Swelling-clay fillings, i.e. montmorillonite (continuous, <5 mm in thickness). Value of Ja depends on percentage of swelling clay-sized particles, and access to water, etc.

No rock-wall contact when sheared (thick mineral fillings).

6-12 Zones or bands of disintegrated or crushed rock and clay.

5 Zones or bands of silty- or sandy-clay, small clay fraction (non-softening).

10-20 Thick, continuous zones or bands of clay.

During the fracture logging the surface colour was registered, the colour often caused by

the dominating fracture filling mineral or minerals, e.g. chlorite (green) or kaolinite

(white). Existence of minor filling minerals usually causes some variation in the colour of

the fracture surface. These shades were described e.g. as reddish or greenish. Tight

fractures had typically only a slightly different shade from the host rock colour.

In the fracture mapping a total of 17 fractures were recorded, Appendix 3.3. There are 13

filled fractures (76.5 %), three tight fractures (17.6 %) and one filled slickensided fracture

(5.9 %). Of the 13 filled fractures, two are closed fractures and one is partly closed

fracture. The frequencies of fracture surface qualities and morphologies and both joint

roughness and joint alteration numbers are shown as histograms in Figures 3-2, 3-3, 3-4

and 3-5.

The fractures are mainly undulated by shape (Figure 3-2). Most of the fractures have

rough profile (Figure 3-3) and have high joint roughness number (Figure 3-4), indicating

a high friction in the fracture surface. Low joint alteration numbers (Figure 3-5) also

support this conclusion. The fracture fillings are mainly calcite, pyrite and kaolinite.

12

Minor occurrences of chlorite and clay minerals were also recorded. A slickensided

surface contained calcite and clay material.

Fracture shape

1

10

6

0

2

4

6

8

10

12

stepped undulated planar

Figure 3-2. Histogram of fracture shape.

Fracture roughness

16

1

0

0

2

4

6

8

10

12

14

16

18

rough smooth slickensided

Figure 3-3. Histogram of fracture roughness.

13

Joint roughness number

0 0

6

1

9

1

0

1

2

3

4

5

6

7

8

9

10

0,5 1 1,5 2 3 4

Figure 3-4. Histogram of joint roughness number.

Joint alteration number

2

10

4

1

0 0 0

0

2

4

6

8

10

12

0,75 1 2 3 4 5 6

Figure 3-5. Histogram of joint alteration number.

14

During the drilling, total three of qualified orientation marks were made. One (2.36 m) of

these marks was discarded because of contradiction in comparison with other two marks.

Still, 98.3 % of the whole drill core was orientated. The base line drawn from these marks

onto the drill core acted as a ground for the measurements from the sample. From the

oriented drill core sections core alpha and beta angles of every fracture were measured

(Figure 3-6, Appendix 3.3). Each alpha and beta value was recalculated to real dip and dip

directions using drill hole orientation and hole deviation survey data.

The most common fracture direction is towards northeast (025/70). There is a minor

fracture direction towards northwest with steep dip (325/88). The directions have been

corrected using the directional survey data of EMS instrument. Fracture orientation is

shown on an equal area lower hemisphere projection in Figure 3-7.

Figure 3-6. The fracture orientation measurements from orientated core. The core

alpha ( ) angle measured relatively to core axis. The core beta ( ) angle measured

clockwise relatively to reference line looking downward core axis in direction of

drilling. Figure modified from Rocscience Inc. Borehole orientation data pairs, Dips (v.

5.102) Help.

15

Figure 3-7. Fracture orientation data of all the oriented fractures on an equal area

lower hemisphere projection. Contours presented are 2, 4, 6, 8, 10, 12 and 14 %.

3.5 Fracture frequency and RQD

Natural fracture frequency, break frequency and RQD were logged on full metre depth

intervals. Break frequency is the number of core breaks within one metre interval.

Drilling, core handling, core discing and natural fractures cause breaks. Fracture

frequency is the number of natural fractures within one metre interval. If the break

frequency is higher than the natural fracture frequency the core must have been broken

during the drilling or core handling accidentally or by purpose. If the natural fracture

frequency is higher than the break frequency the fractures must be cohesive enough to

keep the core together. RQD gives the percentage of over 10 cm long core segments,

which are separated by natural fractures, within one metre interval.

