Evaluation of Brittle Failure Characteristics using the Finite Method and Discrete Element Method

Dae-Sung Cheon; Seokwon Jeon; Jang-Baek Lee

doi:10.32390/ksmer.2019.56.6.582

All Issue

2019 Vol.56, Issue 6 Preview Page Next Page

Research Paper

Evaluation of Brittle Failure Characteristics using the Finite Method and Discrete Element Method 유한차분법과 개별요소법을 활용한 취성파괴 특성 평가

31 December 2019. pp. 582-595

PDF XML

Abstract

The relationship between brittle failure and applied stress conditions using finite difference method and discrete element method was evaluated. The characteristics of brittle failure were classified into the initiation stress, extent and depth. FLAC^3D and PFC^3D were adopted as FDM and DEM, respectively. Numerical experiments were performed under triaxial stress conditions and compared with the previous experiments. The CWFS model in FDM could simulate the V-shaped failure well. The magnitude of the differential stress perpendicular to the opening axis and the extent/depth of failure were linearly proportional. Spalling could be simulated as particle separating in DEM. The crack initiation stress in DEM can be a good indicator of when failure starts in the experiment or field. PFC^3D can reflect the effects of 3D stress conditions, but there were difficulties in distinguishing the depth and extent of failure. Therefore, it is necessary to select appropriate numerical methods in assessing brittle failure.

Keywords

brittle failure

FDM

DEM

CWFS model

높은 현지응력이 작용할 때 발생 가능한 취성파괴에 대하여 유한차분법과 개별요소법을 이용하여 재하된 응력사이와의 관계를 평가하였다. 취성파괴는 파괴개시시점, 파괴범위와 파괴심도 등으로 구분하였다. 유한차분법으로 FLAC^3D, 개별요소법으로 PFC^3D를 사용하였다. 삼축응력조건에서 취성파괴 수치실험을 수행하여 기존 모형실험결과와 비교하였다. 유한차분법에서 사용된 CWFS 모델이 v-형태의 취성파괴를 잘 모사할 수 있음을 알 수 있었다. 공동 축에 수직한 축차응력의 크기와 파괴범위/파괴심도가 선형 비례함을 보였다. 개별요소법의 경우 스폴링를 입자탈락으로 모사할 수 있었으며, 수치실험의 균열개시응력이 모형실험이나 현장관찰의 파괴개시시점에 대한 좋은 지시자가 될 수 있음을 확인하였다. PFC^3D는 FLAC^3D와 달리 3차원 응력조건의 영향을 반영할 수 있으나, 취성파괴의 정도를 표현하는 파괴심도와 파괴범위를 구별하는 데 어려움이 존재하였다. 따라서 취성파괴를 예측 또는 평가하는 데 있어 해석목적에 맞는 수치해석방법의 선택이 필요한 것으로 나타났다.

키워드

취성파괴

유한차분법

개별요소법

CWFS 모델

References

Aglawe, J.P., 1999. Unstable and violent failure around underground openings in highly stressed ground. Ph.D. Dissertation, Queen's University at Kingdom, Canada.

Andersson, J.C., Martin, C.D., and Stille, H., 2009. The Äspö pillar stability experiment: Part II-Rock mass response to coupled excavation-induced and thermal-induced stresses. Int. J. Rock Mech. & Min. Sci., 46(5), 879-895.

10.1016/j.ijrmms.2009.03.002

Andreev, G.E., 1995. Brittle failure of rock materials: test results and constitutive models. A.A. Balkema, Netherlands, 454p.

Aubertin, M., Gill, D.E., and Simon, R, 1994. On the use of the brittleness index modified (BIM) to estimate the post-peak behavior of rocks. American Rock Mechanics Association, 945-952.

Castro, L.A.M., 1996. Analysis of stress-induced damage initiation around deep openings excavated in a moderately jointed brittle rock mass. Ph.D. Dissertation, University of Toronto, Canada.

