The detection of crack defects on the walls of road tunnels is a crucial step in the process of ensuring travel safetyand performing routine tunnel maintenance. The automatic and accurate detection of cracks on the su...The detection of crack defects on the walls of road tunnels is a crucial step in the process of ensuring travel safetyand performing routine tunnel maintenance. The automatic and accurate detection of cracks on the surface of roadtunnels is the key to improving the maintenance efficiency of road tunnels. Machine vision technology combinedwith a deep neural network model is an effective means to realize the localization and identification of crackdefects on the surface of road tunnels.We propose a complete set of automatic inspection methods for identifyingcracks on the walls of road tunnels as a solution to the problem of difficulty in identifying cracks during manualmaintenance. First, a set of equipment applied to the real-time acquisition of high-definition images of walls inroad tunnels is designed. Images of walls in road tunnels are acquired based on the designed equipment, whereimages containing crack defects are manually identified and selected. Subsequently, the training and validationsets used to construct the crack inspection model are obtained based on the acquired images, whereas the regionscontaining cracks and the pixels of the cracks are finely labeled. After that, a crack area sensing module is designedbased on the proposed you only look once version 7 model combined with coordinate attention mechanism (CAYOLOV7) network to locate the crack regions in the road tunnel surface images. Only subimages containingcracks are acquired and sent to the multiscale semantic segmentation module for extraction of the pixels to whichthe cracks belong based on the DeepLab V3+ network. The precision and recall of the crack region localizationon the surface of a road tunnel based on our proposed method are 82.4% and 93.8%, respectively. Moreover, themean intersection over union (MIoU) and pixel accuracy (PA) values for achieving pixel-level detection accuracyare 76.84% and 78.29%, respectively. The experimental results on the dataset show that our proposed two-stagedetection method outperforms other state-of-the-art models in crack region localization and detection. Based onour proposedmethod, the images captured on the surface of a road tunnel can complete crack detection at a speed often frames/second, and the detection accuracy can reach 0.25 mm, which meets the requirements for maintenanceof an actual project. The designed CA-YOLO V7 network enables precise localization of the area to which a crackbelongs in images acquired under different environmental and lighting conditions in road tunnels. The improvedDeepLab V3+ network based on lightweighting is able to extract crack morphology in a given region more quicklywhile maintaining segmentation accuracy. The established model combines defect localization and segmentationmodels for the first time, realizing pixel-level defect localization and extraction on the surface of road tunnelsin complex environments, and is capable of determining the actual size of cracks based on the physical coordinatesystemafter camera calibration. The trainedmodelhas highaccuracy andcanbe extendedandapplied to embeddedcomputing devices for the assessment and repair of damaged areas in different types of road tunnels.展开更多
an air cleaner employing pulse induced plasma chemical process to remove dust and carbon monoxide (CO) in road tunnels is presented, which is composed of mainly a precipitator, a reactor, a flow control system, a powe...an air cleaner employing pulse induced plasma chemical process to remove dust and carbon monoxide (CO) in road tunnels is presented, which is composed of mainly a precipitator, a reactor, a flow control system, a power supply and a measurement system. Its performances are studied in simulated air conditions. It is found that the rate of dust removal is dependent on the voltage of the pulse power, the distance between the two dust collecting plates of the electrostatic precipitator, the effective length of the precipitator and the air flow rate in the precipitator, and that of CO removal is affected by the voltage and frequency of the super pulse power, the air flow rate in the reactor and the relative humidity of air. Applying such an cleaner of a proper design to the treatment of polluted air at a flow rate of 7 m/s can achieve the rate of dust removal up to 93 % and that of CO removal up to 72.6 %, which efficiently controls the concentrations of CO and dust under allowable limits. It is implied that the proposed air cleaner is a potential solution to air control in road tunnels, and is prominent for its performances and saving the huge cost of longitudinal ventilation tunnel or vertical vent and ventilation facilities.展开更多
Road tunnel excavation often traverses coal strata, which is at risk of firedamp explosion that usually results in disaster. Airtight concrete grouting is popularly used in this kind of tunnel project. Based on the es...Road tunnel excavation often traverses coal strata, which is at risk of firedamp explosion that usually results in disaster. Airtight concrete grouting is popularly used in this kind of tunnel project. Based on the essential theory of mechanics of fluids in porous media, the principle of improving concrete airtight property and its influential factors are investigated. The proportioning tests and monitoring method for airtight concrete are introduced, which is illustrated by a case study applied to the project of the Huayinshan Tunnel. It is proved by engineering practices that the achievement of this research work is beneficial to tunneling project across coal strata.展开更多