The average fracture frequency of the borehole is 1.1 pcs/m and the average RQD value is

99.4 %. Fracture frequency and RQD are shown graphically in Figure 3-8 and also

presented in Appendix 3.7.

16

Fracture frequency and RQD

0

1

2

3

4

5

6

7

8

9

10

1 11

Fra

ctu

res/

met

re

0

10

20

30

40

50

60

70

80

90

100

RQ

D

NAT FRACTURES pieces/m RQD %

Figure 3-8. Frequency of natural fractures and RQD along the ONK-PVA4.

3.6 Weathering

The weathering degree of the drill core was classified according to the method developed

by Korhonen et al. (1974) and Gardemeister et al. (1976) and the abbreviations are

presented in Table 3-6.

Table 3-6. The abbreviations of the weathering degree.

Abbreviation Description of weathering type

Rp0 unweathered

Rp1 slightly weathered

Rp2 strongly weathered

Rp3 completely weathered

Most of the drill core is unweathered, having only slightly pinitized cordierite grains.

Only the rock section between 3.70-4.36 m is slightly weathered, where occur some

kaolinitization and epidotization of feldspars. The weathering degree along the ONK-

PVA4 is presented in Appendix 3.9.

17

3.7 Core orientation

The depth of each run where the core has been orientated has been recorded. Also the start

and end depths and the length of the orientated part of the sample have been marked. If

the mark has been rejected, there is a comment of this in the list.

Core orientation was carried out by lowering a hinged marking spike in the hole with a

wire. The spike lies against the bottom of the hole and makes a mark at the bottom of the

hole. In the next run the mark will be at the upper end of the core sample and the sample

may be orientated utilizing the directional information of the hole. Orientation of samples

was utilized in determining the direction of fractures and other linear features in the core.

The aim was to orientate as much core as possible in order to measure geological features.

In ONK-PVA4, three orientation operations were carried out. One (2.36 m) of these

marks was rejected because of contradiction in comparison with other two marks. In total,

14.74 meters (98.3 %) of orientated sample was collected. The results are shown in

Appendix 3.6.

18

4. ROCK MECHANICS

4.1 The rock quality

The rock quality is classified using Barton’s Q-classification (Rock Tunneling Quality

Index, Barton, 1974 and Grimstad & Barton, 1993) during the core logging. The Q-

classification was used as basis for the rock mechanical logging. The core was visually

divided into sections based on the Q-value, the lengths of which can vary from less than a

metre to several metres. In each section the rock quality is as homogenous as possible.

The roughness and alteration numbers are estimated for each fracture surface and for each

section the roughness and alteration numbers are calculated (average, median and lower

and higher quartiles) and the median value is used in the Q-quality calculations. The

roughness and alteration numbers are listed in the fracture table, Appendix 3.3. RQD is

defined as the cumulative length of core pieces longer than 10 cm in a run divided by the

total length of the core run.

Q-value is calculated by equation (Barton, 1974 and Grimstad & Barton, 1993):

SRF

J

J

J

J

RQDQ w

a

r

n

**

Some constant values have been used. All fractures, which are closed, are classified in

joint alteration (Ja) as number 0.75. These closed fractures are counted as well in RQD

value. In calculations joint water (Jw) and stress reduction factors (SRF) are assumed to 1.

Results (Q) are presented in Appendix 4.1.

According to Barton’s Q-classification, the rock quality in ONK-PVA4 is very good. The

rock section is composed of diatexitic gneiss (87.4 %) and mica gneiss (12.6 %), which

are very intact containing just a few fractures.

19

Figure 4-1. Description of RQD and joint set number Jn (Grimstad & Barton 1993).

20

5. SUMMARY

Finnish parliament has ratified the Decision in Principle (the final disposal facility for

spent nuclear fuel at Olkiluoto, Eurajoki) in May 2001. The decision makes it possible

for Posiva Oy to concentrate its site investigations for the underground final disposal

facility for spent fuel at Olkiluoto in Eurajoki. Within the next few years, an underground

rock characterisation facility, ONKALO, will be built at Olkiluoto.

