KIGAM 1

Overview of geological situation for a possible T2KK detector site

2006. 07. 14

Chang-Ha Ryu

Geotechnical DivisionKorea Intitute of Geoscience & Mineral Resources (KIGAM)

韓 國 地 質 資 源 硏 究 院

2nd International Workshop on a Far Detector in Korea for the J-PARC Neutrino Beam

July 13 - 14. 2006,   International Conference Hall,   SNU

KIGAM 2

General procedure

Preliminary data collection     - preliminary assessment     - preliminary geotechnical characterization

Feasibility study - engineering classification of rock mass - feasibility assessment of tunneling problems & alternatives

Detailed site characterization

Stability analyses

Final design and construction

Feedback loop

KIGAM 3

Requirements

Area between 2.0 and 2.5 degree off-axis beam ( < 1 deg. ?) Depth: ~ 1,000 m (uniform overburden in all direction) Size of underground research module: 50 m (dia.) x 280m (l)

cylindrical opening

Long term safe operation Effective (economic) construction Research module in good rock mass

KIGAM 4

JPARC

Off-axis angle

2.5deg.off-axis beam @Kamioka

2.0 deg. off axis2.0 deg. off axis

2.5 deg. off axis2.5 deg. off axis

Requirements_Location

KIGAM 5

Geology of Korea

KIGAM 6

Overview of General Geology

Throughout the country, mountains are not high, rarely exceeding 1,200 meters, but they are found almost everywhere. The terrain is rugged and steep, and only near the west and southwest coasts are extensive flat alluvial or diluvial plains and more subdued rolling hilly lands.

Korea consists largely of the Precambrian rocks, such as granite gneisses and other metamorphic rocks. The Gyeongsang Supergroup is distributed across a wide area within the Gyeongsang-do province which is one of the area of our concerns.

The Gyeongsang Supergroup is composed of the Sindong and Hwayang groups and the Bulguksa Intrusives. The biotite granite intruded in the Gyeongsang Supergroup is called Bulguksa Granite.

Hwayang Group widely distributed throughout the Gyeongsang-do province, consists of conglomerates, sandstone, shale, and volcanic rock such as andesite, basalt, rhyolite, and tuff, especially in the upper part of the group.

KIGAM 7

Site Consideration 1

Overburden: 1 km deep

Preferrable site: mountain, mine, tunnel

Easy slope topograpy requires

- excavation of long tunnel to satisfy gradient condition

- shaft, inclined shaft

too costly !

KIGAM 8

Mine Site

Advantages of utilizing abandoned mine

Reduce costs Minimize environmental impacts Minimize complaints from residents and

environmentalist Easy to get approval and

to get support from local government Easy to get information on geological conditions

KIGAM 9

URLs for Astrophysics Research_Mine SiteSoudan URLOld iron mine in MinesotaDepth : 710m (2,080mwe)Exp. Lab. : 15m x 13m x 82m

Boulby Mine Lab. - UK Location : Boulby mine, ClevelandDepth : 1,100m

CUPP Lab. - Finland Location : Outokumpu mine, PyhasalmiDepth : 90~970m (current)

SNO (Sudbury Neutrino Observatory) – CanadaLocation : Creighton mine, SudburyDepth : 2,039m

KIGAM 10

URLs for Astrophysics Research_Tunnel Site

LSC-SpainLSC-Spaininside Somport tunnel (Spain – France), Canfrancinside Somport tunnel (Spain – France), CanfrancDepth : ~ 900mDepth : ~ 900m

LNGS (Gran Sasso National Lab.) – Italybesides Gran Sasso tunnel (Teramo – Rome)Depth : 1,400m Experiment halls : L=100m, H=18m,

KIGAM 11

Site Consideration_2~2.5deg. off-axis

KIGAM 12

Site Consideration_ < 1deg. off-axis

KIGAM 13

Geological Sheets

KIGAM 14

Possible Sites

KIGAM 15

Possible Sites

KIGAM 16

Possible Site: Geological map - Eon Yang Sheet

1208m

KIGAM 17

Bohyeon San (1124m)

