본 연구에서는 터널부의 환경조건을 고려한 터널 내부 연속철근 콘크리트 포장(CRCP)의 설계 방안을 수립하기 위하여 CRCP 전용 구조해석 프로그램을 이용하여 터널 내부와 토공부의 환경하중을 고려한 수치해석을 수행하였다. 수치해석 모델은 철근비를 0.6%와 0.68%로 고정하고 슬래브의 두께를 26cm, 28cm, 30cm로 변화시켜 구성하였다. 또한, 터널 내외 부의 환경하중과 차륜하중을 적용하여 분석을 수행하였다. 분석 결과, 터널 내외부 모든 경우에서 CRCP의 슬래브 두께 가 증가할수록 균열간격과 균열폭이 증가하게 되며 터널 내부 CRCP는 슬래브 두께를 감소시키더라도 토공부와 유사한 균열간격 및 균열폭이 형성되는 것을 확인하였다. 향후 보다 다양한 조건에서의 수치해석 및 시험시공을 통해 국내 터널 환경에 적합한 터널 내부 CRCP 설계 방안을 마련할 수 있을 것으로 기대된다.

Tunnel fires have significant social and economic impacts, causing extensive damage to concrete and steel reinforcements at high temperatures. Despite international advancements in fire-resistant designs, the safety measures for tunnel fires in South Korea remain insufficient. This study aimed to evaluate the fire resistance of fiber-reinforced concrete incorporating fire-resistant fibers with a focus on preventing spalling and enhancing structural safety. These findings are expected to contribute to the development of fire-resistant tunnel-design standards. Concrete mixtures with compressive strengths of 27 MPa were prepared according to highway construction material standards. Fiberreinforced concrete samples were produced with fire-resistant fiber dosages of 0.0, 0.6, 0.8, and 1.0 kg per cubic meter. Fresh concrete tests, including air content (KS F 2421) and slump (KS F 2402) tests, were conducted along with compressive strength tests (KS F 2405) on the hardened concrete. The fire resistance was assessed using an electric furnace to simulate the fire curve conditions specified in the Road Tunnel Fire Safety Guidelines based on KS F 2257. Increasing the fiber content led to a slight reduction in slump, likely owing to fiber agglomeration, with minimal effect on workability within the tested range. The air content exhibited negligible variation, indicating that there was no major impact on the air-void system. The compressive strength before the fire resistance test fluctuated but consistently met the design target of 27 MPa. The compressive strength after the fire resistance test across all samples decreased to approximately 2.0 MPa. The fiber-reinforced concrete exhibited reduced internal temperatures compared to the control, which was attributed to heat transfer disruption and the formation of micropores by the fibers. In this study, fiber-reinforced concrete demonstrated improved thermal resistance under fire conditions with minimal impact on the workability and air content within the tested range. Although the compressive strength before the fire resistance test remained adequate, the sharp decline in the post-fire strength highlights the need for further optimization. These findings emphasize the potential of fiber-reinforced concrete as a cost-effective solution for enhancing tunnel fire resistance, thereby supporting the development of safer and more resilient infrastructures.

The performance of various types of silencers used to reduce the micropressure waves radiated from ventilation holes and inclined shafts, which are being studied as measures to reduce micropressure waves in railway tunnels, was evaluated to find an effective silencer. In order to find the optimal silencer, the magnitude and frequency characteristics of the pressure waves emitted from the inclined shaft were analyzed to find an excellent silencer. The evaluation showed that the model with a porous cylinder and a small diameter outer tube was the simplest but performed the best.

PURPOSES : This study aims to evaluate the vertical displacement caused by differential drying shrinkage in concrete pavements within tunnels under various independent variables using structural analysis. METHODS : The behavior of differential drying shrinkage was assessed based on literature reviews of slab thickness and atmospheric humidity. The equivalent linear temperature difference (ELTD) values were analyzed using regression analysis. A three-dimensional solid element model of a two-lane highway tunnel section with six slabs was created using the ABAQUS finite element program by referring to standard drawings. Dowels and tie bars were placed in accordance with the highway standards of the Korean Highway Corporation. RESULTS : The results of a finite element analysis revealed no significant difference in vertical displacement owing to the type of slab base. However, thicker slabs exhibited a smaller vertical displacement. Additional dowels installed at the shoulder of the driving lane did not significantly inhibit vertical displacement. A narrower joint spacing resulted in a smaller vertical displacement. A comparison with field data from Tunnel A showed that the amount of differential drying shrinkage varied with the relative humidity of the atmosphere during different seasons. CONCLUSIONS : Increasing the slab thickness and reducing the joint spacing can improve driving performance by mitigating differential drying shrinkage during dry winter conditions. Future research will involve the creation of indoor test specimens to further analyze the behavior of differential drying shrinkage under varying conditions of relative humidity, slab base moisture, and wind presence.