In the USA,risk-based decision making has not been a common approach to tunnel safety in the past,but this is changing,as concepts such as“equivalency”in the NFPA 502 framework gain acceptance in the USA and elsewhe...In the USA,risk-based decision making has not been a common approach to tunnel safety in the past,but this is changing,as concepts such as“equivalency”in the NFPA 502 framework gain acceptance in the USA and elsewhere.In other regions,in particular in Europe,risk assessment techniques have been used for nearly two decades in many jurisdictions as an additional tool to complement the application of prescriptive guidelines and support decisions related to tunnel safety.After some initial difficulties these methods are meanwhile a well-established element of tunnel safety management.There are several tools available which have been practically applied and further developed over years,such as the Austrian tunnel risk model TuRisMo,or the PIARC owned DG-QRAM model.Whereas TuRisMo is a holistic,system-based model,which is best suited to quantify and assess fire risk and associated mitigation measures,DG-QRAM focusses on the risks related to the transport of hazardous materials.Depending on the objectives and the scope of the investigation and the regulatory environment,tunnel risk assessment tools are in use for different purposes,mainly to demonstrate a sufficient level of safety and to decide on and select(additional)risk mitigation measures.The international experience substantiates that the general approach is flexible and that the methods and tools are mature and can be applied for different problems in different environments.First case studies like the risk study on conditions and permissibility of the transport of hazardous materials through the Eisenhower-Johnson-Memorial Tunnel in Colorado demonstrate the applicability of a risk-based concept for decision making in the US-American environment.展开更多
After some tragic fire events,Directive 2004/54/EC was issued to ensure a minimum safety level for tunnels belonging to the Trans-European Road Network longer than 500 m.Nowadays,most of the Italian road tunnels are s...After some tragic fire events,Directive 2004/54/EC was issued to ensure a minimum safety level for tunnels belonging to the Trans-European Road Network longer than 500 m.Nowadays,most of the Italian road tunnels are still not in compliance with the minimum safety requirements,thus refurbishment works are often planned.By developing a traffic macro-simulation model,this paper aims at assessing the resilience of an existing twin-tube motorway tunnel when one of its tubes is partially or completely closed due to planned activities.Several scenarios were investigated,also considering the availability or not of an alternative itinerary in the surrounding transportation network.The average vehicles’speed was used as a functionality parameter,while the resilience metrics were the resilience loss,the recovery speed,and the resilience index.The findings showed higher resilience losses for complete closure rather than partial closure of the tube under planned refurbishment works.The implementation of digital technologies,such as variable message signs,might reduce the resilience loss of the tunnel system.This research might represent a reference for tunnel management agencies in the choice of the most appropriate traffic control strategy to improve tunnel resilience in the event of planned activities.展开更多
The analysis of the fluid characteristics downstream of a fire source in transportation tunnels is one the most important factor in the emergency response, evacuation, and the rescue service studies. Some crucial para...The analysis of the fluid characteristics downstream of a fire source in transportation tunnels is one the most important factor in the emergency response, evacuation, and the rescue service studies. Some crucial parameters can affect the fluid characteristics downstream of the fire. This research develops a statistical analysis on the computational fluid dynamics(CFD) data of the road tunnel fire simulations in order to quantify the significance of tunnel dimensions, inlet air velocity, heat release rate, and the physical fire size(fire perimeter) on the fluid characteristics downstream of the fire source. The selected characteristics of the fluid(response variables) were the average temperature, the average density, the average viscosity, and the average velocity. The prediction of the designed statistical models was assessed; then the significant parameters' effects and the parameters interactive effects on different response variables were determined individually. Next, the effect of computational domain length on the selection of the significant parameters downstream of the fire source was analyzed. In this statistical analysis, the linear models were found to provide the statistically good prediction. The effect of the fire perimeter and the parameters interactive effects on the selected response variables downstream of the fire, were found to be insignificant.展开更多
In some cases coal measures,goaf,big caves,and huge faults,as well as high initial stress cannot be avoided in road tunnel excavation.These geological features may make it more difficul practical tunnel construction. ...In some cases coal measures,goaf,big caves,and huge faults,as well as high initial stress cannot be avoided in road tunnel excavation.These geological features may make it more difficul practical tunnel construction. So it is necessary to take strong precautious measures against gas outburst,water bursting and roof fall in a tunnel across coal measures with risk of gas outburst.The techniques,such as advance drilling exploration,multiple-cycle shallow depth hole controlled blasting,reinforced supporting,which include concrete grouting and twice supporting,and monitoring measures are often applied in the construction of tunnels and satisfied results are achieved. Results in this paper can help others to get experiences in road tunnel construction with similar geological features.展开更多
The tunnel pavement is generally made of asphalt or concrete.Due to the relatively fixed material of pavement,the effect of tunnel pavement setting on the lighting environment and visual performance of drivers has not...The tunnel pavement is generally made of asphalt or concrete.Due to the relatively fixed material of pavement,the effect of tunnel pavement setting on the lighting environment and visual performance of drivers has not received sufficient attention,especially the impact on the visual performance of drivers during driving has not been revealed.Therefore,experimental research on the visual recognition performance of an obstacle on asphalt and concrete pavements inside tunnels during dynamic driving was conducted in this study.The results indicate that under the same pavement illumination,the luminance on concrete pavement is higher than that on asphalt pavement due to the higher reflectance of concrete.The visible distance of the human eyes for a gray obstacle with a reflectance of 0.2 on the concrete pavement is greater than that on the asphalt pavement,and the visible distance of the obstacle on the concrete pavement increases by more than 28%.When the color of the obstacle and the pavement are close,it can be challenging for observers to recognize the obstacle,and the pavement and obstacle need to have a higher level of luminance for the recognition.During dynamic driving,the visible distance at a speed of 60 km/h is 1.2 to 1.4 times that at a speed of 80 km/h,which means the influence of vehicle speed on the human eye’s recognition of obstacles on asphalt and concrete pavements should be taken into consideration in the design of road tunnel lighting.The correlated color temperature and S/P value of LED light have little impact on the visible distance of human eyes to the obstacle on the asphalt and concrete pavements,but it does create different visual perceptions.As the correlated color temperature and S/P value increase,the lighting environment of the tunnel gradually gives a brighter feeling to drivers.展开更多
