초록

기존의 액상화 평가법은 대부분 미국, 일본, 그리고 유럽과 같이 지진 발생빈도가 높고 그로 인한 액상화 피해가 빈번한 국가에서 주도적으로 연구되어왔다. 이런 지역적 특성을 토대로 개발된 액상화 평가방법들은 높은 지진규모(M=7.5)에 바탕을 두고 있다. 국내의 경우, 1997년 실제적인 내진 연구가 시작된 이래 액상화 평가의 구체적 규정은 항만시설의 내진설계 표준서(1999)에 언급된 바 있으나 이는 문헌연구를 통해 제시된 것으로 실제적이지 못하다. 그러므로, 국내 적합한 설계기준을 작성하기 위해서는 지진피해자료의 부족을 국내 지반을 대상으로 한 동적실내시험을 통하는 것이 바람직하며, 일반적인 정현하중 진동시험 보다 실제 지진하중 재하 시험이 훨씬 효과적일 수 있다. 본 연구에서는 실제 지진파 고유의 특성을 적용한 진동삼축 시험을 통하여 상대밀도와 세립분함유량의 변화에 따른 액상화 저항강도를 산정하였다. 실험결과를 국내의 대표적인 항만지역의 지진응답 해석 결과와 비교 분석하고 중진지역에 적합한 액상화 평가의 생략기준을 제시하였다. 또한 실제 지진하중 삼축실험 결과를 이용하여 국내 여건에 적합한 지진규모 보정계수를 제안하였다.

Abstract

Conventional methods for the assessment of liquefaction potential were primarily for areas of severe earthquake zones (M=7.5) such as North America and Japan. Detailed earthquake related researches in Korea started in 1997, including development of the seismic design standards for port and harbour structures, which was later completed in 1999. Because most contents in the guidelines were quoted through literature reviews from North America and Japan, which are located in strong earthquake region, those are not proper in Korea, a moderate earthquake region. This requires further improvement of the present guidelines. Considering earthquake hazard data in Korea, use of laboratory tests based on irregular earthquake motion appears to be effective to reflect the dynamic characteristics of soil more realistically than those using simplified regular loading. In this study, cyclic triaxial tests using irregular earthquake motions are performed with different earthquake magnitudes, relative densities, and fines contents. Assessment of liquefaction potential in moderate earthquake regions is discussed based on various laboratory test results. Effects of these components on dynamic behavior of soils are discussed as well. From the test results, screening limits and magnitude scaling factors to determine the soil liquefaction resistance strength in seismic design were re-investigated and proposed using normalized maximum stress ratios under real irregular earthquake motions.

주제어

#Assessment of liquefaction potential   #Irregular earthquake motions   #Liquefaction resistance ratio   #Magnitude scaling factors   #Screening limits   #Triaxial tests  

참고문헌 (26)

