Journal of Korean Tunnelling and Underground Space Association (한국터널지하공간학회 논문집)

Korean Tunnelling and Underground Space Association (한국터널지하공간학회)
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A simple test method to evaluate workability of conditioned soil used for EPB Shield TBM

토압식 쉴드 TBM 굴진을 위한 화강풍화토의 컨디셔닝을 평가하는 간편 시험법

  • Kim, Tae-Hwan (School of Civil, Environmental and Architectural Engineering, Korea University) ;
  • Kwon, Young-Sam (School of Civil, Environmental and Architectural Engineering, Korea University) ;
  • Chung, Heeyoung (School of Civil, Environmental and Architectural Engineering, Korea University) ;
  • Lee, In-Mo (School of Civil, Environmental and Architectural Engineering, Korea University)
  • 김태환 (고려대학교 건축사회환경공학부) ;
  • 권영삼 (고려대학교 건축사회환경공학부) ;
  • 정희영 (고려대학교 건축사회환경공학부) ;
  • 이인모 (고려대학교 건축사회환경공학부)
  • Received : 2018.09.11
  • Accepted : 2018.10.12
  • Published : 2018.11.30
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Abstract

Soil conditioning is one of the key factors for successfull tunnel excavations utilizing the earth pressure-balanced (EPB) shield tunnel boring machine (TBM) by increasing the tunnel face stability and extraction efficiency of excavated soils. In this study, conditioning agents are mixed with the weathered granite soils which are abundant in the Korean peninsula and the workability of the resulting mixture is evaluated through the slump tests to derive and propose the most suitable conditioning agent as well as the most appropriate agent mix ratios. However, since it is cumbersome to perform the slump tests all the time either in the laboratory or in-situ, a simpler test may be needed instead of the slump test; the fall cone test was proposed as a substitute. In this paper, the correlation between the slump value obtained from the slump test and the cone penetration depth obtained from the proposed fall cone test was obtained. Test results showed that a very good correlation between two was observed; it means that the simpler fall cone test can be used to assess the suitability of the conditioned soils instead of the more cumbersome slump test.

토압식(Earth Pressure Balanced, EPB) 쉴드 TBM 굴착에서 첨가제 사용을 통해 막장 안정과 배토효율을 증대시키며, 토사지반에의 적용범위를 확대시킬 수 있다. 첨가제로 배합된 굴착토사는 배합 전과 그 거동을 달리하는데, 일반적으로 워커빌리티를 평가하여 비교할 수 있다. 본 연구에서는 국내 화강풍화토와 첨가제를 배합한 후 슬럼프 시험을 통해 워커빌리티를 평가하고, 적절한 배합비를 도출하고자 하였는바, 매 경우마다 슬럼프 시험을 실시하는 것이 많은 노력을 요하므로 실내 혹은 현장에서 슬럼프 시험보다 간편한 시험법이 필요하다고 판단되어 대체 실험으로서 낙하 콘 시험을 고안하였다. 같은 시료에 대하여 슬럼프 시험에 의한 슬럼프 치와 낙하 콘 시험에서의 콘 관입깊이와의 상관관계를 구한 결과 매우 상관성이 높음을 알 수 있었다. 따라서 국내에 편재해있는 화강풍화토에 대한 쏘일 컨디셔닝의 평가에 핵심인 슬럼프 치 대신 낙하 콘 시험을 이용할 수 있는 관계식을 제안하였다.

Keywords

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Fig. 1. Experimental apparatus used in laboratory-scale tests

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Fig. 2. Flow rate of foam versus FER

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Fig. 3. Particle size gradation curves of the two weathered granite soils

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Fig. 4. Soil samples with the variation of water content and FIR

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Fig. 4. Soil samples with the variation of water content and FIR (continue)

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Fig. 5. Slump values with the variation of water content and FIR

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Fig. 6. Cone penetration depth with the variation of water content and FIR

TNTNB3_2018_v20n6_1049_f0008.png 이미지

Fig. 7. Slump value and cone penetration depth correlation

Table 1. Physical properties of two types of weathered granite soils

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Table 2. Properties of the foam used in the experiment (Kim et al., 2018)

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Table 3. Slump values and cone penetration depths of conditioned soils

TNTNB3_2018_v20n6_1049_t0003.png 이미지

References

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