Road pavements in tunnels are usually made of asphalt mixtures,which,unfortunately,are flammable materials.Hence,this type of pavement could release heat,and more specifically smoke,in the event of a tunnel fire,there...Road pavements in tunnels are usually made of asphalt mixtures,which,unfortunately,are flammable materials.Hence,this type of pavement could release heat,and more specifically smoke,in the event of a tunnel fire,thereby worsening the environmental conditions for human health.Extensive research has been conducted in recent years to enhance the fire reaction of traditional asphalt mixtures for the road pavements used in tunnels.The addition of the Flame Retardants(FRs)in conventional asphalt mixtures appears to be promising.Nevertheless,the potential effects of the FRs in terms of the reduction in consequences on tunnel users in the event of a large fire do not seem to have been sufficiently investigated by using fluid dynamics analysis as a computational tool.Given this gap of knowledge,this article aims to quantitatively evaluate whether the use of flame-retarded asphalt mixtures,as opposed to traditional ones without FRs,might mitigate the adverse effects on the safety of evacuees and fire brigade by performing numerical analyses in the case of a tunnel fire.To achieve this goal,3D Computational Fluid Dynamics(CFD)models,which were executed using the Fire Dynamics Simulator(FDS)tool,were established in the case of a major fire of a Heavy Goods Vehicle(HGV)characterized by a maximum Heat Release Rate(HRRmax)of 100 MW.The people evacuation process was also simulated,and the Evac tool was used.Compared to the traditional asphalt pavements without FRs,the simulation findings indicated that the addition of the FRs causes a reduction in CO and CO_(2)levels in the tunnel during the aforementioned fire,with a minor number of evacuees being exposed to the risk of incapacity to self-evacuate,as well as certain safety benefits for the operability of the firefighters entering the tunnel downstream of the fire when the tunnel is naturally ventilated.展开更多
In this article,the processes of vans running into a one-way two-lane road tunnel are simulated numerically using the dynamic mesh technique and RNG k ？ ε turbulence model.The transient aerodynamic characteristics a...In this article,the processes of vans running into a one-way two-lane road tunnel are simulated numerically using the dynamic mesh technique and RNG k ？ ε turbulence model.The transient aerodynamic characteristics around vans are obtained in three cases：a single van,two vans side-by-side and two vans one after another running into the tunnel,respectively.Through a comparison with the results of the wind tunnel experiment,the transient simulation method is verified.The results show that,when a van runs into the tunnel,the aerodynamic drag coefficient increases near the tunnel entrance,and after entering the tunnel,the side force is generated,pointing to the tunnel wall nearer to the van.When two vans run into the tunnel side-by-side,their drag coefficients increase by 50%,and the side force varies sharply with directions changing twice near the tunnel entrance.When two vans run into tunnel one after another,the aerodynamic characteristics around the van in the front is similar to that of a single van,but the aerodynamic forces on the van behind do not have obvious change.Among the three cases,the aerodynamic forces have a sharp change when two vans run side-by-side,so driving side-by-side into a tunnel should be avoided for safety.展开更多
Road tunnels consume a large amount of energy,especially in the Canadian cold climate,where the roads are heated electrically or deicing during the winter.For a more sustainable and resilient road tunnel energy system...Road tunnels consume a large amount of energy,especially in the Canadian cold climate,where the roads are heated electrically or deicing during the winter.For a more sustainable and resilient road tunnel energy system,we conducted an exploratory study on installing a semi-transparent photovoltaic(STPV)canopy at the entrances and exits of a tunnel under a river.The proposed system generates solar-powered electricity,improves thermal and visual conditions,and reduces energy loads.In this study,field measurements of road surface temperature and air temperature were conducted,and numerical simulations with and without STPV were performed to study air and road surface temperatures under different traffic speeds.The field measurements show the road surface temperatures are higher than the air temperature on average.The interior air and road surface temperature were measured to be above 0°C,even though the outdoor temperature is far below 0°C,thus significantly reducing the need for deicing in winter using salts.The simulations show that the air and surface temperatures elevate due to the solar transmission heat through the STPV canopy,thus reducing deicing energy consumption significantly.The fire safety analysis also showed that the proposed system's top opening should be located near the tunnel entrance instead of the canopy entrance for better smoke exhaust during a fire.展开更多
