High-speed Train Tunnel Research Articles

Quasi-3D Geoelectrical Imaging as A New Application for Landslide Investigations: A Tunnel Case Induced by Blasting Activity

Landslides are a significant hazard in mountainous regions, especially when influenced by construction activities such as tunnel excavation. In this paper, we aim to conduct a slope stability analysis as a result of tunnel blasts using quasi-3D subsurface models based on resistivity values. The study site is a construction area for the Jakarta-Bandung High-Speed Train tunnel, located in a mountainous region undergoing drill-and-blast excavation. This excavation method makes the area susceptible to landslides, which pose a threat to settlements in the Padalarang subdistrict, West Bandung Regency, Indonesia. Data was collected along four lines in 2D, and the dipole-dipole array was used to enhance resolution. Data modeling was carried out using ResIPy v3.2.3 software to create 2D and quasi-3D subsurface models based on resistivity values. The study findings indicate that the study area exhibits three resistivity ranges: low resistivity (0-30 Ωm), medium resistivity (31-49 Ωm), and high resistivity (>50 Ωm). Utilizing quasi-3D imaging, we were able to identify the dimensions and presence of slip surfaces, which can be categorized as shallow (1.5-5 m) and deep (5-20 m) criteria. This study successfully applied the quasi-3D geoelectrical approach in a susceptible environment to detect potential landslide zones.

Calculation grid and turbulence model for numerical simulating pressure fluctuations in high-speed train tunnel

Calculation grid and turbulence model for numerical simulating pressure fluctuations in a high-speed train tunnel are studied through the comparison analysis of numerical simulation and moving model test. Compared the waveforms and peak-peak values of pressure fluctuations between numerical simulation and moving model test, the structured grid and the SST k-ω turbulence model are selected for numerical simulating the process of high-speed train passing through the tunnel. The largest value of pressure wave amplitudes of numerical simulation and moving model test meet each other. And the locations of the largest value of the initial compression and expansion wave amplitude of numerical simulation are in agreement with that of moving model test. The calculated pressure at the measurement point fully conforms to the propagation law of compression and expansion waves in the tunnel.

A Study on the Discussions and Issues of Jeju Undersea Tunnel

최근 제주 신공항 건설에 대한 논의가 시작되면서 10여 년 전 뜨겁게 논의되다가 수면으로 가라앉은 제주해저터널에 대한 관심이 높아지고 있다. 특히 기상이변으로 인해 제주공항의 결항사태가 종종 발생하고, 시간당 36대의 항공기가 이착륙하여 영국 히드로 공항을 제외하면 세계 최고 수준으로 포화운영되는 제주공항에 대한 안전성문제가 거론되면서 새로운 고속교통망으로서 제주해저고속터널에 대한 논의가 지속되고 있다. 본고에서는 제주해저터널과 관련하여 기존 논문과 언론에서 보도된 찬반의 입장을 살펴보고 세이칸터널, 유로터널 등 외국의 주요 해저터널 건설사례를 통해 시사점을 살펴보고자 하였다. 제주해저터널과 관련한 찬반 의견은 사회적 측면, 경제적 측면, 정치적 측면으로 구분하여 각각의 논점을 분석하였으며, 특히 논란이 되고 있는 기술적 측면, 건설비용 측면, 기대효과 측면에서는 보다 상세한 쟁점을 확인하였다. 전반적으로 기술적 측면의 우려는 일부 과장된 것이 있으나, 건설비용과 기대효과는 보다 정확하고 타당성이 확보되도록 보완되어야할 여지가 있는 것으로 판단된다. 제주 신공항에 대한 논의가 구체화되는 시점에서 제주해저터널에 대한 보다 심도 깊은 논의를 기대한다.With the recent debate on the construction of a new airport in Jeju, interest in the disrupted Jeju undersea tunnel has been increasingly discussed since 10 years ago. Especially, due to the weather conditions, Jeju airport is often in disarray. Jeju Airport has 36 airplanes per hour, including the UK s Heathrow Airport, which is saturated to the world s highest level. Therefore, as the safety problem for Jeju Airport continues, discussion on Jeju undersea high speed train tunnel as new high-speed transportation network is continuing. In this paper, we examine the pros and cons of Jeju undersea tunnels, and examined the implications of construction and operation of major submarine tunnels such as Seikan Tunnel and Euro Tunnel. The opinions of pros and cons related to Jeju undersea tunnel are divided into social, economic and political aspects. In particular, we have identified more controversial issues in terms of technological aspects, construction costs, and expectations. Overall, there were some exaggerated technical concerns. However, it seems that there is room for improvement in construction cost and expected effect to be more accurate and to ensure validity. We hope that this study will provide a deeper discussion on Jeju undersea tunnels at the time when the discussions on the new port of Jeju become concrete.

