A Correction on Undrained Shear Strength of Disturbed Low-Plasticity Fine-Grained Soils Considering Strain Rate Effects

Yong-Gyu Lee; Min-Tae Kim; Chan-Kee Kim

doi:10.12814/jkgss.2026.25.2.001

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2026 Vol.25, Issue 2 Next Page

Research Article

A Correction on Undrained Shear Strength of Disturbed Low-Plasticity Fine-Grained Soils Considering Strain Rate Effects 변형률 속도를 고려한 교란된 저소성 세립토의 비배수 전단강도 보정 연구

30 June 2026. pp. 1-10

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Abstract

In practice, undrained shear strength obtained from laboratory tests is often underestimated due to sample disturbance; however, it is commonly applied in design without specific correction, balancing out the overestimation caused by strain rate and stress anisotropy effects. In this study, a total of 38 undisturbed soil samples were collected and subjected to uniaxial compression at various strain rates, and the degree of sample disturbance was quantitatively evaluated. In addition, compression strengths derived from field cone penetration tests conducted at the same sites were compared with the uniaxial compression strengths obtained from indoor tests, and rational correction factors were proposed to adjust the measured compression strengths. Using the commonly used strain rate of 1.0%/min as a reference, the average ranges of compression strength ratios corresponding to different strain rates were calculated, enabling the determination of strain-rate correction factors for silts and clays. Furthermore, the correction factors for these soils were recalculated by explicitly considering sample disturbance, strain rate, and stress anisotropy. Application of the recalculated correction factors resulted in excellent agreement between the compression strengths obtained from uniaxial compression tests and those inferred from field cone penetration tests.

Keywords

Undrained shear strength

Disturbance

Strain rate

실내시험을 통한 비배수 전단강도는 시료 교란으로 인해 과소평가되는 경향이 있다. 그러나 변형률 속도 및 응력이방성 효과에 의한 강도 증가 효과와 일부 상괘된다는 이유로 별도의 보정 없이 설계에 적용되는 경우가 많다. 따라서, 본 연구에서는 전라북도 정읍지역에서 38개의 불교란 시료를 채취하고 이를 변형률 속도를 달리하여 일축압축시험을 수행하였으며, 채취된 시료의 교란도를 분석하였다. 그리고 동일한 채취장소에서 현장 콘관입시험을 통해 얻은 압축강도를 실내시험에서 얻은 일축압축강도와 비교하여 합리적인 보정계수를 산정하여 채취된 시료의 압축강도를 보정하였다. 통상적으로 사용되는 1.0%/min의 변형률 속도를 기준으로 변형률 속도를 달리한 압축강도비의 평균 범위를 산정하고 이를 통해 실트와 점토의 보정계수를 산정하였다. 또한, 시료 교란의 등급, 변형률 속도 및 응력 이방성 효과에 따른 실트와 점토의 보정계수를 재산정하고 이 과정을 통해 얻은 보정계수를 사용하여 압축강도를 보정한 결과 일축압축시험에서 얻은 압축강도와 현장 콘관입시험에서 얻은 압축강도가 매우 잘 일치하는 것으로 나타났다.

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Information

Publisher :Korean Geosythetics Society
Publisher(Ko) :한국지반신소재학회
Journal Title :Journal of the Korean Geosynthetics Society
Journal Title(Ko) :한국지반신소재학회 논문집
Volume : 25
No :2
Pages :1-10
Received Date : 2026-02-26
Revised Date : 2026-05-28
Accepted Date : 2026-06-02
DOI :https://doi.org/10.12814/jkgss.2026.25.2.001

Journal of the Korean Geosynthetics Society ISSN:2508-2876(Print) 2287-9528(Online) 한국지반신소재학회 논문집

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