In the seismic evaluation of underground utility tunnels, selecting an analytical method is critical to estimating reasonable seismic responses. In simplified pseudo-static analysis methods widely applied to typical seismic design and evaluation of underground tunnels in practice, it is essential to check whether the methods provide valid results for cut-and-cover tunnels buried in shallow to medium depth. The differences between the two simplified pseudo-static methods are discussed in this study, and the analysis results are compared to those obtained from FLAC models. In addition to the analysis methods, seismic site classification, overburden soil depth, and sectional configuration are considered variables to examine their effects on the seismic response of underground utility tunnels. Based on the analysis results, the characteristics derived from the concepts and details of each simplified model are discussed. Also, general observations are made for the application of simplified analysis methods.

This paper presents a computational fluid dynamics (CFD) analysis to investiagate the effect of expansion chamber on overpressure reduction in protective tunnels subjected to detonation of high explosives. A commercial CFD code, Viper::Blast, was used to model the blast waves in a protective tunnel with a length of 160 m, width of 8.9 m and height of 7.2 m. Blast scenarios and simulation matrix were establihsed in consideration of the design parameters of expansion chamber, including the chamber lengths of 6.1 m to 12.1 m, widths of 10.7 m to 97 m, length to width ratios of 0.0 to 5.0, heights of 8.0 m and 14.9 m, and ratios of chamber to tunnel width of 1.2 to 10.9 m. A charge weight of TNT of 1000 kg was used. The mesh sizes of the numerical model of the protective tunnel were determined based on a mesh convergence study. A parametric study based on the simulation matrix was performed using the proposed CFD tunnel model and the optimized shape of expansion chamber of the considered tunnel was then proposed based on the numerical results. Design recommendations for the use of expansion chamber in protective tunnel under blast loads to reduce the internal overpressures were finally provided.

This paper attempted to analyze the correlation between the risk image of the evacuees in the tunnel and the variables that affect the evacuation behavior due to the closed feeling. As to whether there is a difference in the level of recognizing the tunnel risk image according to the distribution of jobs, the null hypothesis was rejected at the significance probability of 0.002, so it can be said that the level of recognition of the tunnel risk image varies depending on the job group. In the distribution difference between gender and tunnel risk image recognition level, the significance probability was 0.012, indicating that the null hypothesis was rejected, indicating that the tunnel risk recognition distribution according to gender was different. As a result of analyzing the distribution difference between the tunnel's closed feeling and the tunnel risk perception level, the significance probability was 0.001, and the null hypothesis was rejected, indicating that there was a difference in the tunnel risk image level.

Backfill is one of the main components of engineered barrier in a high-level waste repository. The material selection of the backfill determines the barrier performance of the backfill. Overseas, its related research has been carried out mainly in Sweden, Finland, Canada, and Japan. However, Korea has recently started backfill research, and it is urgent to select a potential material for establishing the concept of backfill material and conducting backfill research. This study reviews NEA report, potential materials for overseas backfill research, advantages and disadvantages of single and mixed backfill materials, cases of license applications in Finland and Sweden for the selection of potential materials for backfill in Korea’s high-level waste repository. The review results indicated that it is reasonable to carry out backfill research according to the following plan: Both single and mixed materials are considered as potential materials for backfill research; experiments and performance studies are conducted with these materials; and, based on the results, a potential material or candidate material for the backfill suitable for the HLW repository in Korea is determined. For this plan, the single material is tentatively selected, as in Sweden, as bentonite with a montmorillonite content of about 40-50%. Then, if the selection criteria for montmorillonite content are determined through experiments and performance studies, we determine the final potential backfill material. As for the mixed backfill material, the bentonite/crushed rock mixture seems to be more advantageous than the bentonite/sand mixture considering the disposing problem of crushed rock generated from tunnel excavation and economic feasibility through its recycling. It is thought that the bentonite used in the bentonite/crushed rock mixture should have a higher montmorillonite content than bentonite used as a single backfill material since the crushed rock acts as an inert material in the mixture. The results of this study can be used as basic data for selecting the backfill material to be applied to the high-level waste repository in Korea, and can be used as a guideline for selecting the potential material required for backfill experiments and performance studies to be carried out in the future.

