Journal of the Korean Geotechnical Society (한국지반공학회논문집)

Korean Geotechnical Society (한국지반공학회)
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Evaluation of Undrained Shear Strength for Clayey Silt with Low Plasticity from the West Coast

서해안 저소성 점토질 실트 지반의 비배수 전단강도 평가

  • Kim, Seok-Jo (Dept. of Civil and Transportation Eng., Ajou Univ.) ;
  • Lee, Sang-Duk (Dept. of Civil and Transportation Eng., Ajou Univ.) ;
  • Kim, Ju-Hyun (Research Institute Affiliated with Rgeo E&C)
  • 김석조 (아주대학교 건설시스템공학과) ;
  • 이상덕 (아주대학교 건설시스템공학과) ;
  • 김주현 (알지오이엔씨 부설 기술연구소)
  • Received : 2016.03.02
  • Accepted : 2016.05.31
  • Published : 2016.08.31
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Abstract

In order to analyze undrained shear strength for clayey silt with low plasticity from Hwaseong site, a series of laboratory and in-situ tests were performed. The Unconfined Compressive (UC) test and Simple Consolidated-Undrained Triaxial (SCU) test were examined in order to assess their applicability to the measurement of the undrained strength of this soil. In the case of clayey silt with low plasticity, although the samples were properly taken by undisturbed sampling method, the residual effective stress and the unconfined compressive strength were reduced considerably. Therefore, an effective confining pressure that corresponds to the typical marine clay should be applied to the soil specimen before shearing in order to compensate for the loss of residual effective stress. By evaluating the shear strengths of clayey silt with low plasticity as 75% of $s_{u(scu)}$, the in-situ shear strength of this kind of soil can be duplicated.

화성 지역의 저소성 실트 지반에 대한 비배수 전단강도를 평가하기 위해 일련의 실내 및 현장 원위치 시험을 수행하였다. 저소성 지반에 대한 비배수 전단강도 산정을 위한 시험의 적용성을 분석하기 위해서 일축압축시험 및 간이 CU 시험을 실시하였으며, 저소성 실트 지반의 경우, 원지반에서 불교란 시료 채취가 적절하게 이루어진다 할지라고 시료 내부의 잔류유효응력이 매우 감소하게 되어, 일축압축강도가 현저하게 과소평가되는 결과가 얻어졌다. 따라서, 해성 점토 지반과 동일한 조건이 갖추어지도록 원위치 유효상재압으로 재압밀시킨 후, 전단시험에서 얻어진 간이 CU 강도, $s_{u(scu)}$의 75%를 설계 비배수 전단강도로 적용한다면, 원위치 전단강도를 적절하게 평가할 수 있는 것으로 분석되었다.

Keywords

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