반복삼축시험에 의한 실트 모래 지반의 액상화 특성 연구

The Study on Liquefaction Characteristics of Silty Sand Soils by Cyclic Triaxial Test

  • 이송 (서울시립대학교 도시과학대학 토목공학과) ;
  • 전제성 (서울시립대학교 도시과학대학 토목공학과) ;
  • 김태훈 (서울시립대학교 도시과학대학 토목공학과)
  • 발행 : 1999.08.01

초록

국내 서해안 실트질 모래의 액상화 특성과 시료교란의 영향을 파악하고자 교란된 시료를 재성형하여 반복삼축시험을 수행하였다. 먼저, 실트질 모래의 응력-변형 거동에서 축변형률 $\pm10%$ 근처에서 액상화 현상이 발생했으며, 간극수압 거동은 Seed, Martin, Lysmer 등(1975)이 제안한 식과 거의 유사했다. 또한, 시료의 파괴시 dilatancy 현상을 살펴볼 수 있었다. 다음은 여러 연구자들이 제안한 액상화 평가방법들을 실시하여 그 결과를 비교했을때 액상화에 취약한 심도를 비슷하게 나타내고 있었으며, 재성형을 실시한 반복삼축시험을 통한 방법은 그 중 가장 낮은 안전율을 나타내고 있었다. 또한, 반복삼축 시험으로 구한 응력비와 경험적 방법의 표준관입시험 N값으로 구한 응력비를 비교했을때 시료교란의 영향은 N값이 20이하에서는 상대적으로 작지만, N값이 20이상일 때 교란의 효과와 시료 재성형시의 문제점 등으로 액상화 저항력과 안전율에서 큰 차이를 보였다.

The cyclic triaxial test was carried out to research liquefaction characteristics and sample disturbance effects of silty sand soils at the west coast in Korea. First, liquefaction in silty sand was generated when axial strain approached to $\pm10%$ of strain and behavior of pore pressure was similar to the formula suggested by Seed, Martin, and Lysmer(1975). Also, it was found that dilatancy was generated at failure. Secondly, the liquefaction evaluation methods suggested by many researchers were carried out and the results were compared. In these methods the weak depth in liquefaction was similar and the method carried out by cyclic triaxial test on remolded sample showed the least safety factor. Thirdly the stress ratio by cyclic triaxial test was compared with that obtained from SPT N-value as a kind of empirical methods. It was found that the effect of sample disturbance was relatively small when SPT N-value was less than 20, but there were large differences in safety factor and resistance of liquefaction in soil by the effects of disturbance and remolding when SPT N-value was more than 20.

키워드

참고문헌

  1. Principles of Soil Dynamics Das,B.M.
  2. Handbook on Liquefaction of Reclaimed Land A. A. Balkema
  3. Report No. EERC 75-14, Earthquake Engineering Research Center, University of California Determination of Soil Liquefaction Charateristics by Large-scale Laboratory Tests DeAlba;Pedro;Chan,C.K.;Seed,H.B.
  4. Report No. EERC 75-18, Earthquake Engineering Research Center, University of California The Effects of Method of Sample Preparation on the Cyclic Stress-Strain Behavior of Sands Mulilis,J.P.;Chan,C.K.;Seed,H.B.
  5. Report No. EERC 75-26, Earthquake Engineering Research Center, University of California The Generation and Dissipation of Pore Water Pressure During Soil Liquefaction Seed,H.B.;Martin,P.O.;Lysmer,J.
  6. Joural of the Geotechnical Engineering Division, ASCE v.103 no.GT7 Stabilization of Potential Liquefiable Sand Deposits Using Gravel Drains Seed,H.B.;Booker,J.R.
  7. Influence of Sample Disturbance on Sand Response to Cyclic Loading Mori;Keni;Seed,H.B.;Chan,C.K.
  8. Journal of the Geotechnical Engineering v.109 no.3 Evaluation of Liquefaction Potential Using Field Performance Data Seed,H.B.;Idriss,I.M.;Arango,Ignacio
  9. The Influence of SPT Procedures in Soil Luquefaction Resistance Evaluations Seed,H.B.;Tokimatsu,K.;Harder,L.F.;Chung,R.M.
  10. Journal of Soil Mechanics and Foundations Division, ASCE v.93 no.SM3 Analysis of Soil Liquefaction: Niigata Earthquake Seed,H.B.;Idriss,I.M.
  11. J. SMFE, ASCE v.97 no.SM97 Simplified Procedure for Evaluating Soil Liquefaction Potential Seed,H.B.;Idriss,I.M.
  12. J.GED, ASCE v.105 no.GT2 Soil Liquefaction and Cyclic Mobility Evaluation for Level Ground During Earthquakes Seed,H.B.
  13. Proc. Third ASCE /EMDE Specialty Conference, Austin Threshold Strain and Cyclic Behavior of Cohesionless Soils Dobry,R.;Swiger,W.F.
  14. International Symposium on Soils under Cyclic and Transsient Loading Liquefaction of Sands During Earthquakes the Cyclic Strain Approach Felix,Y.Y.;Dobry,R.;David,J.P.;Richard,S.L.
  15. Liquefation for S-wava Velocity Dobry,R.;Stoke,K.H.;Land,R.S.;Youd,T.L.
  16. Soils and Foundation, JSSMFE v.23 no.4 Empirical Correlation of Soil Liquefaction based on SPT N-value and Fines Content Tokimatsu,K.;Yoshimi,Y.
  17. Proceedings of 5th Japan Earthquake Engineering Syposium A Practical Method for Assessing Soil Liquefaction Potential Based on Case Studies at Various Sites in Japan Iwasaki,T.;Tatsulka,F.;Tokida,K.;Yasuda,S.