이 논문에서는 박스형 전력구의 지진응답해석에 사용되는 응답변위법(Response Displacement Method, RDM)의 보수성을 평가하였다. 이를 위하여 25가지 전력구 단면과 각 전력구에 대한 2개의 지반조건을 고려한 총 50개 예제를 선정하였다. 응답변위법에 의한 해석은 다음과 같은 세 가지 방법을 적용하였다: (1) 단일코사인방법, (2) 이중코사인방법, (3) 부지응답해석법. 그리고 이들 응답변위 법의 보수성을 평가하기 위하여 지반-구조물 상호작용을 고려한 동적해석법으로 구한 응답과 비교하였다. 비교결과, 설계지진력을 결정하는 방법 중에서 부지응답해석법이 가장 변동폭이 작았으며, 이중코사인방법이 가장 보수적인 결과를 보였다. 마지막으로 이중 코사인방법을 적용할 때, 응답변위법에 의한 부재력이 동적해석에 의한 값보다 클 확률이 80% 이상이 되기 위한 지반강성 보정계수 C값으로 기능수행수준에서 0.9, 붕괴방지수준에서 0.7을 추천하였다.

PURPOSES : This study prioritizes the potential technology for establishing an efficient traffic control in the ramp junction of urban deep underground tunnels in the future. We considered most of the applicable technologies that ensure traffic safety at the on-off ramp junction. METHODS : This study proposes a methodology to prioritize the applicable technology for establishing efficient traffic control in the ramp junction of an urban deep underground tunnel using an analytical hierarchy process (AHP). First, an AHP structure was developed. Second, an individual survey was conducted to collect the opinions of road and transportation experts. Based on the survey results, weights were estimated depending on the relevant criteria of the developed structure. The estimated weights were verified using the consistency index (CI) and consistency ratio (CR). In addition, a sensitivity analysis was performed to confirm the reliability of the estimated weights. Finally, the potential technology for an efficient traffic control in the ramp junction of an urban deep underground tunnel was prioritized. RESULTS : In the first level of hierarchy, traffic demand control had the highest priority, and ramp metering, section speed control, and shoulder lane control were selected in the second level of hierarchy. CONCLUSIONS : These results implied that prioritizing would be useful in establishing traffic operation strategies for traffic safety when constructing and opening deep underground tunnels in urban areas in the future.

The seismic deformation method is conventionally used as a seismic design for a multi-utility tunnel in Korea. In the seismic deformation method, the soil ground’s natural period is one of the most critical factors for calculating the ground displacement using cosine functions. Correction factors for the natural period and shear wave velocity have been used to consider the non-linearity of dynamic soil properties. However, the correction factors have been issued because the correction factors have not been sufficiently studied to consider Korea’s regional conditions. This paper aims to evaluate the natural periods for the seismic deformation method considering Korea’s ground conditions. Ground response analysis was performed using seven real earthquake records on twelve sites with different soil conditions where actual multi-utility tunnels are installed. As a result, natural periods of the sites were analyzed and new correction factors were proposed according to seismic performance and Korea’s regional conditions.