Site Consideration_2005

Bohyeon San in Youngcheon ~1,045 km, 2.0o off, 1124 m highNational Astronomy Observatory on top

KIGAM 18

Possible Site: <1 degree off-axis

Guryongpo in Pohang (Gyeongbuk Province) < 1,000 km < 1.0o off, no mountains (sea level)

Toham San in Gyeongju 1,000 km 1.0o off, ~500 m high mountains (National Park)

KIGAM 19

Description of Geology

EON YANG Sheet:

High mountaineous districts includes the peaks of Gajisan(1240m), Shinbulsan(1208m), in the western part, underlain by andesite, granite, and other rocks

GI GAE Sheet:

Southern marginal portion of the Taeback Mountain Range; the highest peak 960m(Giryoungsan); Bohyounsan(839m), Suseokbong(820m), Chimgoksan 725m, Unjusan 807m; the area is underlain by Cretacous sedimentary, volcanic and plutonic rocks- granite, granodiorite, andesite, rhyolite …

KIGAM 20

Geological map of GI GAE sheet _1:50000

KIGAM 21

Other Sites

SHINSHEUNG Sheet: Noreong mountain range, many peaks attain heights of betw

een 400-760m; Sinseon-bong(763m), Choowolsan; gneiss, granite, sedimentary and volcanic rocks

MIRYANG Sheet There are comparatively high peaks of Togoksan(855m), Yo

msubong(816m), Muchoksan(700m), Chontaesan(631m), Kumosan(760m), Hyangrobong(727m), Manosan(670m) etc.

The geology of the area is composed of Yuchon Group and Bulguksa Intrusive rocks. The Yuchoon group is divided into andesitic rocks (andesite, ruff), and rhyolitic rocks (rhyolite, tuff); Miryang andesite is distributed on a large scale.

KIGAM 22

Possible Site: <1 degree off-axis

Geological map – Guryogpo/Yeonil Sheet

1:50,000 geological maps of these area: unavailable

Geological data and some detailed site information available

high speed rail way construction roadway construction

KIGAM 23

Mines

  1  1     Gyeongnam-do

 1 4   1   1 Gyeongbuk-do

 2   2    Jeonnambuk-do

    1 3   8 Chungnam-do

 4 4       Chungbuk-do

 2 2  1     Gyeonggi-do

 3 7      6 5 3 1 5 Gangwon-do

 D C B A D C B A

Metal, Non-metal mine  Coal mine  Province

EX) List of Metal Mines in MUJU-gun (source: KIGAM Mine DB)가옥 , 강창 , 고길 , 금령 (2), 길산 , 동왕 (1), 무주 , 봉소(2), 삼가 (1), 삼가 (3), 삼가리 , 삼봉 (3), 삼성 (3), 세창 (2), 승륭 , 쌍봉 (1), 쌍봉 (2), 쌍봉 (3), 영성 , 오동 , 오산 (2), 월성 , 적상 , 전일 (1), 제국 (1), 창덕 (1), 태성 , 태정

Abandoned Mines

* Possibility of utilization: A>B>C>D (source: KIGAM report, 2004)

Mine layout, Samga mine

KIGAM 24

Abandoned Quarry near Miryang

Location: Gyeongsangbuk-do Cheongdo-gun Rock type: AndesiteUni-axial compressive strength: 1,500 ~ 1,600 kgf/cm2

~ 1.5 km

quarry

tunnel

KIGAM 25

Possible Site

478 m

KIGAM 26

Concluding Remarks

Possible sites - mountain area - need to investigate mines thoroughly, and then find new site

Geological conditions - favorable - if poor but no other choice, solve by engineering - more detailed geotechnical characterization needed to reduce potential risks for construction

KIGAM 27

Concluding Remarks

Factors affecting the stability of tunnels

- stress fields

- mechanical properties of rock: strength, E …

- structural characteristics: joints, faults

- groundwater conditions

- method and quality of excavation

- support of rock strata

- size and shape of tunnel, underground chamber