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

Korean Tunnelling and Underground Space Association (한국터널지하공간학회)
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Study on EPB TBM performance by conducting lab-scaled excavation tests with different foam injection for artificial sand

실내 굴진 시험을 통한 폼 주입 조건에 따른 인공 사질토 지반에서 EPB TBM 굴진성능에 대한 고찰

  • Lee, Hyobum (School of Civil, Environmental and Architectural Engineering, Korea University) ;
  • Shin, Dahan (School of Civil, Environmental and Architectural Engineering, Korea University) ;
  • Kim, Dae-Young (Dept. of R&D, Hyundai Engineering & Construction) ;
  • Shin, Young Jin (Dept. of R&D, Hyundai Engineering & Construction) ;
  • Choi, Hangseok (School of Civil, Environmental and Architectural Engineering, Korea University)
  • 이효범 (고려대학교 건축사회환경공학부) ;
  • 신다한 (고려대학교 건축사회환경공학부) ;
  • 김대영 (현대건설 연구개발본부) ;
  • 신영진 (현대건설 연구개발본부) ;
  • 최항석 (고려대학교 건축사회환경공학부)
  • Received : 2019.05.16
  • Accepted : 2019.07.05
  • Published : 2019.07.31
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Abstract

During EPB TBM tunnelling, an appropriate application of additives such as foam and polymer is an essential factor to secure the stability of TBM as well as tunnelling performance. From the '90s, there have been many studies on the optimal injection of additives worldwidely contrary to the domestic situation. Therefore, in this paper, the foam, which is widely adopted for soil conditioning, was selected as an additive in order to investigate the effect of foam injection on TBM performance through a series of laboratory excavation tests. The excavation experiments were carried out on artificial sandy soil specimens with consideration of the variance of FIR (Foam Injection Ratio), FER (Foam Expansion Ratio) and $C_f$ (Surfactant Concentration), which indicate the amount and quality of the foam. During the tests, torque values were measured, and the workability of conditioned soil was evaluated by comparing the slump values of muck after each experiment. In addition, a weight loss of the replaceable aluminum cutter bits installed on the blade was measured to estimate the degree of abrasion. Finally, the foam injection ratio for the optimal TBM excavation for the typical soil specimen was determined by comparing the measured torque, slump value and abrasion. Note that the foam injection conditions satisfying the appropriate level of machine load, mechanical wear and workability are essential in the EPB TBM operational design.

EPB TBM 굴진 중 다양한 지반 조건에서 적절한 양의 폼(Foam), 폴리머(Polymer) 등 첨가제의 주입은 TBM 공사의 안정성은 물론 굴진 성능을 결정하는 중요한 요소이다. 국외에서는 90년대부터 최근까지 EPB TBM 공법을 토사 지반에 적용할 때 최적의 첨가제 주입에 대한 연구가 활발하게 이루어졌으나 국내에서는 이와 관련된 연구가 매우 부족한 실정이다. 따라서 본 연구에서는 굴착토 컨디셔닝에 가장 널리 사용되는 폼을 첨가제로 선정하고 폼 주입에 따른 토사 지반에서의 TBM 굴진 성능 변화를 일련의 실내 굴진 시험을 통해 파악하였다. 굴진 시험은 인공 사질토 지반을 동일 다짐 조건으로 조성하고 폼의 주입량과 상태를 나타내는 변수인 FIR (Foam Injection Ratio), FER (Foam Expansion Ratio), $C_f$ (Surfactant Concentration) 값을 변화시켜가며 수행되었으며, 각 시험에서 굴진 중 측정된 토크 값을 측정하였다. 또한 굴진 시험 후, 배토된 흙의 슬럼프 값을 비교하여 컨디셔닝 된 시료의 워커빌리티(workability)를 평가하였으며, 블레이드에 설치된 알루미늄 커터의 무게 변화를 측정하여 컨디셔닝 조건에 따른 동일 위치에서의 커터 마모량을 비교하였다. 최종적으로 측정된 토크, 슬럼프 값, 마모량 결과의 비교를 통해 본 연구에서 적용된 인공 사질토 지반에서 최적 TBM 굴진을 위한 폼 주입비를 도출하였다. 연구 결과를 통해 지반 조건에 따라 다른 최적의 TBM 굴진 성능을 확보하기 위해서는 장비 부하, 기계 마모, 워커빌리티 확보에 대하여 적정 수준을 만족하는 폼 주입 조건이 존재하고 이에 대응하기 위한 사전 폼 주입 설계가 필요한 것으로 나타났다.

Keywords

TNTNB3_2019_v21n4_545_f0001.png 이미지

Fig. 1. Composition of laboratory EPB TBM excavation test apparatus

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Fig. 2. Particle size distribution of artificial sand for the experiment

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Fig. 3. Comparison of torque values with different FIR (torque)

TNTNB3_2019_v21n4_545_f0004.png 이미지

Fig. 4. Change of weight of bits with different FIR (abrasion)

TNTNB3_2019_v21n4_545_f0005.png 이미지

Fig. 5. Slump values of muck with different FIR (slump)

TNTNB3_2019_v21n4_545_f0006.png 이미지

Fig. 6. Comparison of torque values with different FER (torque)

TNTNB3_2019_v21n4_545_f0007.png 이미지

Fig. 7. Change of weight of bits with different FER (abrasion)

TNTNB3_2019_v21n4_545_f0008.png 이미지

Fig. 8. Slump values of muck with different FER (slump)

TNTNB3_2019_v21n4_545_f0009.png 이미지

Fig. 9. Comparison of torque values with different Cf (torque)

TNTNB3_2019_v21n4_545_f0010.png 이미지

Fig. 10. Change of weight of bits with different Cf (abrasion)

TNTNB3_2019_v21n4_545_f0011.png 이미지

Fig. 11. Slump values of muck with different Cf (slump)

Table 1. Properties of foam surfactant for laboratory experiment

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Table 2. Laboratory test cases of EPB TBM excavation considering foam injection condition

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Table 3. Summary of laboratory excavation test results

TNTNB3_2019_v21n4_545_t0003.png 이미지

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