Journal of the Korean Geotechnical Society (한국지반공학회논문집)

Korean Geotechnical Society (한국지반공학회)
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Development of VPPE-BE Testing System to Evaluate Modulus under Post-Compaction Variation in Matric Suction for Unsaturated Compacted Soils

다짐지반의 모관흡수력 변화에 따른 탄성계수 평가를 위한 VPPE-BE 시험 시스템 개발

  • Lee, Sei-Hyun (Dept. of Civil and Environmental Engrg., KAIST) ;
  • Seo, Won-Seok (Dept. of Civil, Architectural and Environmental Engrg., Univ. of Texas at Austin) ;
  • Choo, Yun-Wook (Dept. of Civil and Environmental Engrg., KAIST) ;
  • Kim, Dong-Soo (Dept. of Civil and Environmental Engrg., KAIST)
  • 이세현 (한국과학기술원 건설 및 환경공학과) ;
  • 서원석 (미 텍사스 오스틴 주립대학교) ;
  • 추연욱 (한국과학기술원 건설 및 환경공학과) ;
  • 김동수 (한국과학기술원 건설 및 환경공학과)
  • Published : 2008.05.31
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Abstract

The volumetric pressure plate extractor (VPPE) was modified for the measurement of shear wave velocity ($V_s$) at various levels of matric suction as well as soil water characteristic curve (SWCC). A non-destructive technique with a pair of bender element (BE) was employed in order to measure the $V_s$ and the corresponding maximum shear modulus ($G_{max}$) of unsaturated soil specimens. Three types of soil were collected from different road construction sites in Korea. For all test soils, the variations in $G_{max}$ with the various levels of water content and matric suction were investigated using the developed apparatus. Compared with the preceding results from the suction-controlled torsional shear (TS) testing system and in-situ seismic tests, the feasibility fur evaluating modulus characteristics of unsaturated compacted soils with the developed VPPE-BE system was assessed. It was confirmed that the newly developed system would be potentially helpful in modeling seasonal variation of modulus.

본 논문에서는 불포화 상태로 존재하는 다짐 지반에 대하여 함수특성곡선의 획득뿐만 아니라 다양한 모관흡수력 변화에 따른 탄성계수 평가를 위해 종래의 압력판 추출 시험기(VPPE)를 개선하였다. 이를 위해, 비파괴 시험이 가능한 벤더엘리멘트(BE) 시험 시스템을 도입하여 전단파 속도와 최대 전단탄성계수를 평가하였다. 개발된 시험 시스템을 이용하여 시공 중인 국내 도로 현장에서 채취된 3종의 노상토에 대해 모관흡수력 및 함수비 변화에 따른 최대 전단탄성계수의 변화를 평가하였다. 또한 시험결과를 기존의 모관흡수력 조절 비듦전단시험 및 현장 탄성파 시험으로부터 획득한 결과와 비교함으로써 개발된 시험 시스템의 타당성을 검증하였다. 본 연구에서 제안된 새로운 VPPE-BE 시스템은 향후, 탄성계수의 계절적 변화 모델 개발을 위한 도구로서의 효율적인 적용이 가능함을 확인하였다

Keywords

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