As a part of these investigations, Suomen Malmi Oy drilled a borehole ONK-PVA4 in

ONKALO for long-term monitoring purposes in a place where no grouting is done. The

deviation of the borehole was measured with EMS -deviation survey tool.

The ONK-PVA4 drill core is composed of diatexitic gneiss (87.4 %) and mica gneiss

(12.6 %). The DGN contains biotite-rich schlierens and large amounts of cordierite grains,

which are pinitized with a variable degree. A section of MGN occurs between 10.27-

12.16 m. The DGN is irregularly and weakly or moderately banded and most of its length

in the core is very intact. The leucosome proportion in DGN varies between 50-75 %,

most of the rock being ca. 60 %.

The rock is mostly unweathered or only slightly weathered. The feldspars are slightly

kaolinitized and epidotized between 3.70-4.36 m. The foliation type in the predominant

rock type, DGN, is banded (87.4 %). There is a section of gneissic type in MGN between

10.27-12.16 m.

Filled fracture is the most common type of fracture. In the fracture mapping a total of 17

fractures were recorded. There are 13 filled fractures (76.5 %), three tight fractures (17.6

%) and one filled slickensided fracture (5.9 %). Of the 13 filled fractures, two are closed

fractures and one is partly closed fracture.

The average fracture frequency of the borehole is 1.1 pcs/m and the average RQD value is

99.4 %. The fractures are mainly undulated by shape and rough by profile. The fracture

fillings are mainly calcite, pyrite and kaolinite. According to Barton’s Q-classification, the

rock quality of the ONK-PVA4 is very good.

21

22

6. REFERENCES

Barton, N., Lien, R. & Lunde, J. 1974. Engineering classification of rock masses for the

design of tunnel support. Rock Mechanics. December 1974. Vol. 6 No. 4. Springer

Verlag. Wien, New York. 189-236 pp.

Barton, N. & Choubey, V., 1977. The shear strength of rock joints in theory and practice.

Rock Mechanics 1, s. 1 – 54. Springer-Verlag.

Gardemeister, R., Johansson, S., Korhonen, P., Patrikainen, P., Tuisku, T. & Vähäsarja, P.

1976. Rakennusgeologisen kallioluokituksen soveltaminen. (The application of Finnish

engineering geological bedrock classification, in Finnish). Espoo: Technical Recearch

Centre of Finland, Geotechnical laboratory. 38 p. Research note 25.

Grimstad, E. & Barton, N. 1993. Updating of the Q-system for NMT. Proceedings of

Sprayed Concrete, 18-21 December 1993. Fagernäs. Norway

ISRM. 1981. Suggested Methods for Determining the Uniaxial Compressive Strength and

Deformability of Rock Materials. In Rock Characterization Testing & Monitoring.

Oxford, Pergamon Press. s. 113-116.

ISRM. 1985. Suggested Method for Determining Point Load Strength. International

Journal Rock Mech. Min. Sci. & Geomech. Vol. 22, no 2. S. 51-60.

Korhonen, K-H., Gardemeister, R., Jääskeläinen, H., Niini, H. & Vähäsarja, P. 1974.

Rakennusalan kallioluokitus. (Engineering geological bedrock classification, in Finnish).

Espoo: Technical Research Centre of Finland, Geotechnical laboratory. 78 p. Research

note 12.

Kärki. A. & Paulamäki, S., Petrology of Olkiluoto. POSIVA 2006-02. Posiva Oy,

Eurajoki.

Mattila, J. 2006. A System of Nomenclature for Rocks in Olkiluoto. Eurajoki, Finland:

Posiva Oy. Posiva Working report 2006-32.

23

Milnes, A. G., Hudson, J., Wikström, L. & Aaltonen, I. 2006. Foliation: Geological

Background, Rock Mechanics Significance, and Preliminary Investigations at Olkiluoto.

Working Report 2006-03. Posiva Oy, Eurajoki.

Niinimäki, R. 2004. Core drilling of Pilot Hole OL-PH1 at Olkiluoto in Eurajoki 2003-

2004. Eurajoki, Finland: Posiva Oy. Posiva Working report 2004-05, 95 p.

Pohjanperä, P., Wanne, T. & Johansson, E. 2005. Point load test results from Olkiluoto

area – Determination of strength of intact rock from boreholes KR1-KR28 and PH1.

