한국지반공학회논문집 (Journal of the Korean Geotechnical Society)

한국지반공학회 (Korean Geotechnical Society)
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실규모 현장시험을 통한 부착형 암반앵커의 인발저항력 평가

Uplift Capacity Estimation of Bond-type Rock Anchors Based on Full Scale Field Tests

  • 김대홍 (한국전력공사 전력연구원) ;
  • 오기대 (한국전력공사 전력연구원)
  • 투고 : 2008.08.07
  • 심사 : 2009.10.12
  • 발행 : 2009.10.31
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초록

본 논문에서는 옥천 및 창녕지역에서 총 24회 수행한 암반앵커 현장인발시험의 결과를 나타내었다. 시험앵커의 정착깊이는 1~6m로 서로다른 암반내에 설치하였다. 앵커의 대부분은 고강도 이형철근인 SD40-D51mm를 사용함으로써 다른 파괴가 일어나기 전에 암반파괴가 먼저 일어나도록 유도하여 암반의 인발저항력을 파악하고자 하였으며, 일부에서는 SD40-D32mm앵커를 설치하여 앵커의 파괴도 아울러 살펴보았다. 많은 시험에서 파괴는 항복에 이르는 극한하중까지 관찰할 수 있었으며, 암반파괴형상은 암반이 들어올려지면서 방사상으로 균열이 발달하는 형태를 나타내었다. 또한 시멘트그라우트와 텐던사이의 부착강도를 평가하고자 방식쉬이스가 설치된 앵커에 대해 실내실험을 실시하였다. 실험결과 텐던-그라우트 사이의 부착강도는 그라우트 일축압축강도의 18~25%로 나타났으며, 방식쉬이스에 의한 부착력 감소는 무시할 수 있을 정도로 작게 나타났다.

This paper presents the results of full-scale uplift load tests performed on 24 passive anchors grouted to various lengths at Okchun and Changnyong site. Rock anchors were installed over a wide range of rock types and qualities with a fixed anchored depth of 1~6 m. The majority of installations used D51 mm high grade steel rebar to induce rock failure prior to rod failure. However, a few installations included the use of D32 mm rebar at relatively deeper anchored depth so as to induce rod failure. In many tests, rock failure was reached and the ultimate loads were recorded along with observations of the shape and extent of the failure surface. In addition to field tests, laboratory pullout tests were conducted to determine bond strength and bond stress-shear slip relation at the tendon/grout interface when a corrosion protection sheath is installed in the cement-based grout. The test results show that the ultimate tendon-grout bond strength is measured from 18~25% of unconfined compressive strength of grout. One of the important results from these tests is that the measured strains along the corrosion protection sheath were so small that practically the reduction of bond strength by the presence of sheath would be negligible.

키워드

참고문헌

  1. 김대홍, 이대수, 천병식, 김병홍 (2006), "암반에 근입된 부착형 앵커의 거동특성 (I) - 태안지역 편마암", 한국지반공학회 논문집, 제22권 제12호, pp.45-55
  2. Benmokrane, B., Chennouf, A. and Mitri, H. S. (1995), "Laboratory Evaluation of Cement-Based Grouts and Grouted Rock Anchors", Int. J. Rock Mech. Min. Sci. & Geomech. Abstr., Vol.32, No.7, pp.633-642 https://doi.org/10.1016/0148-9062(95)00021-8
  3. Bruce, D. A. (1993), The Stabilization of Concrete Dams by Post- Tensioned Rock Anchorages: The State of American Practice, Geotech. Spec. Publ. No. 35, Geotech. Practice in Dam Rehabilitation, ASCE, New York, pp.320-332
  4. British Standards Institution (1989), British Standard Code of Practice for Ground Anchorages, BS8081, London, England, pp. 115-125
  5. Coates, D. F. and Yu, Y. S. (1970), "Three Dimensional Stress Distributions Around a Cylindrical Hole and Anchor", Proc. 2nd Int. Conf. on Rock Mechanics, Belgrade, pp.175-182
  6. Coates, D. F. and Yu, Y. S. (1971), Rock Anchor Design Mechanics, Dept. of Energy Mines and Resource, Research Report No. R233, pp.78-85
  7. Farmer, I. W. (1975), "Stress Distribution along a Resin Grouted Anchor", Int. J. Rock Mech. & Geomech. Abster., Vol.12, pp. 347-351 https://doi.org/10.1016/0148-9062(75)90168-0
  8. Hinks, J. I., Burton, I. W., Peacock, A. R. and Gosschalk, E. M. (1990), "Post-Tensioning Mullardoch Dam in Scotland", Water Power and Dam Constr., Nov., pp.12-15
  9. Hobst, L. and Zajic, J. (1977), Anchoring in Rock, Development in Geotechnical Engineering, Vol.13, Elsevier Scient. Publ., Amsterdam, pp.25-50
  10. Ismael, N. F., Radhakrishna, H. S. and Klym, T. W. (1980), "Uplift Capacity of Anchors in Transmission Tower Design", IEEE Transactions on Power Apparatus and System, Vol.PAS-98, No.5, pp.1653-1658
  11. Ismael, N. F. (1982), "Design of Shallow Rock-Anchored Foundations", Canadian Geotechnical Journal, Vol.19, No.2, pp.469-471 https://doi.org/10.1139/t82-050
  12. Kim, D. H. and Lee, S. R. (2005), "Uplift Capacity of Fixed Shallow Anchors subjected to Vertical Loading in Rock", International Journal of Offshore and Polar Engineering, Vol.15, No.4, pp.312-320
  13. Kulhawy, F. H. (1985), "Uplift Behavior of Shallow Anchors", Proc. of a Session sponsored by the Geotech. Eng. Division of ASCE, pp.238-245
  14. Littlejohn, G. S. and Bruce, D. A. (1977), "Rock Anchors-Design and Quality Control", Proc. 16th Symp. on Rock Mechanics, University of Minnesota, pp.77-88
  15. Littlejohn, G. S. (1970), Soil Anchors, I.C.E. Conference on Ground Engineering, London, pp.115-120
  16. Nicholson, P. J., Uranowski, D. D. and Wycliffe-Jones, P. T. (1982), Permanent Ground Anchors-Nicholson Design Criteria, Fed. Highwy. Adm. Office of Research and Development, U.S. Dept. Transp., Report No. FHWA/RD-81/151, Washington, D.C., pp.1-25
  17. Saliman, R. and Schaefer, R. (1968), "Anchored Footings for Transmission Towers", ASCE Annual Meeting and National Meeting on Structural Engineering, Pittsburge, PA, Sept. 3~Oct. 4, Preprint 753, pp.15-38
  18. U. S. Army Corps of Engineers (1994), Engineering and Design Rock Foundations, EM 1110-1-2908, Nov. 30, pp.69-73
  19. Xanthakos, P. P. (1991), Ground Anchors and Anchored Structures, John Wiley & Sons, Inc. pp.130-139