3D Non-Stationary Wideband Tunnel Channel Models for 5G High-Speed Train Wireless Communications

High-speed train (HST) communications in tunnels have attracted more and more research interests recently, especially within the framework of the fifth generation (5G) wireless networks. In this paper, based on cuboid-shape, three-dimensional (3D) non-stationary wideband geometry-based stochastic models (GBSMs) for HST tunnel scenarios are proposed. By considering the influence of the tunnel walls, a theoretical channel model is first established, which assumes clusters with an infinite number of scatterers randomly distributed on the tunnel walls. The corresponding simulation model is then developed and the method of equal areas is employed to obtain the discrete parameters, such as the azimuth and elevation angles. We derive and investigate the most important channel statistical properties of the proposed 3D GBSMs, including the time-variant autocorrelation function, spatial cross-correlation function, and Doppler power spectrum density. It is indicated that all statistical properties of the simulation model, verified by simulation results, can match very well with those of the theoretical model. Furthermore, a validation is presented by comparing the stationary regions of our proposed tunnel channel model to those of relevant measurement data.

Characteristics and Mechanism Analysis of Aerodynamic Noise Sources for High-Speed Train in Tunnel

We aim to study the characteristics and mechanism of the aerodynamic noise sources for a high-speed train in a tunnel at the speeds of 50 m/s, 70 m/s, 83 m/s, and 97 m/s by means of the numerical wind tunnel model and the nonreflective boundary condition. First, the large eddy simulation model was used to simulate the fluctuating flow field around a 1/8 scale model of a high-speed train that consists of three connected vehicles with bogies in the tunnel. Next, the spectral characteristics of the aerodynamic noise source for the high-speed train were obtained by performing a Fourier transform on the fluctuating pressure. Finally, the mechanism of the aerodynamic noise was studied using the sound theory of cavity flow and the flow field structure. The results show that the spectrum pattern of the sound source energy presented broadband and multipeak characteristics for the high-speed train. The dominant distribution frequency range is from 100 Hz to 4 kHz for the high-speed train, accounting for approximately 95.1% of the total sound source energy. The peak frequencies are 400 Hz and 800 Hz. The sound source energy at 400 Hz and 800 Hz is primarily from the bogie cavities. The spectrum pattern of the sound source energy has frequency similarity for the bottom structure of the streamlined part of the head vehicle. The induced mode of the sound source energy is probably the dynamic oscillation mode of the cavity and the resonant oscillation mode of the cavity for the under-car structure at 400 Hz and 800 Hz, respectively. The numerical computation model was checked by the wind tunnel test results.

