A Study on Applicability of Equivalent Continuum Flow Model in DFN Media

Dahye Lee; Jeong-Gi Um

doi:10.7474/TUS.2017.27.5.303

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2017 Vol.27, Issue 5 Preview Page Next Page

Research Article

A Study on Applicability of Equivalent Continuum Flow Model in DFN Media DFN 매질에 대한 등가연속체 유동모델의 적용 가능성 평가에 관한 연구

1 October 2017. pp. 303-311

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Abstract

The correlation analysis between the results obtained from DFN flow model and equivalent continuum flow model were conducted on total of 72 DFN blocks having various fracture geometry and domain size. A strong linear relation seems to exist between the two approaches under condition that normalized relative error for continuum behavior (ER) is less than 0.2, and the results from both methods are found to almost identical. To explore the field applicability of equivalent continuum flow model in DFN media, a total of 48 numerical schemes related to inflow of underground circular openings were implemented under various DFN configurations. The equivalent continuum flow model in DFN media with a constant hydraulic aperture was evaluated as valid. However, as the anisotropy increases due to variation of the hydraulic aperture, the results are likely to be overestimated compare to the DFN flow model.

Keywords

Discrete fracture network

Equivalent continuum flow model

DFN flow model

Numerical experiments

본 연구는 다양한 기하학적 속성을 갖는 총 72개의 DFN 블록에 대하여 DFN 유동모델과 등가의 수리상수를 사용한 연속체 모델을 각각 적용하여 두 결과 간의 상관성을 분석하였다. DFN을 연속체로 가정한 이론적 블록수리전도도와 DFN 유동모델로 산정한 블록수리전도도 사이의 상대오차(ER)가 0.2 이하인 DFN 조건에서 두 접근법 사이에 강한 선형 관계를 이루며 두 결과가 거의 일치하는 것으로 평가되었다. DFN 매질에 대한 연속체 유동해석의 현장적용 가능성을 검토하기 위하여 다양한 DFN 조건을 갖는 지중 원형공동에서의 지하수 유입에 대한 모의 수치실험이 총 48회 수행되었다. 일정한 수리간극의 DFN 매질에 대한 등가연속체 유동모델은 유효한 것으로 평가되었지만 수리간극 변화로 인하여 이방성이 증대되면 DFN 유동모델에 의한 결과에 비하여 과대평가될 가능성이 높다.

키워드

불연속절리망

등가연속체 유동모델

DFN 유동모델

수치실험

References

Han J., 2016, Analysis of hydraulic characteristics of fractured rock masses through 2-D DFN fluid flow modeling, Master thesis, Pukyong National University, 104p.

Han, J. and J. Um, 2015, Characteristics of block hydraulic conductivity of 2-D DFN system according to block size and fracture geometry, Tunnel & Underground Space (J. of Korean Society for Rock Mech.), 25, 450-461.

Han, J. and J. Um, 2016, Effect of joint aperture variation on hydraulic behavior of the 2-D DFN system, Tunnel & Underground Space (J. of Korean Society for Rock Mech.), 26, 283-292.

Long, J.C.S., J.S. Remer, C.R. Wilson and P.A. Witherspoon, 1982, Porous Media Equivalents for networks of Discontinuous fractures, Water Resour. Res. 18.3, 645-658.

Oda, M., 1985, Permeability tensor for discontinuous rock mass, Géotechnique, 35, 483-495.

Rocha, M. and F. Franciss, 1977, Determination of permeability in anisotrophic rock masses from integral samples, Structural and Geotechnical Mechanics, edited by W. J. Hall, Prentice-Hall, New York, 178-202.

Snow, D. T., 1965, A parallel plate model of fractured permeable media, Ph.D. dissertation, University of California, Berkeley, 331p.

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 : 27
No :5
Pages :303-311
Received Date : 2017-10-09
Revised Date : 2017-10-25
Accepted Date : 2017-10-25
DOI :https://doi.org/10.7474/TUS.2017.27.5.303

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

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