Journal of Korea Water Resources Association (한국수자원학회논문집)

Korea Water Resources Association (한국수자원학회)
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An experimental study on the influence of undular bore on the hydraulic stability at Shinwol rainwater storage and drainage system

불규칙 단파가 신월저류배수시설의 수리적 안정성에 미치는 영향에 대한 실험 연구

  • Oh, Jun Oh (Construction Technology and Research Center, Inje University)
  • 오준오 (인제대학교 건설기술연구소)
  • Received : 2018.07.23
  • Accepted : 2019.03.18
  • Published : 2019.05.31
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Abstract

Deep Tunnel system is a large-scale urban flood control facility installed underground in order to reinforce the lack of drainage systems in developed cities. In a structure like a deep tunnel system, the undular bore generated in the downstream causes a problem in the hydraulic stability of the tunnel. In this study, to investigate the influence of the undular bore on the hydraulic stability at the "Shinwol rainwater storage and drainage system", under construction for the first time in the country, a hydraulic model experiment was conducted on various flooding inflow scenarios. As a result of the hydraulic model experiment carried out in this study, the undular bore generated downstream is trapped in the pipe while moving to upstream, pushes the compressed air. It is judged that overflow occurred by choking the vertical drop shaft in the process when this compressed air is being exhaust through the upstream vertical drop shaft and blocking flood inflow. In addition, the analysis of velocity of undular bore shows that the undular bore transfers energy, and at this time, the pressure rose in the pipe and the velocity increment occurred of the undular bore. Further studies are needed to predict the size and velocity of undular bore, which plays an important role in the hydraulic stability of the tunnel in the deep tunnel system.

대심도 터널은 기 개발된 도시의 부족한 배수관망 능력을 보강하기 위하여 지하에 설치하는 대규모 도시홍수 배제 시설물로 역 사이펀 관로 형태를 하고 있는 시설물이다. 대심도 터널과 같은 구조에서는 하류에서 발생한 불규칙 단파에 의하여 터널의 수리적 안정성에 문제가 발생한다. 본 연구에서는 국내 최초로 건설 중인 '신월 빗물저류배수시설'의 수리적 안정성에 불규칙 단파가 미치는 영향을 알아보기 위하여 다양한 홍수유입 시나리오에 대하여 수리모형실험을 실시하였다. 본 연구에서 수행한 수리모형실험 결과 하류에서 발생한 불규칙 단파가 상류로 이동하면서 관 내 포집되어 압축상태인 공기덩어리를 밀어내는데, 이 공기덩어리가 상류 수직유입구를 통하여 급배기 되는 과정에 수직유입구를 질식시키고 홍수유입을 차단하여 월류가 발생하는 것으로 판단된다. 또한 불규칙 단파의 이동속도를 분석한 결과 불규칙 단파가 이동하면서 에너지를 전달하고 이때 관 내 압력 상승 및 불규칙 단파의 속도 증가분이 발생하는 것으로 판단된다. 대심도 터널의 수리적 안정성에 중요한 역할을 하는 불규칙 단파의 크기 및 속도 예측을 위한 추가 연구가 필요할 것으로 판단된다.

Keywords

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Fig. 1. Facilities of deep tunnel system

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Fig. 2. Flow mechanism in deep tunnel system

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Fig. 3. Concept of CRP (Celerity of bore by principle)

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Fig. 4. Concept of construction for shinwol rainwater storage and drainage system (Hyundai Construction & Engineering)

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Fig. 5. System of discharge cycle in hydraulic model experiment

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Fig. 6. Hydrograph of 50-yr. frequency of Seoul

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Fig. 7. Location of setup in piezometers

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Fig. 8. Movement of the bore to upstream

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Fig. 9. Ratio of CRP/CRO

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Fig. 10. Pressure at Junction of each scenario

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Fig. 11. Concept of CR (Celerity of resultant)

Table 1. Scales for each variables of froude similarity

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Table 2. Design conditions for experiments of each part

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Table 3. Experimental scenarios for inlet discharge and residual amount in tunnel

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Table 3. Experimental scenarios for inlet discharge and residual amount in tunnel (continue)

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Table 4. Analysis and comparison results of celerity of bores

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Table 4. Analysis and comparison results of celerity of bores (continue)

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