고속도로는 콘크리트 포장을 사용하는 경우 장수명 포장을 적용하여 공용수명을 증진시키고 차단을 최소화 하여 사용자 편의성을 높이는 방향으로 패러다임이 변화하고 있다. 이때 연속철근 콘크리트 포장(이하:CRCP)는 세계적으로 검증된 장수명 포장으로 국내는 일반 토공구간에 사용하고 터널의 경우 철근으로 인한 공사차량 진입로가 확보되지 않아 JCP를 사용하고 있는 실정이다. 터널 내부는 눈비가 오는 경우에도 포장에 직접 접하지 않아 제설제를 뿌릴 필요가 없어 철근 부식의 우려가 적고 하부 지지력이 크며 온도변화가 작아 토공구간에 적용할 때 보다 공용수명이 늘어나는 장점이 있다. 터널에 CRCP를 적용하는 경우 일반구간과 다른 설계를 적용해야 하며 시험시공을 수행하기 위한 국내외 사례조사를 실시하여 적용 방향 수립에 참고하였다. 국내는 JCP 설계 지침을 통해 포장 두께 및 타이바 설치방법을 제시하나 국내 CRCP 특성을 고려하고 있지 못하고 있는 상태로 일본의 경우 일반 구간 보다 얇은 두께를 적용하며 동일한 철근비를 적용해 철근비 감소에 따라 터널 입출구에서 발생할 수 있는 배근 전이구간 발생, 열화 발생에 장점을 가지는 것으로 조사되었다. 또한, 아스콘 포장과 접하는 경우 전이슬래브를 설치하여 연결하는 것이 조사되었고 미국에서도 전이 슬래브를 통해 단부에서 발생하는 수축/팽창을 흡수하고 아스콘 포장과 접속부 역할을 할 수 있도록 하는 것이 조사되었다. 국내외 사례와 국내 CRCP의 현재 설계기준은 시험시공을 위한 설계방향 설정에 사용하는 것이 합리적으로 판단되었다. 시험시공 구간 철근비는 토공구간 기준 철근비(0.68%)와 최소 철근비(0.60%)를 적용해 계측을 통해 국내에 적합한 철근비를 도출하되 시공구간 전후에서 아스콘 포장과 연결되므로 전이슬래브를 도입/검토하여 국내에 적합한 설계를 도출하는 것이 필요한 것으로 사료되었다.

국토교통부는 고속도로 접근성 개선을 통한 지역균형 발전을 위해 남북측과 함께 동서축으로 지속적인 신설 사업을 계획하고 있다. 이에 따라 고속도로 노선의 관리 연장이 증가하고 대부분 산지인 우리나라 지형 특성에 의해 터널 구간도 증가하고 있다. 터널 구간 포장의 경우 환경 조건 등의 영향으로 전이구간에서 파손이 다수 발생하고 있다. 따라서 본 연구에서는 장대터널 구간에서 조사된 PMS 데이터를 분석하여 터널 진입 전 후 PMS 조사 인자별 변화를 분석하였다. 분석 조건은 1) 1km 이상의 장대터널 포장상태조사 자료 분석, 2) SD(Surface Distress), IRI(International Roughness Index), HPCI(Highway Pavement Condition Index) 인자 분석, 3) SD 상세 데이터(균열, 패칭, 스폴링 등) 분석이다. 이를 활용하여 터널 진입 전·후 포장 연장 변화에 대한 분석인자별 변화 검토, 터널 진입 전· 후 분석인자별 평균값 변화 비교, 터널 내 포장의 선형 균열, 패칭, 스폴링 파손 상세 검토를 수행하였다. 분석 결과 터널 진입 후 30~40m 까지 변화가 크게 나타나는 것을 확인하였으며, 평균값 비교 결과 SD 값이 진입 전 후 약 66% 차이가 나타난다. SD 상세데 이터 분석 결과는 균열 및 스폴링 파손 등에 대해 100m 구간 내에 약 3.35m2 정도 패칭보수가 이루어졌다. 장대터널의 경우 터널 입 구와 터널 내부의 환경 조건이 상이하여 전이구간에서 터널 내부보다 파손이 다수 나타나는 것을 확인하였다.