Working Report 2005 -59. Posiva Oy, Eurajoki.

Saltikoff, B. 1972. Mineraalinimisanasto. Espoo, Geological Survey of Finland. Report of

Investigation N:o 11 (in Finnish). 82 pages. ISBN 951-690-044-5.

24

BOX M FROM M TO

NUMBER m m

1 0.00 4.35

2 4.35 8.99

3 8.99 13.38

4 13.38 15.00

25List of core boxes, ONK-PVA4 Appendix 7.1

26

LIFT NR LIFT DEPTH LENGTH REMARKS

m m

0 0.00 Start of drilling

1 2.36 2.36

2 5.38 3.02

3 8.39 3.01

4 11.52 3.13

5 12.46 0.94

6 15.00 2.54

27List of lifts, ONK-PVA4 Appendix 7.2

28

Suomen Malmi Oy

P.O.Box 10

FIN-02921 ESPOO

Client: Posiva Hole No: ONK-PVA4 Diameter: NQ3

Site: Olkiluoto X: 6 792 258.50 Lenght: 12

Project No: Y: 1 525 972.07 Azimuth: 113.50

Z: -138.19 Dip: -59.95

Station Dip Azimuth

0 -59.95 113.50

3 -60.08 112.50

6 -60.06 111.50

9 -60.14 111.35

12 -60.16 111.64-148.59

-138.19

-140.79

-143.39

-145.99

1 525 972.07

1 525 973.45

1 525 974.84

1 525 976.23

Easting

6 792 256.81

6 792 256.26

EMS-survey

Northing

6 792 258.50

6 792 257.91

6 792 257.35

Depth

1 525 977.62

29Deviation surveys, list, EMS,ONK-PVA4

Appendix 7.3

30

M FROM M TO ROCK TYPE LEUCOSOME % DESCRIPTION

m m

0.00 10.27 DGN 60 Irregularly and moderately banded diatexitic gneiss containing ca. 50-70 % leucosome. Some parts

are more intensively banded, especially mesosome-rich parts. The DGN contains biotite-rich

schlierens and large amounts of cordierite grains, which are pinitized with variable degree. Some

sillimanite in biotite-rich parts. Disseminated pyrite in some places.

10.27 12.16 MGN 0 Uniform and massive MGN section. Main minerals are feldspars, biotite and quartz.

12.16 15.00 DGN 60 Weakly and irregularly banded diatexitic gneiss containing ca. 50-75 % leucosome. Some pinitized

cordierite in leucosome, also small amounts of apatite and garnet in places.

31Petrographical description,ONK-PVA4

Appendix 7.4

32

M FROM M TO WEATHERING Remarks

m m DEGREE

0.00 3.70 Rp0 Some pinitized cordierite

3.70 4.36 Rp1 Kaolinitization and epidotization of feldspars

4.36 15.00 Rp0 Some pinitized cordierite

33Degree of weathering,ONK-PVA4

Appendix 7.5

34

M FROM M TO ELEMENT DEPTH DIP DIR DIP ALPHA BETA FOLIATION FOLIATION METHOD ROCK TYPE REMARKS

m m m (°) (°) TYPE INTENSITY

0.00 10.27 BAN 2 DGN

FOL 1.47 34 37 40 130 BAN 2 Sample DGN

FOL 2.82 19 5 60 170 BAN 2 Sample DGN

FOL 5.12 114 22 38 180 BAN 2 Sample DGN

FOL 7.77 146 35 28 200 BAN 2 Sample DGN

FOL 10.08 193 37 40 230 BAN 2 Sample DGN

10.27 12.16 GNE 1 MGN

12.16 15.00 BAN 1 DGN

FOL 14.62 151 39 25 205 BAN 1 Sample DGN

35Foliation, ONK-PVA4 Appendix 7.6

36

FR

AC

TU

RE

DE

PT

HC

OR

E A

LP

HA

CO

RE

BE

TA

CO

RE

GA

MM

AC

OR

E D

IRC

OR

E D

IPC

OL

OU

R O

FF

RA

CT

UR

ET

HIC

KN

ES

S O

F

TY

PE

FR

AC

TU

RE

FR

AC

TU

RE

Jr

Ja

CL

AS

S O

F T

HE

RE

MA

RK

S

NU

MB

ER

m(°

)(°

)(°

)(°

)(°

)F

RA

CT

UR

E S

UR

FA

CE

FIL

LIN

GF

ILL

ING

(m

m)