Cheon, D.S., Jeon, S., Park, C., and Ryu, C., 2006. An experimental study on the brittle failure under true triaxial conditions. Tunn. Undergr. Sp., 21, 448-449.

10.1016/j.tust.2005.12.087

Cheon, D.S., Park, C., Jeon, S.-W., and Jung, Y.-B., 2007. Damage-controlled test to determine the input parameters for CWFS model and its application to simulation of brittle failure. J. Korean Tunn. Undergr. Sp. Assoc., 9(3), 263-273.

Diederichs, M.S., 1999. Instability of hard rock masses: the role of tensile damage and relaxation. Ph.D. Dissertation, University of Waterloo, Canada.

Feng, R., Zhang, Y., Rezagholilou, A., Roshan, H., and Sarmadivaleh, M., 2019. Brittleness index: from conventional to hydraulic fracturing energy model. Rock Mech. Rock Eng,

10.1007/s00603-019-01942-1.

Hajiabdolmajid, v., Kaiser, P.K., and Martin, C.D., 2002. Modeling brittle failure of rock. Int. J. Rock Mech Min, 39, 731-741.

10.1016/S1365-1609(02)00051-5

Hoek, E., Kaiser, P.K., and Bawden, W.F., 1995. Support of underground excavations in hard rock. A.A Balkema, Rotterdam, 215p.

Jang, H.S., Choe, M.M., Bae, D.S., Kim, G.Y., and Jang, B.A., 2015. Prediction of brittle failure within Mesozoic granite of the daejeon region. J. Eng. Geol., 25(3), 357-368.

10.9720/kseg.2015.3.357

Jung, Y.S., 2005. Numerical study for mechanical behavior of cement mortar using 3-dimensional particle flow code, MS Thesis, Seoul National University, Korea.

Kaiser, P.K., Diederichs, M.S., Martin, C.D., Sharp, J., Steiner, W., Underground works in hard rock tunneling and mining. Keynote lecture at GeoEng2000, Melbourne, Australia, Technomic Publishing Co. 2000, 1. 841-926.

Lee, S.M., Park, B.S., and Lee, S.W., 2004. Analysis of rockbursts that have occurred in a waterway tunnel in Korea. Int. J. Mech & Min. Sci., 41(3B), 24p.

10.1016/j.ijrmms.2004.03.157

Martin, C.D. and Chandler, N.A., 1994. The progressive fracture of Lac du Bonnet granite. Int. J. Rock Mech. & Min. Sci., 31, 643-659.

10.1016/0148-9062(94)90005-1

Martin, C.D., 2001. Rock stability considerations for siting and construction a KBS-3 repository, SKB Technical Report.

Martin, C.D., 2014. The impact of brittle behaviour of rocks on tunnel excavation design. In: Proceedings of EUROCK2014, vigo, 51-62.

10.1201/b16955-7

Martin, C.D., Kaiser, P.K., and McCreath, D.R., 1999. Hoek- Brown parameters for predicting the depth of brittle failure around tunnels. Canadian Geotech. J., 36, 136-151.

10.1139/t98-072

Ortlepp, W.D., 1997. Rock fracture and rockbursts-an illustrative study. Monograph Series, South African Institute of Mining and Metallurgy, Johannesburg.

Information

Publisher :The Korean Society of Mineral and Energy Resources Engineers
Publisher(Ko) :한국자원공학회
Journal Title :Journal of the Korean Society of Mineral and Energy Resources Engineers
Journal Title(Ko) :한국자원공학회지
Volume : 56
No :6
Pages :582-595
Received Date : 2019-10-02
Revised Date : 2019-12-09
Accepted Date : 2019-12-20
DOI :https://doi.org/10.32390/ksmer.2019.56.6.582

Journal of the Korean Society of Mineral and Energy Resources EngineersISSN:2288-0291(Print) 2288-2790(Online)한국자원공학회

All Issue