터널은 지하수 처리방법에 따라 배수형 및 비배수 방수형식으로 구분된다. 배수형 방수형식 터널은 콘크리트 라이닝 배면의 지하수에 대한 수압을 고려하지 않으므로 대단면 터널 및 얇은 라이닝 콘크리트 두께 등 터널형상 선정에서 자유롭고 경제적인 장점이 있다. 하지만 터널의 배수시스템에 문제가 생기는 경우 라이닝 콘크리트 배면에 지하수로 인한 수압으로 장기적인 측면에서 터널의 구조적 안전성에 영향을 주기 때문에 터널의 내구연한 동안 배수시스템에 대한 유지관리와 문제 발생 시 적절한 보수, 보강 방법의 적용이 필요한 실정이다.

The clogging of transverse drainage pipes in NATM tunnel is attributed to the hydraulic pressure generated on the outside of lining concrete and affects the safety of the whole structure in the long term, necessitating a keen attention in terms of its maintenance. Accordingly, this paper will introduce an analysis on the effect of the clogging of transverse drainage pipes on the lining structure based on the comparison between the inspection of the clogging of transverse drainage pipes and the visual inspection (leakage, efflorescence).

The latest precise inspection for safety and diagnosis has found the clogging of transverse drainage pipes in NATM tunnel, resulting in hydraulic pressure generated on the outside of lining concrete that poses a safety threat to the tunnel structure. Accordingly, this paper aims to conduct a safety analysis on using NATM tunnel that currently suffers the clogging of transverse drainage pipes based on its numerical analysis.

In this study, The correlation between drainage clogging of drain tunnel and leakage of lining was analyzed. As a result of analysis, the position of clogged drainage hole, leakage and efflorescence location are similar. When repairing leakage of lining, the maintenance method should be selected considering the clogging of tunnel drainage.

This study suggested an improvement of existing tunnel drainage system to prevent pavement crack, floating, rising due to tunnel seepage water at the time of heavy rains. First, we derive the main cause through case studies of poor drainage, such as pavement damage due to tunnel seepage water at the time of heavy rains, poor drainage in the changing sections of superelevation, and pipe clogging due to calcification. On this basis, we suggested four drainage improvement systems depending on the range of watering and its urgency, as follows: Drain hole drilling and installation of induced ditch, Pipe installation connected to collecting well, Installation of block out on the side of collecting well and filter layer, Installation of holes for maintaining dummy ditch. In conclusion, through such improvements suggested above, we expect that we will be able to effectively prevent pavement damage due to tunnel seepage water. Consequentially, it will also contribute improving the safety of vehicles in the expressway.

1968년 국내에 고속도로가 개통된 이후 44년 동안 한국도로공사에서 관리하는 터널은 709개소, 539,046m로 친환경 고속도로 건설추세에 맞추어 관리할 터널은 지속적으로 증가가 예상된다. 이런 공용중 터널들은 설계기준에 맞게 시공하여도 지형조건, 기타 제반여건 등이 상이하여 집중호우시 터널내 용출수 과다로 포장균열, 들뜸 및 솟음현상이 발생하여 공용중인 차량의 안전에 위험요인으로 작용하고 있어 공용중인 터널내 배수시설의 효율적인 유지관리를 위해 다각적인 배수처리방안을 수립 하고자 한다.

The priority order about a rational repair and reinforcement is generally decided by subjective decision of engineer. An appearance investigation carried out to decide about a rational repair and reinforcement through systematic and objective analysis in tunnel. we could prevent expecting leakage through several improvements in the aspects of design, materials and site implementation.