Investigation into influence of sound absorption block on interior noise of high speed train in tunnel

Investigation into influence of sound absorption block on interior noise of high speed train in tunnel

Three-Dimensional Numerical Simulation of Aerodynamic Drag on High-speed Train in Tunnel

The purpose of the paper is to derive variation law of aerodynamic drag introduced by high-speed train passing through a tunnel and to offer guidance for design of high-speed railway longitudinal section and high-speed train head shape. The paper presents a cell-centered finite volume scheme for numerical integration of Navier-Stokes equations for three-dimensional unsteady viscous compressible nonhomentropic flow to simulate the aerodynamic drag introduced by high-speed train passing through a tunnel. The aerodynamic drag curve is analysed and explained in detail in accord with the train positions．

Numerical investigation on an array of Helmholtz resonators for the reduction of micro-pressure waves in modern and future high-speed rail tunnel systems

Previous research has proposed that an array of Helmholtz resonators may be an effective method for suppressing the propagation of pressure and sound waves, generated by a high-speed train entering and moving in a tunnel. The array can be used to counteract environmental noise from tunnel portals and also the emergence of a shock wave in the tunnel. The implementation of an array of Helmholtz resonators in current and future high-speed train-tunnel systems is studied. Wave propagation in the tunnel is modelled using a quasi-one-dimensional formulation, accounting for non-linear effects, wall friction and the diffusivity of sound. A multi-objective genetic algorithm is then used to optimise the design of the array, subject to the geometric constraints of a demonstrative tunnel system and the incident wavefront in order to attenuate the propagation of pressure waves. It is shown that an array of Helmholtz resonators can be an effective countermeasure for various tunnel lengths. In addition, the array can be designed to function effectively over a wide operating envelope, ensuring it will still function effectively as train speeds increase into the future.

Numerical analysis of the slipstream development around a high-speed train in a double-track tunnel.

Analysis of the slipstream development around the high-speed trains in tunnels would provide references for assessing the transient gust loads on trackside workers and trackside furniture in tunnels. This paper focuses on the computational analysis of the slipstream caused by high-speed trains passing through double-track tunnels with a cross-sectional area of 100 m2. Three-dimensional unsteady compressible Reynolds-averaged Navier-Stokes equations and a realizable k-ε turbulence model were used to describe the airflow characteristics around a high-speed train in the tunnel. The moving boundary problem was treated using the sliding mesh technology. Three cases were simulated in this paper, including two tunnel lengths and two different configurations of the train. The train speed in these three cases was 250 km/h. The accuracy of the numerical method was validated by the experimental data from full-scale tests, and reasonable consistency was obtained. The results show that the flow field around the high-speed trains can be divided into three distinct regions: the region in front of the train nose, the annular region and the wake region. The slipstream development along the two sides of train is not in balance and offsets to the narrow side in the double-track tunnels. Due to the piston effect, the slipstream has a larger peak value in the tunnel than in open air. The tunnel length, train length and length ratio affect the slipstream velocities; in particular, the velocities increase with longer trains. Moreover, the propagation of pressure waves also induces the slipstream fluctuations: substantial velocity fluctuations mainly occur in front of the train, and weaken with the decrease in amplitude of the pressure wave.

Acoustic model of micro-pressure wave emission from a high-speed train tunnel

The micro-pressure wave (MPW) radiated from a tunnel portal can, if audible, cause serious problems around tunnel portals in high-speed railways. This has created a need to develop an acoustic model that considers the topography around a radiation portal in order to predict MPWs more accurately and allow for higher speed railways in the future. An acoustic model of MPWs based on linear acoustic theory is developed in this study. First, the directivity of sound sources and the acoustical effect of topography are investigated using a train launcher facility around a portal on infinitely flat ground and with an infinite vertical baffle plate. The validity of linear acoustic theory is then discussed through a comparison of numerical results obtained using the finite difference method (FDM) and experimental results. Finally, an acoustic model is derived that considers sound sources up to the second order and Green's function to represent the directivity and effect of topography, respectively. The results predicted by this acoustic model are shown to be in good agreement with both numerical and experimental results.