Prefabricated internal structures of road tunnels,consisting of precast elements and the connections between them,provide advantages in terms of quality control and manufacturing costs.However,the limited construction...Prefabricated internal structures of road tunnels,consisting of precast elements and the connections between them,provide advantages in terms of quality control and manufacturing costs.However,the limited construction space in tunnels creates challenges for on-site assembly.To identify feasible connecting joints,flexural tests of precast straight beams connected by welding-spliced or lap-spliced reinforcements embedded in normal concrete or ultra-high-performance fiber-reinforced concrete(UHPFRC)are first performed and analyzed.With an improvement in the strength grade of the closure concrete for the lap-spliced joint,the failure of the beam transforms from a brittle splitting mode to a ductile flexural mode.The beam connected by UHPFRC100 with short lap-spliced reinforcements can achieve almost equivalent mechanical performance in terms of the bearing capacity,ductility,and stiffness as the beam connected by normal concrete with welding-spliced reinforcements.This favorable solution is then applied to the connection of neighboring updeck slabs resting on columns in a double-deck tunnel.The applicability is validated by flexural tests of T-shaped joints,which,fail in a ductile fashion dominated by the ultimate bearing capacity of the precast elements,similar to the corresponding straight beam.The utilization of UHPFRC significantly reduces the required lap-splice length of reinforcements owing to its strong bonding strength.展开更多
Selecting fires safety measures for road tunnels relies mainly on strict regulatory requirements. However, the choice should also be based on many different criteria and ranking of alternatives should take place. Exis...Selecting fires safety measures for road tunnels relies mainly on strict regulatory requirements. However, the choice should also be based on many different criteria and ranking of alternatives should take place. Existing methods exhibit lack in dealing rigorously with measures’ selection amongst different alternatives. This paper contributes to the body of knowledge by proposing a novel method, named EVADE, which aims to incorporate diverse stakeholders’ views and provide a meaningful ranking of alternatives.To do so, it estimates the tunnel level of safety taking into account only any standard measures existing. Subsequently, the performance of additional measures is examined.Then, a list of the most significant criteria that are valuable to judge the appropriateness of selected measures is introduced. The relative importance amongst the decision criteria is calculated through the Analytic Hierarchy Process, based on the expert opinion. Sensitivity analysis through Monte Carlo simulation is embedded to allow for a meaningful prioritization of the decision criteria. Thus, the alternatives’ ranking comes as a distribution instead of a single number, providing the decision-maker richer information for selecting the most suitable measure(s) according to the specific tunnel situation. At last, a typical tunnel is examined to showcase the utilization of the method.展开更多
Based on the opening baffle mode for natural ventilation of city road tunnels,this paper studies the impacts of opening baffle on natural ventilation performance by verifying numerical simulation through model tests.B...Based on the opening baffle mode for natural ventilation of city road tunnels,this paper studies the impacts of opening baffle on natural ventilation performance by verifying numerical simulation through model tests.By analyzing the impacts of installation angle,dimension,location,and quantity of opening baffle on ventilation performance,the paper reached the conclusions as follows:1)When installation angle is larger than 45°and tunnel ventilation is well operated,the baffle exhaust could increase by at least 30%compared to when there is no baffle.2)The baffle reaches its optimal performance when the length of the baffle is equal to the width of the city road tunnels.3)Baffle exhaust could increase by 30%when it is installed in the downstream of openings.4)The performance of a single baffle is better than that of multiple baffles.展开更多
Fire is the foremost critical event for road tunnels’ safety. Therefore, the European Commission introduced the Directive 2004/54/EC for enhancing tunnels’ safety since they constitute a key element of the Trans-Eur...Fire is the foremost critical event for road tunnels’ safety. Therefore, the European Commission introduced the Directive 2004/54/EC for enhancing tunnels’ safety since they constitute a key element of the Trans-European Road Network. The Directive has established a common ground for tunnels’ safety evaluation providing certain minimum requirements while introducing officially the use of risk assessment. Despite the signifi-cant progress, this paper illustrates that further efforts are needed. Through a comparative review of the risk assessment methods, questions about the level of harmonisation of the framework are raised. Moreover, considerable problems are highlighted, like the incorporation of the new trends emerging from the literature or the deficiencies on addressing significant issues of the analysis, such as the risk acceptance criteria and the behaviour of trapped-users. These problems can affect the risk assessment process causing both significant discrepancies and deficiencies at the estimated level of tunnels’ safety.Uncovering, thus, the deficiencies and limitations of the methods, this paper contributes to i) the discourse for initiating relevant studies to enhance tunnels’ fire safety in Europe and worldwide, and ii) the harmonisation of risk assessment methods.展开更多
Since opening in 2010, The Carmel Tunnels have redirected some of the traffic from within the City of Haifa in Israel. This paper studies the direct and indirect financial and environmental benefits of the Carmel Tunn...Since opening in 2010, The Carmel Tunnels have redirected some of the traffic from within the City of Haifa in Israel. This paper studies the direct and indirect financial and environmental benefits of the Carmel Tunnels compared to alternative routes. Di-rect benefits for drivers include financial savings thanks to savings on time and gas. Indirect benefits for drivers and for the public include reduced air pollution, green-house gas emissions and noise. Results show significant positive benefits from using the Carmel Tunnels compared to various alternative routes (i.e., reference scenarios). During peak hours (8 am and 4 pm), when there is heavy traffic on the alternative routes, the total benefits increase by about 25% - 47%. Using tunnels for transportation allows, among other benefits, efficient use of underground land, redirecting traffic congestion from town centers, decreasing landscape damage due to major roads passing through open spaces, and reducing air pollution in residential areas.展开更多
基金the Changsha Science and Technology Plan 2004081in part by the Science and Technology Program of Hunan Provincial Department of Transportation 202117in part by the Science and Technology Research and Development Program Project of the China Railway Group Limited 2021-Special-08.
