PURPOSES : This study provides fundamental information on the temperature variations in tunnel structures during severe fire events. A fire event in a tunnel can drastically increase the internal temperature, which can significantly affect its structural safety. METHODS : Numerical simulations that consider various fire conditions are more efficient than experimental tests. The fire dynamic simulator (FDS) software, based on computational fluid dynamics (CFD) and developed by the National Institute of Standards and Technology, was used for the simulations. The variables included single and multiple accidents involving heavy goods vehicles carrying 27,000 liters of diesel fuel. Additionally, the concrete material characteristics of heat conductivity and specific heat were included in the analysis. The temperatures of concrete were investigated at various locations, surfaces, and inside the concrete at different depths. The obtained temperatures were verified to determine whether they reached the limits provided by the Fire Resistance Design for Road Tunnel (MOLIT 2021). RESULTS : For a fire caused by 27,000 liters of diesel, the fire intensity, expressed as the heat release rate, was approximately 160 MW. The increase in the carrying capacity of the fire source did not significantly affect the fire intensity; however, it affected the duration of the fire. The maximum temperature of concrete surface in the tunnel was approximately 1400 ℃ at some distance away in a longitudinal direction from the location of fire (not directly above). The temperature inside the concrete was successfully analyzed using FDS. The temperature inside the concrete decreased as the conductivity decreased and the specific heat increased. According to the Fire Resistance Design for Road Tunnel (MOLIT 2021), the internal temperatures should be within 380 ℃ and 250 ℃ for concrete and reinforcing steel, respectively. The temperatures were found to be approximately 380 ℃ and 100 ℃ in mist cases at depths of 5 cm and 10 cm, respectively, inside the concrete. CONCLUSIONS : The fire simulation studies indicated that the location of the maximum temperature was not directly above the fire, possibly because of fire-frame movements. During the final stage of the fire, the location of the highest temperature was immediately above the fire. During the fire in a tunnel with 27,000 liters of diesel, the maximum fire intensity was approximately 160 MW. The capacity of the fire source did not significantly affect the fire intensity, but affected the duration. Provided the concrete cover about 6 cm and 10 cm, both concrete and reinforcing steel can meet the required temperature limits of the Fire Resistance Design for Road Tunnel (MOLIT 2021). However, the results from this study are based on a few assumptions. Therefore, further studies should be conducted to include more specific numerical simulations and experimental tests that consider other variables, including tunnel shapes, fire sources, and locations.

Using GPR(Ground Penetrating Radar) Precise Inspection, the real lining thickness of the tunnel damage was determined and detailed analysis was performed to provide a more accurate structural safety assessment of the tunnel damage. Through this study, It is presented to provide a guide for the application of the tunnel for inspection and diagnosis.

Safety, Durability, and Usability of the Concrete Structure affecting among, there are crack and leakage the main damage is crack and leakage. Especially, Leakage is accompanied by Efflorescence, and provoke steel corrosion, exfoliation. This leakage is leaked to the exterior of the concrete surface in the shape of line or face, the method of repair varies with the shape of leakage. Accordingly, this paper will introduce case analysis of the shape of the water leakage to water leakage site in the lining structure of the NATM tunnel for utilize investigation method and basic data for the method of repair.(leakage, Efflorescence)

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).

Domestic facilities are managed in accordance with the "Special Law on the Safety and Maintenance of Facilities", and are managed through periodical inspection and safety diagnosis. In the inspection and diagnosis of such facilities, Comprehensive analysis results from exterior and non-destructive survey, and the five grade of the facility is managed. Most of the non-destructive tests are carried out in consideration of operation. In this paper, the purpose of this study is to investigate the change of compressive strength and the characteristics of the core strength in the ○○ tunnel.

It is necessary to establish countermeasures to prevent spalling in the tunnel ceiling concrete lining from being linked to lack of lining thickness, leading to additional spalling. We analyzed the effect of thinning between the ceiling part and the lining thickness on the safety of the tunnel and confirmed the structural behavior of the lining based on the measured values after practically reinforcing the inside and filling the inside of the lining.