고속도로 터널 구간은 일반 도로에 비해 사고 발생 빈도와 심각도가 높으며, 특히 터널 내에서 발생하는 사고나 공사와 같은 돌발 상황은 대기 행렬을 유발해 후미 추돌 위험을 증가시킨다. 본 연구에서는 운전자가 돌발 상황 지점에 접근할 때 선제적으로 대응할 수 있도록, Driving Simulator를 활용하여 다양한 정보를 제공하는 터널 내 교통관리 시스템의 효과를 분석하였다. 분석 대상은 차로 변 경 유도, 속도 감소 유도, 돌발 상황 안내로 구성된 세 가지 교통관리 시스템의 개별 효과와 이들의 통합 운영이 터널의 안전성과 운 영 효율성에 미치는 영향을 포함하였다. 분석 결과, 세 가지 교통관리 시스템을 통해 터널 내 평균 통행 속도가 증가하였으며, 돌발 상황 발생 지점에서 차량의 차로 변경과 감속이 선제적으로 이루어지고 급감속 횟수가 현저히 감소하였다. 본 연구는 터널 내 돌발 상황 발생 시 다양한 정보를 제공함으로써 터널의 안전성과 교통흐름을 개선할 수 있음을 입증하였으며, 특히 여러 시스템을 통합적 으로 운영할 때 그 효과가 극대화됨을 Surrogate Safety Measure를 통해 확인하였다. 이러한 결과는 향후 터널 교통관리에서 단일 시스 템의 기능만을 고려하기보다는, 다양한 교통관리 시스템 간 상호작용을 고려해야 함을 시사한다.

As the distribution of vehicles and logistics increases due to the development of human civilization and the increase in population, various roads play an important role in domestic traffic and transportation. However, the recent emergence of large cities and new cities is causing traffic problems, and the increase in roads is inevitable for the smooth distribution of vehicles and logistics. In Korea, mountainous regions occupy 70% of the country, so tunnels are used to open roads. Without this, it is difficult to open the road. Currently, there are 3,720tunnels (as of December 31, 2023) installed on high-speed national highways, general national highways, and local roads nationwide, with a length of 2.499 and increasing every year. Accordingly, fire accidents in tunnels will also increase, and due to the nature of tunnel fire accidents, there is a high probability that they will escalate into large-scale disasters, resulting in casualties and property damage, as well as significant social losses due to the disruption of logistics transportation, etc. As the possibility of potential hazards is increasing, the purpose of this study is to build a safe and efficient tunnel system by optimizing maintenance and management for fire and disaster accidents in tunnels.

In recent years the tunnel construction is increasing worldwide because of development of science and technology and increasing of transportation demand. Tunnels are complex structures normally rectangular cross section or semicircular and constructed to connect between different sections of roads. Because of the importance, the construction and extension of road tunnels are also continuously increasing along with the development. According to data from the Korea Expressway Corporation, the number of road tunnels, which was 1,332 in 2010, increased rapidly by about 2.1 times over 10 years to a total of 2,742 in 2020. The extension of road tunnels is also on the trend of increasing, with a total of 945 km in 2010 reaching 2,157 km in 2020. The benefits of a double-deck tunnel are emphasized, particularly in terms of construction cost and convenience. This tunnel design incorporates a central slab, dividing the tunnel into upper and lower spaces. The versatility of a double-decker tunnel is evident in its ability to accommodate various uses for both levels. For instance, the upper level can function as vehicle roads, while the lower level can be designated for train tracks. In this study, the effect of RWS and modified hydrocarbon fire curve was applied to the concrete tunnel bracket through simulation to analyze the temperature after the fire occurrence.

본 연구는 특수한 조건에서의 줄눈 콘크리트포장의 설계 및 성능에 관한 분석을 목적으로 한다. 줄눈 콘크리트포장은 시멘트 콘크리트 포장의 한 형태로, 오랜 기간 도로 포장형식으로 사용되어 왔다. 이 포장 방식은 철근을 사용하지 않는 대신, 콘크리트 슬래브의 균열을 줄눈을 통해 유도하고, 다월바와 타이바를 통해 슬래브에 생기는 응력을 줄이는 방식이 다. 대한민국의 다양한 지역 환경과 계절적 특성은 도로 포장설계에 주요한 인자로 적용된다. 특히, 슬래브의 부등건조수 축이 평탄성 문제의 주요 원인으로 지적되며, 이는 온습도의 변화에 의해 발생한다. 본 연구에서는 3차원 유한요소해석 을 활용하여 줄눈 콘크리트포장 슬래브의 거동을 분석하고, 콘크리트 슬래브의 두께, 줄눈 간격, 타이바 및 다웰바의 배 치 등 주요 설계 변수의 영향을 평가한다. 이러한 설계 인자들이 슬래브의 응력과 변위에 미치는 영향을 확인하며, 다양 한 환경 조건 하에서의 설계 방법의 유효성을 검증한다. 본 연구는 줄눈 콘크리트포장의 실제 배치 방식을 모델링하여, 기존 설계 방식의 보안 사항을 파악하고, 설계 기준 내에서의 주요 인자 변화를 통해 부등건조수축을 완화할 수 있는 방 안을 제시한다. 이를 통해, 특수 환경 조건에서의 온습도 영향을 고려한 효율적인 포장 설계 방안을 도출함으로써, 도로 포장의 평탄성과 내구성 향상에 기여하고자 한다.