터널 환경 측정 시스템 개발 및 측정 III -솔안터널 측정결과 분석-

본 논문은 터널 환경 측정 시스템 개발 및 측정 I [1], II [2]의 후속논문이다. 본 연구의 대상이 되는 터널인 솔안터널은 백두대간을 관통하는 연장 16.7 km의 루프식 단선 터널로 산악지형에 위치하며 화물열차와 승객열차가 혼용인 일반철도 터널이다. 본 논문에서는 솔안터널의 환경 측정을 위하여 터널 내부에 3개의 위치에 설치된 환경 측정 장치에서 약 1년간 측정된 온도 및 습도를 분석하였다. 선행의 연구에서는 도심지 및 도심지 인근에 위치한 터널 내부에서 측정 결과 결과에 대하여 분석하였지만, 본 논문에서는 산악지형에 위치한 터널 내부에서 측정한 온도 및 습도 등을 외부에서의 기상 측정 결과와 비교한 것으로 선행 연구와 차별성을 지닌다. 솔안터널 내부에 측정된 온도 및 습도를 월별로 지역에서의 기상 측정 결과와 비교하였으며, 여름과 겨울을 대표하는 대표적인 일자에 대해서 철도터널에서의 시간별 온도 및 습도의 변화도 분석하였다. 또한 터널 내 측정 위치에 따른 환경 특성도 분석하였다. 본 연구에서 제시한 철도터널의 환경측정 분석 결과는 터널의 환기 및 화재 시뮬레이션 등 터널의 기류의 컴퓨터 해석 및 터널의 공기질 및 온열환경과 관련된 연구에 폭넓게 사용될 수 있다. This paper is a follow-up to previous papers entitled, "Development of Tunnel-Environment Monitoring System and Its Installation" I [1] and II [2]. The target tunnel of these studies is the Solan Tunnel, which is a loop-type, single-track, 16.7-km-long tunnel located in mountainous terrain and passing through the Baekdudaegan mountain range. It is an ordinary railway tunnel designed for both freight and passenger trains. We analyzed the environmental conditions of the tunnel using temperature and humidity data recorded over approximately one year. The data were recorded using the Tunnel Rough Environment Measuring System (TREMS), which measures environmental data in subway and high-speed train tunnels and is installed in three locations inside the tunnel. Previous studies analyzed environmental conditions inside tunnels located in or near a city, whereas the tunnel in this study is located in a mountainous area. The tunnel conditions were compared with those measured outside the tunnel for each month. Hourly changes during summer and winter periods were also analyzed, and the environmental conditions at different locations inside the tunnel were compared. The results are widely applicable in studies on the thermal environment and air quality of tunnels, as well as for computer analysis of tunnel airflow such as tunnel ventilation and fire simulations.

Monitorización de deformaciones y temperaturas en la estructura de un túnel artificial de alta velocidad mediante sensores ópticos puntuales, de longitud y distribuidos

Structural Health Monitoring (SHM) is presently having a great development. Strains and temperatures are usually the key parameters to be monitored due to their relevance when explaining structural behavior. Several types of sensors are used in SHM, but fiber optic sensors are especially interesting due to their advantages with respect to conventional sensors. In this paper, the monitoring of a high-speed train tunnel recently built in Spain using three types of fiber optic sensors developed by the authors is shown. Results given by the sensors are compared to those provided by a theoretical model built using FEM. Comparison of measurements and theoretical results confirms that the sensors reproduced remarkably well the general patterns of the tunnel structural behavior, even when strains are relatively small (around 5 μe). Finally, the paper discusses the behavior of the sensors, their measurements and their field of application which is useful for researchers and practitioners.

