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2026 Vol.28, Issue 1

Research Paper

A numerical study on the full-face excavation of tunnel with RCS (Rebar Coupled Shotcrete)

RCS (Rebar Coupled Shotcrete)를 적용한 터널 전단면굴착에 대한 수치해석적 연구

Donghyun Kim1*
,
Jinwoo Jung2
,
Sangmin Na1
,
Sangpil Lee3
김 동현1*
,
정 진우2
,
나 상민1
,
이 상필3
1Senior Research Engineer, Geotechnical & Tunnel Engineering Team, GS E&C
2Associate Research Engineer, Geotechnical & Tunnel Engineering Team, GS E&C
3Senior Technical Advisor, Geotechnical & Tunnel Engineering Team, GS E&C
1정회원, GS건설㈜ 책임연구원
2정회원, GS건설㈜ 전임연구원
3정회원, GS건설㈜ 수석
*Corresponding Author
31 January 2026. pp. 1-20
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Abstract

RRS (Reinforced Ribs of Shotcrete) is a support method applied in poor rock mass conditions with a Q-value of 0.1 or less. It was introduced in Norway during the 1980s to replace CCA (Cast Concrete Arches) and was officially adopted as a substitute for CCA in the revised Q-System of 2012. In this study, we proposed the RCS (Rebar Coupled Shotcrete), an improved support method tailored to Korean tunneling conditions. RCS integrates rebars with rock bolts, embedding them within shotcrete to form a unified support system. With the increasing application of full-face excavation in poor rock mass conditions, driven by advances in tunneling equipment and support technologies, this research investigated the support performance of RCS in full-face excavation through numerical analysis. For this purpose, methods for estimating the elastic modulus of high-strength shotcrete and determining the composite strength of RCS are presented. The study compared and analyzed tunnel stability across various scenarios, considering rock mass classifications (grades 4-1 and 5-1), excavation methods (partial excavation and full-face excavation), support types (general shotcrete at 21 MPa, high-strength shotcrete at 35 MPa, and RCS), and tunnel depth. The results demonstrated that under full-face excavation conditions, the application of RCS improved tunnel stability.

Keywords
RRS (Reinforced Ribs of Shotcrete)
RCS (Rebar Coupled Shotcrete)
Full-face excavation
High-strength shotcrete
Tunnel numerical analysis

RRS (Reinforced Ribs of Shotcrete)는 Q값 0.1 이하의 불량한 암반 조건에서 적용되는 터널 지보 방법이다. 1980년대 노르웨이에서 CCA (Cast Concrete Arches)를 대체하기 위해 현장에 도입되었으며, 2012년 개정된 Q-System에서 공식적으로 CCA를 대체하였다. RRS를 국내 실정에 맞게 개선한 RCS (Rebar Coupled Shotcrete)는 철근을 록볼트와 연결하여 숏크리트 내부에 매립함으로써 일체화된 지보를 형성하여 터널의 안정성을 향상시킨다. 최근 터널 장비의 대형화와 지보기술의 발달로 불량한 암반에서도 전단면굴착 적용이 확대됨에 따라, 본 연구에서는 전단면굴착에서의 RCS 지보효과를 수치해석을 통해 검토하였다. 이를 위해 고강도 숏크리트의 탄성계수 산정과 RCS 합성강도 결정 방법을 제시하였고, 암반등급(4-1 type, 5-1 type), 굴착방법(분할굴착, 전단면굴착), 지보 종류(일반 숏크리트 21 MPa, 고강도 숏크리트 35 MPa, RCS), 터널 심도를 변수로 설정하여 각 해석 사례의 안정성을 비교·분석하였다. 해석 결과, 전단면굴착 조건에서 RCS 적용 시 터널 안정성이 향상되는 것을 확인하였다.

키워드
RRS (Reinforced Ribs of Shotcrete)
RCS (Rebar Coupled Shotcrete)
전단면굴착
고강도 숏크리트
터널수치해석
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Information
  • Publisher :Korean Tunneling and Underground Space Association
  • Publisher(Ko) :한국터널지하공간학회
  • Journal Title :Journal of Korean Tunnelling and Underground Space Association
  • Journal Title(Ko) :한국터널지하공간학회 논문집
  • Volume : 28
  • No :1
  • Pages :1-20
  • Received Date : 2025-11-10
  • Revised Date : 2025-12-15
  • Accepted Date : 2026-01-05
  • DOI :https://doi.org/10.9711/KTAJ.2026.28.1.001
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