SH

AP

ER

OU

GH

NE

SS

31

FR

AC

TU

RE

D Z

ON

E

11

.49

50

90

35

34

8w

hite

KA

0.2

fiu

nd

ula

ted

rou

gh

31

22

.24

40

60

33

96

9ti

pla

na

rro

ug

h1

.51

35

.06

45

40

32

27

0ti

un

du

late

dro

ug

h3

1

46

.23

50

18

01

14

10

wh

ite

KA

, S

K,

CC

0.3

fiu

nd

ula

ted

rou

gh

31

56

.55

45

15

55

72

1w

hite

KA

, S

K0

.4fi

un

du

late

dro

ug

h3

2

66

.83

13

10

53

07

1lig

ht

bro

wn

SK

0.5

fiu

nd

ula

ted

rou

gh

30

.75

clo

se

d

76

.96

18

10

02

37

0lig

ht

bro

wn

SK

0.4

fiu

nd

ula

ted

rou

gh

30

.75

clo

se

d,

bra

nch

ed

87

.62

62

11

03

49

32

tiu

nd

ula

ted

rou

gh

31

98

.15

54

55

32

85

8lig

ht

bro

wn

SK

0.1

fip

lan

ar

rou

gh

1.5

1

10

8.2

15

03

25

27

06

6lig

ht

bro

wn

SK

0.1

fip

lan

ar

rou

gh

1.5

1

11

8.6

93

03

03

19

87

ligh

t b

row

nS

K,

CC

0.2

fiu

nd

ula

ted

rou

gh

31

12

9.4

02

55

03

38

86

ligh

t b

row

nS

K0

.3fi

un

du

late

dro

ug

h3

1

13

10

.34

28

30

32

08

9lig

ht

gra

yC

C,

SK

0.3

fip

lan

ar

rou

gh

1.5

2

14

11

.21

20

90

13

73

ligh

t, g

ree

nC

C,

SK

, K

L0

.4fi

pla

na

rro

ug

h1

.52

15

13

.32

15

95

20

75

ligh

t b

row

nS

K,

CC

0.9

fip

lan

ar

rou

gh

1.5

2p

art

ly c

lose

d

16

13

.35

45

29

52

47

62

ligh

t g

ray

CC

0.1

fiste

pp

ed

rou

gh

41

inte

rse

cte

d b

y p

revio

us f

ractu

re

17

14

.73

15

85

65

12

80

gra

yC

C,

SV

0.7

fisl

un

du

late

dsm

oo

th2

3

37List of fractures, ONK-PVA4 Appendix 7.7

38

M FROM M TO ALL FRACTURES NAT FRACTURES RQD Remarks

m m pieces/m pieces/m %

0 1 9 0 100

1 2 2 1 100

2 3 4 1 100

3 4 3 0 100

4 5 1 0 100

5 6 2 1 100

6 7 2 4 100 Two of the four natural fractures are closed

7 8 3 1 100

8 9 5 3 94

9 10 3 1 100

10 11 3 1 100

11 12 4 1 100

12 13 1 0 100

13 14 1 2 97 One of the two natural fractures is partly closed

14 15 2 1 100

39Fracture frequency and RQD,ONK-PVA4

Appendix 7.8

40

MARK NR MARK DEPTH M FROM M TO LENGTH REMARKS

m m m

1 2.36 mark rejected

2 5.38 0.26

3 11.52 15.00 14.74

41Core orientation, ONK-PVA4 Appendix 7.9

42

M FROM M TO LENGTH OF > 10 cm Number of RQD RQD Jn Q PRIME Q PRIME CLASS OF THE CORE Q PRIME REMARKS

m m SECTION cm fractures % >10 profile median median NUMBER CLASS FRACTURED ZONE LOSS (m)

0.00 15.00 15 1491 17 99.4 99.4 3 URO 3.0 1.00 99.4 Very Good

Jr Ja

43Q-classification, ONK-PVA4 Appendix 7.10

44

45

46

47

48