Deep enclosures versus pumping to reduce settlements during shaft excavations

Deep excavations in aquifers may be constructed by combining pumping with the cut and cover method. The enclosures are often deepened more than structurally needed, in order to diminish the risk of heave or fluidisation inside the excavation, and to reduce pumping rates and the associated settlements outside jet-grouting piles are sometimes adopted for lengthening.We analysed the water-proofing efficiency of jet-grouting and the need for water isolation in preconsolidated sediments. We used data obtained from two shaft excavations during the construction of the high speed train tunnel in Barcelona, located adjacent to the Sagrada Familia Basilica. Jet-grouting was characterised using pumping tests before and after the construction of the enclosure. The effectiveness of deepened enclosures was evaluated by comparing settlements caused and discharges required for several dewatering scenarios. Differences between them lie in the depth of the enclosures. Settlements were calculated analytically, using the drawdown obtained from a hydrogeological model, and numerically employing a hydro-mechanical model.Results show that jet-grouting reduced the permeability of the soil (90% reduction, from 5.5 to 0.6m/d). However, this reduction only affected the pile area, so that the necessary pumping rate and the settlements outside the enclosure were only reduced by 40%. Results also show that settlements due to groundwater pumping are fairly smooth (i.e., differential settlements are small) with low absolute values. Moreover, they recover when pumping ceases. This rather elastic and stiff behaviour reflects the preconsolidated nature of the sediments in Barcelona and the fact that drawdowns concentrate at depth, where the soil is most compact, causing little change in effective stress near the soil surface. Under these conditions, pumping does not pose a serious risk to settlements, and excavation costs can be lowered by constructing the enclosure at the minimum depth required structurally. Also, an intense control of the pumping process may help reducing the conventional safety factors against heave.

3D numerical design of tunnel hood

This paper relates to the parametric study of tunnel hoods in order to reduce the shape, i.e. the temporal gradient, of the pressure wave generated by the entry of a High speed train in tunnel. This is achieved by using an in-house three-dimensional numerical solver which solves the Eulerian equations on a Cartesian and unstructured mesh. The efficiency of the numerical methodology is demonstrated through comparisons with both experimental data and empirical formula. For the tunnel hood design, three parameters, that can influence the wave shape, are considered: the shape, the section and the length of the hood. The numerical results show, (i) that a constant section hood is the most efficient shape when compared to progressive (elliptic or conical) section hoods, (ii) an optimal ratio between hood’s section and tunnel section where the temporal gradient of the pressure wave can be reduced by half, (iii) a significant efficiency of the hood’s length in the range of 2–8 times the length of the train nose. Finally the influence of the train’s speed is investigated and results point out that the optimum section is slightly modified by the train’s speed.

Effect of Pantograph and Bogie on Interior Noise of High-Speed Train in Tunnel

For clarifying the noise in tunnel affected by pantograph and bogie, which are the most important noise sources, the noises near pantograph and bogie in a high-speed train were tested by multi-channel noise measurement and analysis system in tunnel, and compared with those measured outside the High-speed train and on an open field. The results show that the interior vehicle noise is spatially non-homogeneous in the whole carriage, the larger sound pressure level (SPL) near pantograph are next to ceiling, and near bogie next to floor. The noise spectra show a broad band feature, and dominated by the frequency contents among 100Hz-2kHz, so the countermeasures against noise should be within these range.

