All Issue

2020 Vol.30, Issue 3 Preview Page

Research Article

The Change of Pillar Strength due to Joint Dip Angles, Total Trace Length and Width-to-Height ratio of a Pillar

절리면의 방향, 절리선 길이 및 광주 형상비가 광주 강도에 미치는 영향 분석

Ji-won Choi1
,
Yong-Ki Lee2
,
Jae-Joon Song3*
최 지원1
,
이 용기2
,
송 재준3*
1Master’s Course, Department of Energy Systems Engineering, Seoul National University
2Ph.D Candidate, Department of Energy Systems Engineering, Seoul National University
3Professor, Department of Energy Systems Engineering, Seoul National University
1서울대학교 에너지시스템공학부 석사과정
2서울대학교 에너지시스템공학부 박사과정
3서울대학교 에너지시스템공학부 교수
* Corresponding Author
30 June 2020. pp. 226-241
PDF XML Citation
Abstract

The stability of underground mine cavity is closely related with pillar strength. The vulnerability of pillars can be judged and reinforced if the pillar strength is known. The pillar strength is affected by characteristics of discontinuities and shape of a pillar. The change of pillar strength due to a discontinuity passing through the center of a pillar, width-to-height ratio of a pillar and small joints existing within a pillar was analyzed using PFC 3D. The result showed that the pillar strength is influenced by dip angle of a discontinuity and it increases as width-to-height ratio of a pillar increases. The pillar strength decreases as the number of contained joints increases. The relationship between total trace length observable from the pillar surface and the pillar strength was regressed with exponential function. The correlation coefficient of the regression was high enough so that pillar strength can be predicted using total trace length if a joint set exists in a pillar. Lastly, the method to estimate the strength of a pillar that includes two joint sets was proposed if the joint dip angles are 60°, 30°. The method also need total trace lengths of two joint sets.

Keywords
Pillar strength
Discontinuity
Width-to-height ratio
Contained joint
Total trace length

지하 광산 공동의 안전성은 광주의 강도와 밀접한 관계가 있다. 광주의 강도를 알고 있다면 광주의 위험성을 판단할 수 있고 그에 따른 적절한 조치를 취할 수 있다. 광주의 강도는 광주 내에 존재하는 불연속면의 특성과 광주의 형상에 영향을 받는다. 본 연구에서는 광주를 관통하는 불연속면과 광주의 종횡비, 광주 내부에 존재하는 소규모의 내포 절리에 따른 강도 변화를 PFC 3D를 이용하여 분석하였다. 그 결과, 광주의 강도는 불연속면의 경사각에 영향을 받으며, 광주의 폭이 넓어질수록 강도가 증가하고 내포 절리의 수가 증가할수록 강도가 감소함을 확인하였다. 내포 절리로 인해 광주 표면에 나타나는 절리선 길이의 총합과 광주 강도와의 관계를 지수 함수로 회귀한 결과, 두 인자 사이의 높은 상관계수를 얻었다. 따라서 하나의 절리군이 존재할 때, 지수 함수식을 통해 절리선 길이의 총합으로부터 광주의 강도를 예측할 수 있다. 마지막으로 경사각이 60°, 30°인 두 절리군이 존재할 때 절리선 길이의 총합으로부터 광주 강도를 추정할 수 있는 식을 제시하였다.