PURPOSES : This study aimed to identify factors affecting the duration of traffic incidents in tunnel sections, as accidents in tunnels tend to cause more congestion than those on main roads. Survival analysis and a Cox proportional hazards model were used to analyze the determinants of incident clearance times. METHODS : Tunnel traffic accidents were categorized into tunnel access sections versus inner tunnel sections according to the point of occurrence. The factors affecting duration were compared between main road and tunnel locations. The Cox model was applied to quantify the effects of various factors on incident duration time by location. RESULTS : Key factors influencing mainline incident duration included collision type, driver behavior and gender, number of vehicles involved, number of accidents, and post-collision vehicle status. In tunnels, the primary factors identified were collision type, driver behavior, single vs multi-vehicle involvement, and vehicles stopping in the tunnel after collisions. Incidents lasted longest when vehicles stopped at tunnel entrances and exits. In addition, we hypothesize that incident duration in tunnels is longer than in main roads due to the reduced space for vehicle handling. CONCLUSIONS : These results can inform the development of future incident management strategies and congestion mitigation for tunnels and underpasses. The Cox model provided new insights into the determinants of incident duration times in constrained tunnel environments compared to open main roads.

PURPOSES : This study investigates the factors affecting extra-long tunnel accidents by integrating data on tunnel geometry, traffic flow, and traffic accidents and derives the underlying implications to mitigate the severity of accidents. METHODS : Two processes centered on three key data points (tunnel geometry, traffic flow, and traffic accidents) were used in this study. The first is to analyze the spatial characteristics of extra-long tunnel traffic accidents and categorize them from multiple perspectives. The other was to investigate the factors affecting extra-long tunnel traffic accidents using the equivalent property-damage-only (EPDO) of individual accidents and the aforementioned data as the dependent and independent variables, respectively, by employing an ordered logistic regression model. RESULTS : Gyeonggi-do, Gyeongsangnam-do, and Gangwon-do are three metropolitan municipalities that have a significant number of extra-long tunnel accidents; Busan and Seoul have the most extra-long tunnel accidents, accounting for 23.2% (422 accidents) and 18.6% (339 accidents) of the 1,821 accidents that occurred from 2007 to 2020, respectively. In addition, approximately 70% of extra-long tunnel traffic accidents occurred along tunnels with lengths of less than 2 km, and Seoul and Busan accounted for over 60% of the top 20 extra-long tunnels with accidents. Most importantly, the Hwangryeong (down) tunnel in Busan experienced the most extra-long tunnel traffic accidents, with 77 accidents occurring during the same period. As a result of the ordered logistic regression modeling with EPDO and multiple independent variables, the significant factors affecting the severity of extra-long tunnel traffic accidents were determined to be road type (freeway, local route, and metropolitan city road), traffic flow (speed), accident time (year, summer, weekend, and afternoon), accident type (rear end), traffic law violations (safe distance violation and center line violation), and offending vehicles (van, sedan, and truck). CONCLUSIONS : Based on these results, the following measures and implications for mitigating the severity of extra-long tunnel traffic accidents must be considered: upgrading the emergency response level of all road types to that of freeways and actively promoting techniques for regulating high-speed vehicles approaching and traversing within extra-long tunnels are necessary. In addition, the emergency response and preparation system should be reinforced, particularly when the damage from extra-long tunnel traffic accidents is more serious, such as during the summer, weekends, and afternoons. Finally, traffic law violations such as safe distance and centerline violations in extra-long tunnels should be prohibited.

PURPOSES : In this study, a model was developed to estimate the concentrations of particulate matter (PM2.5 and PM10) in expressway tunnel sections. METHODS : A statistical model was constructed by collecting data on particulate matter (PM2.5 and PM10), weather, environment, and traffic volume in the tunnel section. The model was developed after accurately analyzing the factors influencing the PM concentration. RESULTS : A machine learning-based PM concentration estimation model was developed. Three models, namely linear regression, convolutional neural network, and random forest models, were compared, and the random forest model was proposed as the best model. CONCLUSIONS : The evaluation revealed that the random forest model displayed the least error in the concentration estimation model for (PM2.5 and PM10) in all tunnel section cases. In addition, a practical application plan for the model developed in this study is proposed.

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.