1. Abrahamson, N. and Silva, W. (1996), Empirical ground motion models, draft Report. Brookhaven National Laboratory 
2. Amini, F. and Qi, G. Z. (2000), 'Liquefaction testing of stratified silty sands', J. Geotech. and Egoenvir. Engrg., ASCE, Vol.126, No.3, pp.208-217 
3. ASTM D 4254. (1991), 'Standard test methods for minimum index density and unit weight of soils and calculation of relative density', American Society of Testing and Materials, West Conshohocken, Pennsylvania, USA 
4. ASTM D 4253. (1993), 'Standard test methods for maximum index density and unit weight of soils using a vibratory table', American Society ofTesting and Materials, West Conshohocken, Pennsylvania, USA 
5. Liu, A H. Stewart, J. P., Abrahamson, N. A, and Moriwaki, Y. (2001), 'Equivalent number of uniform stress cycles for soil liquefaction analysis', J. Geotech. Engrg., ASCE, Vol.127, No.12, pp.1017-1026 
6. Polito, C. P. and Martin II, J. R. (2001), 'Effects of nonplastic fines on the liquefaction resistance of sands', J Geotech. and Geoenviron Engng. Vol.127, No.5, pp.408-415 
7. Seed, H. B., Idriss, I. M., Makdisi, F., and Banerjee, N. (1975), Representation of Irregular Stress Time Histories by Equivalent Uniform Stress Series in Liquefaction Analysis. Report No. EERC 7529, UCB 
8. Tsuchida, H. (1970), 'Prediction and remedial measures against liquefaction of sandy soil', Annual Seminar of Port and Harbor Research Institute: Vol.3, pp.1-33 (in Japanese) 
9. Vaid Y. P. and Sivathayalan S. (1996), 'Static and cyclic lique-faction potential of Fraser Delta sand in simple shear and triaxial tests', Canadian Geotechnical Journal, Vol.33, pp.281-289 
10. Mulilis, J. P. (1975), The effects of method of sample preparation on the cyclic stress strain behavior of sands. EERC Report 7518, College of Engineering, University of California, Berkeley, July 
11. Idriss, I. M. and Sun, J. I. (1992), Users Manual for SHAKE91, Department of Civil and Environmental Engineering, Univ. California, Davis 
12. Dobry, R. (1991), 'Soil properties and earthquake ground response', Proceedings of the 10th European Conference on Soil Mechanics and Foundation Engineering, Florence, Italy, Vol.4 
13. Idriss, I. M. (1999), 'An update to the Seedldriss simplified procedure for evaluating liquefaction potential', Presentation notes, Workshop new approaches to liquefaction analysis, Transportation Research Board, Washington, D. C. 
14. Earthquake engineering society of Korea (1999), Seismic design standard for port and harbour structures, Ministry of maritime affairs and fisheries (in Korean) 
15. Seed, R. B., Cetin, K. O., Mossw, R. E. S., Kammerer, A. M., Wu, J., Pestana, J. M., Riemer, M. F., Sancio, R. B., Bray, J. D., Kayen, R. E., and Faris, A. (2003), Recent advances in soil liquefaction engineering: A unified and consistent framework. Report No. EERC 2003-06, UCB 
16. Kim, S. I. (1998), 'Assessment and remediation for liquefaction in Korea', Proc.. KGS Fall 1998 Nat. Conf., pp.3-30 
17. Seed, H. B. and Idriss, I. M. (1982), Ground motions and soil liquefaction during earthquakes. Earthquake Engrg. Res. Inst., Oaklanc, California 
18. Youd, T. L., and Idriss, I. M., eds. (1997), Proc., NCEER Workshop on Evaluation of Liquefaction Resistance of Soils, Nat. Ctr. for Earthquake Engrg. Res., State Univ. of New York at Buffalo 
19. Schnabel, P. B., Lysmer, J., and Seed, H. B. (1972), A computer program for earthquake response analysis of horizontally layered sites. Report no. EERC 7212, Earthquake Engineering Research Center, Univ. California, Berkeley 
20. Andrus, R. D. and Stokoe, K. H., Il. (1997), 'Liquefaction resistance based on shear wave velocity', Proc., NCEER Workshop on Evaluation of Liquefaction Resistance of Soils, T. L. Youd and I. M. Idriss, eds., National Center for Earthquake Engineering Research, Buffalo, N. Y., pp.89-128 
21. Dezfulian H. (1982), 'Effects of silt content on dynamic properties of sandy soils', Proc., 8th World Conf. on Earthquake Engrg., pp.63-70 
22. Chang, N. Y., Yeh, S. T., and Kaufinan, L. P. (1982), 'Liquefaction potential of clean and silty sands', Proc.. 3rd Int. Earthquake Microzonation Corf., Vol.2, pp.1017-1032 
23. Arango, I. (1996), 'Magnitude scaling factors for soil liquefaction evaluations', J. Geotech. Engrg., ASCE, Vol.122, No.11, pp.929-936 
24. Youd, T. L. and Noble, S. K. (1997), 'Magnitude scaling factors', Proc., NCEER Workshop on Evaluation ofLiquefaction Resistance of Soils, T. L. Youd, and M. Idriss, eds., National Center for Earthquake Engineering Research, Buffalo, N. Y., pp.149-165 
25. Youd, T. L., Idriss, I. M., Andrus, R. D., Arango, I., Castro, G., Christian, J. T., Dobry, R., Finn, W. D. L., Harder, L. F., Hynes, M. E., Ishihara, K., Koester, J. P., Liao, S. S. C., Marcuson IIl, W. F., Martin, G. R., Mitchell, J. K., Moriwaki, Y., Power, M. S., Robertson, P. K., Seed, R. B., and Stokoe II, K. H. (2001), 'Liquefaction resistance of soils : Summary report from the 1996 NCEER and 1998 NCEER/NSF workshops on evaluation of liquefaction resistance of Soils', J. Geotech Engrg., ASCE, Vol.127, No.10, pp.817-833䀙—⨀ༀ䀙—⨀堙—⨀Ā堙—⨀瀙—⨀Ā瀙—⨀蠙—⨀Ā蠙—⨀ꀙ—⨀Ԁꀙ—⨀렙—⨀ 렙—⨀—⨀Ȁ—⨀܀볪ಗ⨀車䀀攀攀̀��볪ಗ⨀䌀ယ—⨀倚—⨀⃰ಗ⨀⃬ಗ⨀郲ಗ⨀Ԁ Ā렁���⨀鄏돐𐚖⨀?잖⨀���⨀椏덐���⨀栏䠏돀���⨀塨���⨀䀃���⨀뤏돐衕잖⨀怃���⨀ㄌ돀䃃���⨀塨���⨀瀁���⨀ऌ돐送���⨀?잖⨀頁���⨀덐ꠁ���⨀쀋䥮瑲慤畲慬ⵅ硴牡浥摵汬慲礠印楮慬⁃慶敲湯畳⁁湧楯浡⁡猠愠䍡畳攠潦⁓畢慲慣桮潩搠䡥浯牲桡来 
26. Ambraseys, N. N. (1988), 'Engineering seismology', Earthquake Engrg. and Struct. Dyn., Vol.17, No.1, pp.1-105 

이 논문을 인용한 문헌 (0)

1. 이 논문을 인용한 문헌 없음