文摘The detection of crack defects on the walls of road tunnels is a crucial step in the process of ensuring travel safetyand performing routine tunnel maintenance. The automatic and accurate detection of cracks on the surface of roadtunnels is the key to improving the maintenance efficiency of road tunnels. Machine vision technology combinedwith a deep neural network model is an effective means to realize the localization and identification of crackdefects on the surface of road tunnels.We propose a complete set of automatic inspection methods for identifyingcracks on the walls of road tunnels as a solution to the problem of difficulty in identifying cracks during manualmaintenance. First, a set of equipment applied to the real-time acquisition of high-definition images of walls inroad tunnels is designed. Images of walls in road tunnels are acquired based on the designed equipment, whereimages containing crack defects are manually identified and selected. Subsequently, the training and validationsets used to construct the crack inspection model are obtained based on the acquired images, whereas the regionscontaining cracks and the pixels of the cracks are finely labeled. After that, a crack area sensing module is designedbased on the proposed you only look once version 7 model combined with coordinate attention mechanism (CAYOLOV7) network to locate the crack regions in the road tunnel surface images. Only subimages containingcracks are acquired and sent to the multiscale semantic segmentation module for extraction of the pixels to whichthe cracks belong based on the DeepLab V3+ network. The precision and recall of the crack region localizationon the surface of a road tunnel based on our proposed method are 82.4% and 93.8%, respectively. Moreover, themean intersection over union (MIoU) and pixel accuracy (PA) values for achieving pixel-level detection accuracyare 76.84% and 78.29%, respectively. The experimental results on the dataset show that our proposed two-stagedetection method outperforms other state-of-the-art models in crack region localization and detection. Based onour proposedmethod, the images captured on the surface of a road tunnel can complete crack detection at a speed often frames/second, and the detection accuracy can reach 0.25 mm, which meets the requirements for maintenanceof an actual project. The designed CA-YOLO V7 network enables precise localization of the area to which a crackbelongs in images acquired under different environmental and lighting conditions in road tunnels. The improvedDeepLab V3+ network based on lightweighting is able to extract crack morphology in a given region more quicklywhile maintaining segmentation accuracy. The established model combines defect localization and segmentationmodels for the first time, realizing pixel-level defect localization and extraction on the surface of road tunnelsin complex environments, and is capable of determining the actual size of cracks based on the physical coordinatesystemafter camera calibration. The trainedmodelhas highaccuracy andcanbe extendedandapplied to embeddedcomputing devices for the assessment and repair of damaged areas in different types of road tunnels.
基金Visiting Scholar Foundation of Key Lab. for the Exploitation of Southwestern Resource & the Environmental Disaster Control Engineering in Chongqing University.
文摘an air cleaner employing pulse induced plasma chemical process to remove dust and carbon monoxide (CO) in road tunnels is presented, which is composed of mainly a precipitator, a reactor, a flow control system, a power supply and a measurement system. Its performances are studied in simulated air conditions. It is found that the rate of dust removal is dependent on the voltage of the pulse power, the distance between the two dust collecting plates of the electrostatic precipitator, the effective length of the precipitator and the air flow rate in the precipitator, and that of CO removal is affected by the voltage and frequency of the super pulse power, the air flow rate in the reactor and the relative humidity of air. Applying such an cleaner of a proper design to the treatment of polluted air at a flow rate of 7 m/s can achieve the rate of dust removal up to 93 % and that of CO removal up to 72.6 %, which efficiently controls the concentrations of CO and dust under allowable limits. It is implied that the proposed air cleaner is a potential solution to air control in road tunnels, and is prominent for its performances and saving the huge cost of longitudinal ventilation tunnel or vertical vent and ventilation facilities.
基金Funded by the Doctoral Foundation of the Ministry of Education of China (2000061115)
文摘Road tunnel excavation often traverses coal strata, which is at risk of firedamp explosion that usually results in disaster. Airtight concrete grouting is popularly used in this kind of tunnel project. Based on the essential theory of mechanics of fluids in porous media, the principle of improving concrete airtight property and its influential factors are investigated. The proportioning tests and monitoring method for airtight concrete are introduced, which is illustrated by a case study applied to the project of the Huayinshan Tunnel. It is proved by engineering practices that the achievement of this research work is beneficial to tunneling project across coal strata.