철도터널 진동 모니터링을 위한 광섬유 가속도계 개발

터널의 안전관리를 위해서는 효과적이고 지속적인 계측이 필요하다. 현재 적용되고 있는 대부분의 계측센서로는 터널의 국부적인 상태만을 파악할 수 있으므로 전체 터널의 안전상태를 파악하기 위해서는 다수의 설치가 필요하다. 철도터널의 경우 일정한 조건의 열차운행이 정기적으로 이루어지므로 터널구조물에 발생하는 진동을 지속적으로 관측하여 분석하면 상대적으로 넓은 범위의 영역에 대하여 터널 손상을 효과적으로 예측할 수 있다. 한편 철도터널 내에는 고전압으로 인한 전자기장의 간섭이 있으므로, 이를 배제할 수 있는 계측센서의 적용이 필요하다. 본 연구에서는 이러한 문제점을 해결하기 위하여 광섬유격자센서를 이용한 가속도계를 개발하였다. 기존 터널의 진동계측 결과를 검토하여 철도터널 진동 계측에 적합한 가속도계의 사양을 결정하였다. 민감도와 측정범위의 향상을 위하여 새로운 구조를 적용한 가속도계를 개발하였으며 실내시험을 통해 그 성능을 검증하였다. 개발된 광섬유 가속도계를 적용하여 고속철도 터널의 상시 진동모니터링 시스템을 구축한 사례를 소개하였으며, 열차운행에 의하여 발생하는 진동 측정 결과를 통해 개발된 가속도계의 유효성을 제시하였다. For the safety management of tunnel, effective measurements should be continuously carried out. Most of sensors currently being applied for tunnels measure only the local status, thus many of them are needed to monitor an entire tunnel. For the railway tunnel where trains of same conditions are regularly operated, dynamic responses of tunnel structure to train operations can be a good index to estimate the deformation of tunnel structure in wide area. Meanwhile, the electromagnetic interference caused by overhead centenary in railway tunnel obstructs the use of electric-based sensors. In this study a brand new accelerometer using FBG optical fiber sensors is developed to solve these problems. Sensitivity and capacity of the accelerometer are enhanced with effective structural design of its components and verified with laboratory tests. A case history where the developed accelerometers were applied to a safety monitoring system of a high-speed train tunnel is presented. The performances of the developed accelerometers are validated from the measured acceleration data.

Tunnel hood effects on high speed train-tunnel compression wave

This paper reports the numerical research of tunnel hood effects on high speed train-tunnel compression wave. The three-dimensional simulation with real geometry is carried out by the implementation of a commercial computational code. The train speed is 350 km/h. The train/tunnel blockage ratio is 0.115. Nine different types of tunnel hoods were studied. The calculation results showed that the hood length, the hood cross sectional area and the ventilation holes might have significant influence on the first compression wave, and inclined entry or asymmetric distribution of the ventilation holes is not available for alleviating the impulsive wave.

G0500-2-5 トンネル内を走行する新幹線車両周りの圧力・流速変動の測定([G0500-2]流体工学部門一般講演(2))

G0500-2-5 トンネル内を走行する新幹線車両周りの圧力・流速変動の測定([G0500-2]流体工学部門一般講演(2))

Countermeasures for Reducing Unsteady Aerodynamic Force Acting on High-Speed Train in Tunnel by Use of Modifications of Train Shapes

As the maximum speed of high-speed trains increases, flow-induced vibration of trains in tunnels has become a subject of discussion in Japan. In this paper, the authors report the results of a study on use of modifications of train shapes as a countermeasure for reducing an unsteady aerodynamic force by on-track tests and a wind tunnel test. First, a statistical analysis of on-track test data is conducted to identify exterior parts of a train which cause the unsteady aerodynamic force. Next, a wind tunnel test is carried out to measure the unsteady aerodynamic force acting on a train in a tunnel and train shapes are examined with a particular emphasis on the exterior parts identified by the statistical analysis. The wind tunnel test shows that fins under the car body are effective in reducing the unsteady aerodynamic force. Lastly, the fins are tested by an on-track test and its effectiveness is confirmed.

Modelling of aerodynamic force acting on high speed train in tunnel and a measure to improve the riding comfort utilising restriction between cars

For a train running at high speeds in a tunnel, the car body vibration considerably increases due to the aerodynamic force generated around the car body, thereby deteriorating riding comfort. To improve riding comfort of a train running at high speeds in a tunnel, the effects of stiffness and damping between adjoining cars are examined. In case the restriction between cars is too large, the curving performance may deteriorate around sharp curves. In this paper, analytical models of the aerodynamic force and a train are developed, and the riding comfort at high speed in a tunnel and the curving performance around a sharp curve are simulated. As a result, a solution, which improves the riding comfort at high speeds without increasing the wheel lateral force around sharp curves, is found by increasing inter-vehicle damping in the longitudinal and lateral directions.