PURPOSES: A hard shoulder lane (HSL) is a method of solving severe traffic congestion on an expressway. Recently, it has been applied to several expressways in Korea, and there have been numerous positive effects, which include increasing the road capacity and reducing traffic congestion. However, these effects have been limited due to tunnels which created a‘ bottle-neck’effect in HSL application for longer road segments. In the tunnel sections, an HSL is generally not operational owing to problems such as narrow roads and the risk of accidents. If an HSL can be extended to tunnel segments, great positive effects can be achieved. Therefore, this study was conducted to evaluate driver behavior and stability to investigate the risk of HSL in tunnels. METHODS: The Driving Simulator experiments were conducted using some scenarios for the Geumnam and Seojong tunnels on the Seoul- Chuncheon Highway. Based on data from the experiments such as running speed, lateral replacement, and steering handling, the running stabilities of participants were analyzed. In addition, traffic flow data from VDS(Vehicle Detection System) were analyzed as before-after studies. RESULTS: Although there were some differences in driving behaviors, most participants showed safe driving behavior at a speed of less than 50 km/h. CONCLUSIONS : Based on driving behaviors and traffic flow analyses, it is concluded that HSL in tunnels can be an alternative to increase efficiency based on safe driving environments for speeds of below 50 km/h.

Tunnel is the main infrastructure in transportation system especially in Gangwon province which has 90% of its area covered by mountains. Responding to the needs for evaluating the tunnel damage in this region, the temperature inside 10 tunnels, one-way and two-way, were measured in winter by using temperature sensors. The temperatures along the length of tunnel, from the entrance until the exit, were obtained from sensors placed at 2 meters above the road. The measurement results showed the distribution of the temperature along the length of the tunnels since November 2016 until March 2017. The data showed that among all the one-way tunnels, the variation of the temperature at all positions along the length of the tunnels have almost the same gradient of temperature of all months observed. There were no significant changes between the temperatures at those points along the tunnel; whereas the changes at the entrances and the exits of the tunnels were remarkable. It was also noticed that there was the different trend of temperature variation between the one-way and two-way tunnels.

This study performs finite Element stress analysis of flange connections at noise barriers with circular steel tubes, which have a light weight. Subsequent numerical simulation results for three types of models (standard, double, and standard models strengthen by ribs) present that the applied connections for target noise barriers constructed show suitable structural performance. In this paper, the existing finite element stress analysis using the ABAQUS program is further extended to study the local stress distribution of the noise barriers with new type circular steel tubes. The numerical results for various parameters are verified by comparing different types with stresses occurred in the noise barrier from the numerical simulation.

This study presents the behavioral characteristics of submerged floating tunnels under harsh environmental conditions. To evaluate the dynamic characteristics of the submerged floating tube moored by tethers, hydrodynamic analysis was performed in time-domain. To consider the irregular wave loading condition, JONSWAP wave spectrum was used with specific significant wave height and peak period. For applying the irregular wave in the explicit dynamic analysis procedure, equivalent regular wave components which have same wave energy were applied to the external force term with random phases. According to this study, lateral and vertical motion can be effectively controlled by adjusting initial tether angle and draft. Evaluation of fatigue damage of mooring lines can be conducted by analyzing the dynamic structural stresses with appropriate S-N curves and stress concentration factors. This study also dealt with short-term fatigue analysis for checking the tethers. According to this study, cumulative fatigue damage of the tethers is definitely affected by the essential design factors such as design draft of the tunnel and tether arrangement.

지진시 사회 인프라시설물의 피해는 시설물 자체의 피해보다 사회 전반에 걸친 2차 피해를 야기한다. 그 중, 지하 공동구 구조물은 통신, 가스, 전기 등 사회의 라이프라인에 해당하여 지진에 대한 취약성을 정확히 평가하여야 할 필요가 있다. 따 라서, 본 연구에서는 지하 공동구의 지진 발생 지반가속도에 따른 파괴가능성을 평가하였다. 평가를 위한 입력지반운동은 해 외 실측 지진데이터와 한반도에서 발생가능한 인공지진파를 차용하였으며, 지진해석 방법은 응답변위법과 시간이력해석법 을 사용하였다. 파괴여부를 판별하는 한계상태는 휨모멘트와 전단 파괴를 바탕으로 하였다. 취약도 함수 도출을 위한 방법은 최우도법이 사용되었으며, 그 분포함수는 대수정규분포로 가정하였다. 이는 지진시 지하 공동구 시설물의 피해 평가는 물론 지하 공동구 시설물의 내진설계를 위한 기초자료로 활용될 수 있다.

