Estimation of Mechanical Representative Elementary Volume and Deformability for Cretaceous Granitic Rock Mass: A Case Study of the Gyeongsang Basin, Korea

Jeong-Gi Um; Seongjin Ryu

doi:10.9720/kseg.2022.1.059

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2022 Vol.32, Issue 1 Preview Page Next Page

Research Article

Estimation of Mechanical Representative Elementary Volume and Deformability for Cretaceous Granitic Rock Mass: A Case Study of the Gyeongsang Basin, Korea 경상분지 백악기 화강암 암반에 대한 역학적 REV 및 변형특성 추정사례

31 March 2022. pp. 59-72

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Abstract

This study employed a 3-D numerical analysis based on the distinct element method to estimate the strength and deformability of a Cretaceous biotite granitic rock mass at Gijang, Busan, Korea. A workflow was proposed to evaluate the scale effect and the representative elementary volume (REV) of mechanical properties for fractured rock masses. Directional strength and deformability parameters such as block strength, deformation modulus, shear modulus, and bulk modulus were estimated for a discrete fracture network (DFN) in a cubic block the size of the REV. The size of the mechanical REV for fractured rock masses in the study area was determined to be a 15 m cube. The mean block strength and mean deformation modulus of the DFN cube block were found to be 52.8% and 57.7% of the intact rock’s strength and Young’s modulus, respectively. A constitutive model was derived for the study area that describes the linear-elastic and orthotropic mechanical behavior of the rock mass. The model is expected to help evaluate the stability of tunnels and underground spaces through equivalent continuum analysis.

Keywords

fractured rock mass

discrete fracture network

deformability

3-D distinct element method

constitutive model

본 연구는 부산 기장지역의 백악기 흑운모 화강암에 대하여 삼차원 개별체 수치해석 기반의 응력-변형 해석을 수행하고 절리성 암반의 강도 및 변형특성을 평가하였다. 절리성 암반의 역학적 특성에 대한 규모효과 및 REV를 규명하기 위한 워크플로우가 제시되었으며 연구지역에서 결정된 REV(representative elementary volume) 크기의 DFN(discrete fracture network) 큐브 블록에 대한 블록강도, 변형계수, 전단탄성계수, 체적탄성계수 등의 강도 및 변형 파라미터가 산정되었다. 연구지역의 역학적 REV 크기는 15 m 큐브로 평가되었으며 DFN 큐브 블록의 평균 블록강도 및 평균 변형계수는 각각 신선암의 52.8% 및 57.7%로 추정되었다. 연구지역의 절리성 암반은 역학적으로 뚜렷한 직교이방성을 나타내는 것으로 평가되었으며 삼차원 수치해석을 통하여 산정된 변형 파라미터를 이용하여 선형-탄성의 직교이방성 구성모델이 도출되었다. 연구지역에 대한 직교이방성 구성모델은 등가의 연속체 해석을 통한 터널 및 지하공간의 안정성 평가에 활용될 수 있다.

키워드

절리성 암반

불연속절리망

변형특성

삼차원 개별요소법

구성모델

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Information

Publisher :Korean Society of Engineering Geology
Publisher(Ko) :대한지질공학회
Journal Title :The Journal of Engineering Geology
Journal Title(Ko) :지질공학
Volume : 32
No :1
Pages :59-72
Received Date : 2022-03-08
Revised Date : 2022-03-25
Accepted Date : 2022-03-27
DOI :https://doi.org/10.9720/kseg.2022.1.059

The Journal of Engineering Geology ISSN:1226-5268(Print) 2287-7169(Online) 지질공학

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