The Evaluation of Rock Mass Deformation Characteristics at Deep Depth in Granite using a Pressuremeter Test

Dae-Sung Cheon; Jai-Yong Park; Won-Kyong Song; Ki Seog Kim

doi:10.7474/TUS.2024.34.6.636

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2024 Vol.34, Issue 6 Preview Page Next Page

Technical Note

The Evaluation of Rock Mass Deformation Characteristics at Deep Depth in Granite using a Pressuremeter Test 공내재하시험을 통한 화강암반의 대심도 변형 특성 평가

31 December 2024. pp. 636-649

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Abstract

A high-level radioactive waste disposal facility is expected to be constructed at a depth of at least 300 m within deep bed rock. The deformation of bed rock significantly impacts the stability of such disposal facilities as well as other general geotechnical structures. Therefore, understanding the deformation characteristics of rock at the disposal depth is important for high-level radioactive waste disposal facilities. However, in Korea, due to limitations in application target and equipment, deformation measurements have so far been conducted only in shallow depths or predicted using estimation formula. In this study, a deep pressuremeter testing device based on a high-pressure dilatometer was used to conduct tests up to a depth of 449 m, obtaining shear modulus and deformation modulus. The tests were performed in a borehole drilled down to 750 m in the Wonju granite region, where multidisciplinary research was conducted. The deformation moduli obtained from the deep borehole loading tests were classified into the initial shear modulus and the deformation modulus derived from unloading/ reloading shear moduli. The initial shear moduli ranged from 9,249 to 13,895 MPa, the unloading/reloading shear moduli ranged from 8,083 to 15,120 MPa, and the calculated deformation moduli ranged from 20,207 to 37,800 MPa.

Keywords

Pressuremeter test

High-level radioactive waste

Deep depth

Deformation modulus

High-pressure dilatometer

고준위방사성폐기물 처분시설은 최소 300 m 이하의 지하 심부 암반에 건설될 것으로 예상된다. 지하 암반의 변형은 고준위방사성폐기물 처분시설의 안정성뿐 아니라 일반적인 지반구조물의 안정성에도 큰 영향을 준다. 따라서 고준위방사성폐기물 처분시설의 경우, 처분심도에서 암반 변형 특성을 파악하는 것은 중요하다. 그러나 지금까지 국내에서는 적용 대상이나 장비 등의 한계로 천부에서 변형을 측정하거나 추정식을 통하여 예측하여 왔다. 이에 본 연구에서는 고압 팽창계를 기반으로 한 대심도 공내재하시험장치를 활용하여 심도 449 m까지 시험을 수행하여 전단계수와 변형계수를 획득하였다. 시험은 다학제적 연구가 수행되었던 원주 화강암 지역에 시추된 750 m 급 시추공에서 수행되었다. 대심도 공내재하시험으로부터 획득한 변형계수는 초기 전단계수와 제하/재하 전단계수에 의한 변형계수로 구분하였다. 획득한 초기 전단계수의 범위는 9.249~13,895 MPa를, 제하/재하 전단계수의 범위는 8.083~15,120 MPa의 값을 보이며, 이들로부터 산정한 변형계수는 20,207~37,800 MPa값을 보였다.

키워드

공내재하시험

고준위방사성폐기물

대심도

변형계수

고압 팽창계

References

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Lee, C.M., 1997, A Study on the Estimation of Deformation and Reload Modulus by Pressuremeter Test, Yonsei University, Master's thesis, 64p.

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Information

Publisher :Korean Society for Rock Mechanics and Rock Engineering
Publisher(Ko) :한국암반공학회
Journal Title :Tunnel and Underground Space
Journal Title(Ko) :터널과 지하공간
Volume : 34
No :6
Pages :636-649
Received Date : 2024-12-02
Revised Date : 2024-12-18
Accepted Date : 2024-12-23
DOI :https://doi.org/10.7474/TUS.2024.34.6.636

Tunnel and Underground SpaceISSN:1225-1275(Print) 2287-1748(Online)한국암반공학회

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