文摘In the USA,risk-based decision making has not been a common approach to tunnel safety in the past,but this is changing,as concepts such as“equivalency”in the NFPA 502 framework gain acceptance in the USA and elsewhere.In other regions,in particular in Europe,risk assessment techniques have been used for nearly two decades in many jurisdictions as an additional tool to complement the application of prescriptive guidelines and support decisions related to tunnel safety.After some initial difficulties these methods are meanwhile a well-established element of tunnel safety management.There are several tools available which have been practically applied and further developed over years,such as the Austrian tunnel risk model TuRisMo,or the PIARC owned DG-QRAM model.Whereas TuRisMo is a holistic,system-based model,which is best suited to quantify and assess fire risk and associated mitigation measures,DG-QRAM focusses on the risks related to the transport of hazardous materials.Depending on the objectives and the scope of the investigation and the regulatory environment,tunnel risk assessment tools are in use for different purposes,mainly to demonstrate a sufficient level of safety and to decide on and select(additional)risk mitigation measures.The international experience substantiates that the general approach is flexible and that the methods and tools are mature and can be applied for different problems in different environments.First case studies like the risk study on conditions and permissibility of the transport of hazardous materials through the Eisenhower-Johnson-Memorial Tunnel in Colorado demonstrate the applicability of a risk-based concept for decision making in the US-American environment.
文摘After some tragic fire events,Directive 2004/54/EC was issued to ensure a minimum safety level for tunnels belonging to the Trans-European Road Network longer than 500 m.Nowadays,most of the Italian road tunnels are still not in compliance with the minimum safety requirements,thus refurbishment works are often planned.By developing a traffic macro-simulation model,this paper aims at assessing the resilience of an existing twin-tube motorway tunnel when one of its tubes is partially or completely closed due to planned activities.Several scenarios were investigated,also considering the availability or not of an alternative itinerary in the surrounding transportation network.The average vehicles’speed was used as a functionality parameter,while the resilience metrics were the resilience loss,the recovery speed,and the resilience index.The findings showed higher resilience losses for complete closure rather than partial closure of the tube under planned refurbishment works.The implementation of digital technologies,such as variable message signs,might reduce the resilience loss of the tunnel system.This research might represent a reference for tunnel management agencies in the choice of the most appropriate traffic control strategy to improve tunnel resilience in the event of planned activities.
文摘The analysis of the fluid characteristics downstream of a fire source in transportation tunnels is one the most important factor in the emergency response, evacuation, and the rescue service studies. Some crucial parameters can affect the fluid characteristics downstream of the fire. This research develops a statistical analysis on the computational fluid dynamics(CFD) data of the road tunnel fire simulations in order to quantify the significance of tunnel dimensions, inlet air velocity, heat release rate, and the physical fire size(fire perimeter) on the fluid characteristics downstream of the fire source. The selected characteristics of the fluid(response variables) were the average temperature, the average density, the average viscosity, and the average velocity. The prediction of the designed statistical models was assessed; then the significant parameters' effects and the parameters interactive effects on different response variables were determined individually. Next, the effect of computational domain length on the selection of the significant parameters downstream of the fire source was analyzed. In this statistical analysis, the linear models were found to provide the statistically good prediction. The effect of the fire perimeter and the parameters interactive effects on the selected response variables downstream of the fire, were found to be insignificant.
基金Doctoral Funds of Education Ministry of China(2000061115)
文摘In some cases coal measures,goaf,big caves,and huge faults,as well as high initial stress cannot be avoided in road tunnel excavation.These geological features may make it more difficul practical tunnel construction. So it is necessary to take strong precautious measures against gas outburst,water bursting and roof fall in a tunnel across coal measures with risk of gas outburst.The techniques,such as advance drilling exploration,multiple-cycle shallow depth hole controlled blasting,reinforced supporting,which include concrete grouting and twice supporting,and monitoring measures are often applied in the construction of tunnels and satisfied results are achieved. Results in this paper can help others to get experiences in road tunnel construction with similar geological features.
基金funded by the Science and Technology Project of Department of Communications of Shanxi Province,China(Grant No.2019-JKKJ-59)the Science and Technology Project of Department of Communications of Hebei Province,China(Grant No.TH-201909).
文摘The tunnel pavement is generally made of asphalt or concrete.Due to the relatively fixed material of pavement,the effect of tunnel pavement setting on the lighting environment and visual performance of drivers has not received sufficient attention,especially the impact on the visual performance of drivers during driving has not been revealed.Therefore,experimental research on the visual recognition performance of an obstacle on asphalt and concrete pavements inside tunnels during dynamic driving was conducted in this study.The results indicate that under the same pavement illumination,the luminance on concrete pavement is higher than that on asphalt pavement due to the higher reflectance of concrete.The visible distance of the human eyes for a gray obstacle with a reflectance of 0.2 on the concrete pavement is greater than that on the asphalt pavement,and the visible distance of the obstacle on the concrete pavement increases by more than 28%.When the color of the obstacle and the pavement are close,it can be challenging for observers to recognize the obstacle,and the pavement and obstacle need to have a higher level of luminance for the recognition.During dynamic driving,the visible distance at a speed of 60 km/h is 1.2 to 1.4 times that at a speed of 80 km/h,which means the influence of vehicle speed on the human eye’s recognition of obstacles on asphalt and concrete pavements should be taken into consideration in the design of road tunnel lighting.The correlated color temperature and S/P value of LED light have little impact on the visible distance of human eyes to the obstacle on the asphalt and concrete pavements,but it does create different visual perceptions.As the correlated color temperature and S/P value increase,the lighting environment of the tunnel gradually gives a brighter feeling to drivers.