In Korea, inspection and precise safety diagnosis is regularly carried out to maintain and manage the main tunnel(NATM) which has been passed ten years after completion. In this study, we collected the laboratory test results of the concrete lining in the existing road and railway tunnels, and analyzed the correlation between compressive strength and unit mass of concrete. It is hoped that it will be used for efficient maintenance and management work of tunnels in the future.

There is also a reverse cavity in the back of the domestic subway and railways and roads, which cause a rift in tunnel structures due to stress concentration and strain. As a result, the balsaeng of the tunnel on the back of the tunnel was interpreted as a method to determine the method of a structural structure which greatly affects the stability of the tunnel structure.

The condition assessment of the road tunnel is based on the judgment of the responsible engineer about the expansion joint. The evaluation result is divided into the span unit or the sheet unit when calculating the evaluation result. Therefore, it was divided into span units and sheet units and the actual difference was compared.

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.

There is also a reverse cavity in the back of the domestic subway and railways and roads, which cause a rift in tunnel structures due to stress concentration and strain. As a result, the balsaeng of the tunnel on the back of the tunnel was interpreted as a method to determine the method of a structural structure which greatly affects the stability of the tunnel structure.

Recently, the problem about a structural safety of the tunnel lining concrete is much raised. Thus, in this paper, We introduce a safety analysis case about an insufficient filling of the road tunnel(NATM) lining concrete for numerical analysis.

It is to confirm the various causes for cracks in concrete lining and understand the reasons for major cracks by analyzing on-site constructional conditions. Also, it is to identify the bahavior of concrete lining for its main cause of cracks.

It is largely divided into two kinds in freezing phenomenon of the tunnel. Waterproof membrane damage inside the tunnel construction joints leaked into groundwater leak occurs in the icicle and despite the absence of damage to the waterproofing membrane, waterproofing membrane from the back of the ground water is frozen freeze by interfering with smooth drainage this phenomenon is enlarged and local pressure tunnel ceiling, a crack occurred near the side wall is generated

대단면 터널 라이닝 콘크리트를 1일에 1cycle로 진행하기 위한 연구를 수행하였다. 터널 내부의 기후특성이 변화하고 콘크리트 타설온도가 낮은 경우에는 수화발현 속도도 지연되어 강도발현에 영향을 미치게 되므로 거푸집의 존치시간이 길어지게 된다. 이를 보완하기 위하여 갱문의 설치와 갱폼의 양쪽에 양생막을 설치한 후, 그 내부에 28±2℃의 추가적인 열원을 공급하게 되면 균열관리방안으로 제시한 관리기준 (4.5MPa) 이상의 조기강도발현을 이루어 낼 수 있었으며, 따라서 거푸집을 재령 14hr 후에 제거할 수가 있었다. 한편, 터널내 자연양생온도인 10±1℃ 조건에서는 콘크리트 타설 후 36hr 이상의 양생시간을 확보해야 되는 것으로 분석되었다. 본 연구를 통하여, 초기재령에서의 콘크리트 온도와 강도발현은 양생온도가 크게 작용하고 있음을 재확인 할 수 있었으며, 플라이애쉬가 10% 혼입된 콘크리트라도 일정시간동안 거푸집의 표면온도를 상승시켜 줄 수 있다면 조기강도발현에는 문제가 되지 않는 것으로 나타났다.

By comparing the computed displacement with the stress and displacement determined by entering side numbers 3, 5, and 7 into the tunnel lining inverse analysis program, the optimal number of monitoring points is determined. From the results of the research, it can be inferred that the number of monitoring points needs to be at least 5 points, considering the efficiency of monitoring in practice and the loss-and-damage rate of tunnel monitoring.

Infrastructure has been managed by precise diagnosis and repair․rehabilitation. Generally, more than 0.3mm cracks are repaired by injection method regardless of the time of repair and location of crack. In this papar, considering the feature of crack variation at three tunnels, it suggested that current diagnosis and repair methods should be improved.

Tunnel built in the late 1970 is currently being used by maintenance. For the maintenance of the tunnel, tamping materials filled backside cavity occurred during construction. In this paper, By investigating the filling state of backside cavity, It is to evaluate the filling effects of backside cavity and the adequacy of the repair and reinforcement.