Journal of the Korean Geotechnical Society (한국지반공학회논문집)

Korean Geotechnical Society (한국지반공학회)
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The Strength Characteristics of Deep Mixing Ground According to Increasing Water Contents

함수비 증가에 따른 심층혼합지반의 강도특성

  • 박춘식 (창원대학교 공과대학 토목환경화공융합공학부) ;
  • 최준삼 (금보건설)
  • Received : 2019.02.26
  • Accepted : 2019.03.20
  • Published : 2019.03.31
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Abstract

A laboratory test on uniaxial compressive strength was carried out by making 640 specimens in total, which were divided into two groups by their curing time of 7 and 28 days for 3 water content conditions of a water content at 100% saturation level and 10% and 20% increased water content from the state with clay, sand and gravel mixed grounds of 20 ground conditions of 4 types of stabilizer mixing conditions which were 8%, 10%, 12%, 14%, to understand laboratory strength characteristics for strength design of deep mixing ground. In case of clayey grounds, although the strength increased depending on the increase of stabilizer content, it showed to be analogous regardless of the curing time. And the impact on the strength development of deep mixing specimen according to water content was considered to be comparatively little compared to other grounds. For sandy grounds, the strength increment amount clearly showed to increase as stabilizer content increased, and also the increase of water content was determined to be decreasing the strength increment effect. For gravel mixed grounds, at 14% or over of stabilizer content, the effect on strength development was big making a large increase in strength, but compared to sandy grounds, the strength ratio depending on the curing time showed to be small.

심층혼합지반의 강도설계를 위한 실내강도 특성을 파악하고자 점토질, 모래질, 자갈질의 20가지 지반조건, 8%, 10%, 12%, 14%의 4가지 안정재 혼합비조건, 포화도 100%에 대한 함수비와 그 때의 함수비에 10%, 20% 증가된 3가지 함수비조건에 대하여 7일 및 28일 양생기간 별로 두 개씩 총 640개의 공시체를 제작하여 일축압축강도에 대한 실내시험을 수행하였다. 점토질 지반의 경우 안정재 혼합비가 증가함에 따라 강도가 증가하지만 양생기간에는 관계없이 비슷하게 나타났으며, 심층혼합시료의 강도발현에 함수비에 대한 영향이 다른 지반에 비해 비교적 적을 것으로 판단되었다. 모래질 지반은 안정재 혼합비가 증가할수록 강도증가량이 뚜렷하게 증가하는 것으로 나타났고, 또한 함수비 증가가 강도증가 효과를 감소시키는 것으로 판단되었다. 자갈질 지반은 안정재 혼합비 14% 이상에서는 강도발현에 영향이 커서 강도증가가 크게 나타났지만 모래질 지반에 비하여 양생에 따른 강도비는 작게 나타났다.

Keywords

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Fig. 1. Strength normalization by water contents

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Fig. 2. Strength properties by curing time

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Fig. 3. Strength properties by material characteristics

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Fig. 3. Strength properties by material characteristics (Continued)

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Fig. 4. Normalization for strength of water content, S=100% (w1)

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Fig. 4. Normalization for strength of water content, S=100% (w1) (Continued)

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Fig. 5. Strength properties by sand (clay) contents

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Fig. 6. Normalization for stabilizer 8% of water content, w1

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Fig. 6. Normalization for stabilizer 8% of water content, w1 (Continued)

Table 1. Change factors of mixing ratio

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Table 2. Mixing ratio for soil type

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Table 3. Axial compressive strength of curing time 7 days

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Table 4. Axial compressive strength of curing time 28 days

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Table 6. Strength increase ratio by stabilizer content

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Table 7. Laboratory design criterion strength by water content

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Table 5. Strength decreasing ratio by water content increase

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