文摘Road pavements in tunnels are usually made of asphalt mixtures,which,unfortunately,are flammable materials.Hence,this type of pavement could release heat,and more specifically smoke,in the event of a tunnel fire,thereby worsening the environmental conditions for human health.Extensive research has been conducted in recent years to enhance the fire reaction of traditional asphalt mixtures for the road pavements used in tunnels.The addition of the Flame Retardants(FRs)in conventional asphalt mixtures appears to be promising.Nevertheless,the potential effects of the FRs in terms of the reduction in consequences on tunnel users in the event of a large fire do not seem to have been sufficiently investigated by using fluid dynamics analysis as a computational tool.Given this gap of knowledge,this article aims to quantitatively evaluate whether the use of flame-retarded asphalt mixtures,as opposed to traditional ones without FRs,might mitigate the adverse effects on the safety of evacuees and fire brigade by performing numerical analyses in the case of a tunnel fire.To achieve this goal,3D Computational Fluid Dynamics(CFD)models,which were executed using the Fire Dynamics Simulator(FDS)tool,were established in the case of a major fire of a Heavy Goods Vehicle(HGV)characterized by a maximum Heat Release Rate(HRRmax)of 100 MW.The people evacuation process was also simulated,and the Evac tool was used.Compared to the traditional asphalt pavements without FRs,the simulation findings indicated that the addition of the FRs causes a reduction in CO and CO_(2)levels in the tunnel during the aforementioned fire,with a minor number of evacuees being exposed to the risk of incapacity to self-evacuate,as well as certain safety benefits for the operability of the firefighters entering the tunnel downstream of the fire when the tunnel is naturally ventilated.
基金supported by the National Natural Science Foundation of China (Grant No. 10802042)the NaturalScience Foundation of Shandong Province (Grant No.Y2007A04)
文摘In this article,the processes of vans running into a one-way two-lane road tunnel are simulated numerically using the dynamic mesh technique and RNG k ？ ε turbulence model.The transient aerodynamic characteristics around vans are obtained in three cases：a single van,two vans side-by-side and two vans one after another running into the tunnel,respectively.Through a comparison with the results of the wind tunnel experiment,the transient simulation method is verified.The results show that,when a van runs into the tunnel,the aerodynamic drag coefficient increases near the tunnel entrance,and after entering the tunnel,the side force is generated,pointing to the tunnel wall nearer to the van.When two vans run into the tunnel side-by-side,their drag coefficients increase by 50%,and the side force varies sharply with directions changing twice near the tunnel entrance.When two vans run into tunnel one after another,the aerodynamic characteristics around the van in the front is similar to that of a single van,but the aerodynamic forces on the van behind do not have obvious change.Among the three cases,the aerodynamic forces have a sharp change when two vans run side-by-side,so driving side-by-side into a tunnel should be avoided for safety.
基金This research project was supported by the Ministry of Transport of Quebec and the NSERC Discovery Grants[#RGPIN-2018-06734]from Canada5s Natural Sciences and Engineering Research Council.
文摘Road tunnels consume a large amount of energy,especially in the Canadian cold climate,where the roads are heated electrically or deicing during the winter.For a more sustainable and resilient road tunnel energy system,we conducted an exploratory study on installing a semi-transparent photovoltaic(STPV)canopy at the entrances and exits of a tunnel under a river.The proposed system generates solar-powered electricity,improves thermal and visual conditions,and reduces energy loads.In this study,field measurements of road surface temperature and air temperature were conducted,and numerical simulations with and without STPV were performed to study air and road surface temperatures under different traffic speeds.The field measurements show the road surface temperatures are higher than the air temperature on average.The interior air and road surface temperature were measured to be above 0°C,even though the outdoor temperature is far below 0°C,thus significantly reducing the need for deicing in winter using salts.The simulations show that the air and surface temperatures elevate due to the solar transmission heat through the STPV canopy,thus reducing deicing energy consumption significantly.The fire safety analysis also showed that the proposed system's top opening should be located near the tunnel entrance instead of the canopy entrance for better smoke exhaust during a fire.
基金The work of the first author was sponsored by the Shanghai Pujiang Program(No.20PJ1406100)the National Natural Science Foundation of China(Grant No.52208398)+1 种基金In addition,the financial support from the Sino-German Center for Research Promotion,provided within project GZ 1574,is gratefully acknowledged.The last author acknowledges financial support from the Science and Technology Commission of Shanghai Municipality(No.21DZ1203504)the National Natural Science Foundation of China(Grant No.51808336).Moreover,the interesting discussions with Mr.Enjie HU are gratefully acknowledged.