A single-stage electrostatic precipitator (ESP) was evaluated in terms of its performance in removing dust in subway tunnels. A wire-to-plate type ESP was tested in a small-scale wind tunnel. The effects of wire-to-wire spacing (2040 mm) and the material connecting wire-to-wire on the performance of ESP were investigated, with varying applied voltage and airflow velocity. A narrower wire-to-wire spacing showed higher collection efficiency at the same applied voltage. Lower electrical resistivity of material connecting wire to wire was more effective. Ozone generation in subway tunnel applications was insignificant.

This study measured the particulate matter (PM) in a subway tunnel using a dust spectrometer and estimated the PM10 and PM2.5 using a Kriging method. For the hourly measurement, a probe was attached inside the cabin and put through the window to collect data from the outside. The Kriging method is a spatial analysis method, and time and spatial data were applied in the subway tunnel along with a PM concentration map. The result of the measurement shows that PM10 is 31.9~271.3 μg/m3 and PM2.5 is 30.9~209.5 μg/m3. In addition, The pollutant map shows that some sections have a higher concentration than other sections because of the depth and curvature of tunnel and traffic volume on the section and local construction. Also, the results show that differences concentration at different times of sampling could be distinguished. The highest concentration was found at 3 pm while the lowest was at 12 pm. We expect to use the pollutant map in planning air quality improvements for the tunnel.

In this study, we numerically analyzed flow and particle transport near the electrostatic precipitator in the tunnel according to train runs. When there was no train running, flow field was formed by a precipitator. Flow emitted from precipitator blocks the path along the tunnel, and therefore most contaminated air passes through the precipitator and can be cleaned. On the other hand, flow pattern during the train run was affected by train induced wind. A strong straight flow was generated at the front of train, and back flow was formed in the opposite line. When a train runs upward only (train start from suction section to blow section), the subway train transports contaminated particles along the tunnel. For downward train runs only case, the cleaned air reentered the contaminated section with train wind. Both train runs case showed combined flow and particle concentration pattern of both single train runs.

In this paper, the structural characteristics of a lightweight soundproof tunnel to reduce the dead load imposed on the bridge are investigated. Subsequently, the design procedure of soundproof tunnel structures is reviewed and a design practice for the lightweight soundproof tunnel is carried out according to the reviewed procedure. Next, design compatibility for the lightweight soundproof tunnel is verified through a detailed finite element analysis. The result for evaluation of design compatibility shows that the lightweight soundproof tunnel has structural safety in structural members, welding zones and foundation parts. It is also confirmed that serviceability and buckling safety is excellent.

PURPOSES : The purpose of this article is to compare and evaluate the riding comfort of a passenger in tunnels depending on different surface textures of concrete pavement. METHODS: Evaluation of riding comfort is conducted at 17 sections, which have different surface texture such as transverse tinned(TT), longitudinal tinned(LT) and diamond grinded(DG). A triaxial accelerometer was set up on the passenger seat surface of the test vehicle to measure vibrations of an occupant, then the effects of vibration on comfort and health were evaluated by ISO 2631. And microphones were installed at passenger's ears height to measure sound pressure level(SPL) in the test vehicle. Additionally, a surface microphone was installed on the inside of wheel arch to evaluate noise between tire and pavement by NCPX method. All tests were conducted cruising at 100km/h. RESULTS : The results of all tests are as follows. First, both vibration magnitudes for comfort and for health in LT and DG sections are almost same and they represent lower than those in TT sections. Second, the average SPL of DG shows the lowest decibels among them. And third, it is founded that interior noise is significantly affected by noise between tire and pavement. CONCLUSIONS : It may be concluded that DG can provide more excellent riding comfort to passenger than LT or TT. Therefore, it is necessary to consider applying DG to existing pavement surface to improve surface condition when the driving environment especially requires riding comfort like a long tunnel.