키워드
광주 강도
불연속면
광주 종횡비
내포 절리
절리선 길이의 총합
References
1
Castro-Filgueira, U., Alejano, L.R., Arzua, J. and Mas Ivars, D., 2017, Sensitivity Analysis of the Micro-Parameters Used in a PFC Analysis Towards the Mechanical Properties of Rocks, Procedia Engineering, 191, 488-495.
10.1016/j.proeng.2017.05.208
2
Cundall, P.A. , Pierce, M.E. and Mas Ivars D., 2008, Quantifying the Size Effect of Rock Mass Strength, Southern Hemishere International Rock Mechanics Symposium.
10.36487/ACG_repo/808_31
3
Esterhuizen, G.S., 2006, An Evaluation of the Strength of Slender Pillars, Transaction Society for Mining, Metallurgy, and Exploration 320: Littleton, CO, 69-76.
4
Itasca Consulting Group Inc, 2008, PFC3D manual, version 6.0, Minneapolis.
5
Jessu, K.V. and Spearing, A.J.S., 2019, Performance of Inclined Pillars with a Major Idscontinuity, International Journal of Mining Science and Technology, 29, 437-443.
10.1016/j.ijmst.2018.09.006
6
Kim, D.B., Lee, S.G. and Lee, C.H., 2001, The Engineering Properties of Shear Strength of Rock Joints in Korea, Journal of the Korean Geotechnical Society, 17(4), 301-315.
7
Kim, J.W., Kim, M.S., Kim, P.G., Nor, S.J., Park, C., Jo, Y.D. and Park, S.G., 2012, The Mechanical Properties of Limestones Distributed in Jecheon, Tunnel and Underground Space, 22(5), 354-364.
10.7474/TUS.2012.22.5.354
8
Koo, C.M., Jeon, S.W. and Lee, I.W., 2008, Underground Mine design and Stability Analysis at a Limestone Mine, Tunnel and Underground Space, 18(4), 243-251.
9
KORES, 2017, 2016 Statistics of Mine Accidents, KORES report, 1-44.
10
Lee, S.E. and Jang, Y.H., 2010, Stability Assesment of the Slope at the Disposal Site of Waste Rock in Limestone Mine, Tunnel and Underground Space, 20(6), 475-490.
11
Lee, S.W. and Song, J.J., 2006, A study on the Change of Uniaxial Compressive Strength and Young's Modulus According to the Specimen Size of Intact Material, Tunnelling Technology, 8(3), 205-217.
12
Martin, C.D. and Maybee, W.G., 2000, The Strength of Hard-rock Pillars, International Journal of Rock Mechanics & Mining Sciences, 37, 1239-1246.
10.1016/S1365-1609(00)00032-0
13
Mas, D., Pierce, M., DeGagne, D. and Darcel, C.,2008, Anisotropy and Scale Dependency in Jointed Rock-mass Strength -A Synthetic Rock Mass Study, Proceedings of the 1st International FLAC/DEM Symposium on Numerical Modeling, 231-239.
14
NIOSH, 2011, Pillar and Roof Span Design for Underground Stone Mines, 1-64, Pittsburgh, PA･Spokane, WA, the United States.
15
Park, B.N. and Min, K.B., 2017, Two- and Three-Dimensional Bonded-particle Discrete Element Modeling of Mechanical Behavior of Transversely Isotropic Rock, Department of Energy Systems Engineering, Seoul National University.
16
Park, E.S., Martin, C.D. and Christiansson, R., 2004, Simulation of the Mechanical Behavior of Discontinuous Rock Masses Using a Bonded-particle Model, The 6th North America Rock Mechanics Symposyum(NARMS)
10.1201/b17007-14
17
Potyondy, D.O. and Cundall, P.A., 2004, A Bonded-particle Model for Rock, International Journal of Rock Mechanics & Mining Sciences, 41, 1329-1364.
10.1016/j.ijrmms.2004.09.011
18
Shin, H.S., Sunwoo, C., Han, K.C. and Park, Y.J., 1996, Study on the stability of tunnel and rock mass classification in Danyang limestone quarry, Tunnel and Underground Space, 6, 131-143.
19
Vallejos, J.A., Salinas, J.M., Delonca, A. and Mas Ivars, D.,2016, Calibration and Verification of Two Bonded-Particle Models for Simulation of Intact Rock Behavior, International Journal of Geomechanics 17:06016030.
10.1061/(ASCE)GM.1943-5622.0000773
20
Wanrui, H., Tao, W., Kwok, C.Y. and Kang, D., 2016, The Effect of Smooth-joint Parameters on the Mechanical Behavior of Jointed Rock, 50th US Rock Mechanics/Geomechanics Symposium, Houston, Texas, 41.
21
Yang, B., Jiao, Y. and Lei, S., 2006, A Study on the Effects of Microparameters on Macroproperties for Specimens Created by Bonded Particles, Engineering Computations, 23(6), 607-631.
10.1108/02644400610680333
22
Zhang, Y., Stead, D. and Elmo, D., 2015, Charaterization of Strength and Damage of Hard Rock Pillars Using Asynthetic Rock Mass Method, Computers and Geotechnics, 65, 56-72.
10.1016/j.compgeo.2014.12.002
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 : 30
  • No :3
  • Pages :226-241
  • Received Date : 2020-06-08
  • Revised Date : 2020-06-24
  • Accepted Date : 2020-06-25
  • DOI :https://doi.org/10.7474/TUS.2020.30.3.226
Journal Informaiton Tunnel and Underground Space Tunnel and Underground Space
Online Submission
Archives
: Vol.27, 2017 ~
  • NRF
  • KOFST
  • KISTI Current Status
  • KISTI Cited-by
  • crosscheck
  • orcid
  • open access
  • ccl
Journal Informaiton Journal Informaiton - close