文摘Prefabricated internal structures of road tunnels,consisting of precast elements and the connections between them,provide advantages in terms of quality control and manufacturing costs.However,the limited construction space in tunnels creates challenges for on-site assembly.To identify feasible connecting joints,flexural tests of precast straight beams connected by welding-spliced or lap-spliced reinforcements embedded in normal concrete or ultra-high-performance fiber-reinforced concrete(UHPFRC)are first performed and analyzed.With an improvement in the strength grade of the closure concrete for the lap-spliced joint,the failure of the beam transforms from a brittle splitting mode to a ductile flexural mode.The beam connected by UHPFRC100 with short lap-spliced reinforcements can achieve almost equivalent mechanical performance in terms of the bearing capacity,ductility,and stiffness as the beam connected by normal concrete with welding-spliced reinforcements.This favorable solution is then applied to the connection of neighboring updeck slabs resting on columns in a double-deck tunnel.The applicability is validated by flexural tests of T-shaped joints,which,fail in a ductile fashion dominated by the ultimate bearing capacity of the precast elements,similar to the corresponding straight beam.The utilization of UHPFRC significantly reduces the required lap-splice length of reinforcements owing to its strong bonding strength.
文摘Selecting fires safety measures for road tunnels relies mainly on strict regulatory requirements. However, the choice should also be based on many different criteria and ranking of alternatives should take place. Existing methods exhibit lack in dealing rigorously with measures’ selection amongst different alternatives. This paper contributes to the body of knowledge by proposing a novel method, named EVADE, which aims to incorporate diverse stakeholders’ views and provide a meaningful ranking of alternatives.To do so, it estimates the tunnel level of safety taking into account only any standard measures existing. Subsequently, the performance of additional measures is examined.Then, a list of the most significant criteria that are valuable to judge the appropriateness of selected measures is introduced. The relative importance amongst the decision criteria is calculated through the Analytic Hierarchy Process, based on the expert opinion. Sensitivity analysis through Monte Carlo simulation is embedded to allow for a meaningful prioritization of the decision criteria. Thus, the alternatives’ ranking comes as a distribution instead of a single number, providing the decision-maker richer information for selecting the most suitable measure(s) according to the specific tunnel situation. At last, a typical tunnel is examined to showcase the utilization of the method.
基金This work was supported by the Science and Technology Foundation of Tianjin City,China(10ZCKFSF02300).
文摘Based on the opening baffle mode for natural ventilation of city road tunnels,this paper studies the impacts of opening baffle on natural ventilation performance by verifying numerical simulation through model tests.By analyzing the impacts of installation angle,dimension,location,and quantity of opening baffle on ventilation performance,the paper reached the conclusions as follows:1)When installation angle is larger than 45°and tunnel ventilation is well operated,the baffle exhaust could increase by at least 30%compared to when there is no baffle.2)The baffle reaches its optimal performance when the length of the baffle is equal to the width of the city road tunnels.3)Baffle exhaust could increase by 30%when it is installed in the downstream of openings.4)The performance of a single baffle is better than that of multiple baffles.
文摘Fire is the foremost critical event for road tunnels’ safety. Therefore, the European Commission introduced the Directive 2004/54/EC for enhancing tunnels’ safety since they constitute a key element of the Trans-European Road Network. The Directive has established a common ground for tunnels’ safety evaluation providing certain minimum requirements while introducing officially the use of risk assessment. Despite the signifi-cant progress, this paper illustrates that further efforts are needed. Through a comparative review of the risk assessment methods, questions about the level of harmonisation of the framework are raised. Moreover, considerable problems are highlighted, like the incorporation of the new trends emerging from the literature or the deficiencies on addressing significant issues of the analysis, such as the risk acceptance criteria and the behaviour of trapped-users. These problems can affect the risk assessment process causing both significant discrepancies and deficiencies at the estimated level of tunnels’ safety.Uncovering, thus, the deficiencies and limitations of the methods, this paper contributes to i) the discourse for initiating relevant studies to enhance tunnels’ fire safety in Europe and worldwide, and ii) the harmonisation of risk assessment methods.
文摘Since opening in 2010, The Carmel Tunnels have redirected some of the traffic from within the City of Haifa in Israel. This paper studies the direct and indirect financial and environmental benefits of the Carmel Tunnels compared to alternative routes. Di-rect benefits for drivers include financial savings thanks to savings on time and gas. Indirect benefits for drivers and for the public include reduced air pollution, green-house gas emissions and noise. Results show significant positive benefits from using the Carmel Tunnels compared to various alternative routes (i.e., reference scenarios). During peak hours (8 am and 4 pm), when there is heavy traffic on the alternative routes, the total benefits increase by about 25% - 47%. Using tunnels for transportation allows, among other benefits, efficient use of underground land, redirecting traffic congestion from town centers, decreasing landscape damage due to major roads passing through open spaces, and reducing air pollution in residential areas.
