Environmental characteristics of 1. 1
Highway tunnel is a special structure of highway. Due to the limitation of space, the environmental conditions in the tunnel have the following characteristics:
1) The harmful exhaust gas of mixed gas and free solid particles emitted by driving vehicles, the dust carried by vehicles and the rolled-up dust often cannot spread and disappear quickly due to the space limitation in the tunnel;
2) Because of the abundant trickle in the mountains and the large temperature difference between inside and outside the tunnel, the tunnel is often in a very humid environment;
3) Because the secondary lining of the tunnel and the road surface in the tunnel are rigid bodies, when heavy vehicles pass through the tunnel, the vibration in the tunnel is large;
4) Due to the busy traffic, harsh environment and limited space in the tunnel, the daily maintenance and troubleshooting of equipment are difficult, and the labor intensity is high and the effect is poor.
1.2 Characteristics of operation and management facilities of highway tunnels
The operation and management facilities of long highway tunnels have the following characteristics:
1) There are many kinds of facilities, including tunnel lighting system, tunnel ventilation system, tunnel fire extinguishing system, automatic fire detection and manual alarm system, emergency telephone system, tunnel wireless dispatching intercom system, tunnel wireless broadcasting system, tunnel closed-circuit television monitoring system, traffic parameter detection and traffic control and signal providing system, tunnel environmental parameter detection and ventilation, lighting control system and power supply and distribution system.
2) Many subsystems have a large number of devices, such as lighting lamps, automatic fire detectors, cameras and alarm buttons.
3) High equipment price, large investment and heavy workload of operation and maintenance, such as visibility meter, illuminance meter, ventilation and lighting system, etc.
4) Many special equipment have no mature products in China and need to be imported.
To sum up, from the particularity of highway tunnel itself and the characteristics of tunnel operation management system, it can be seen that the design, setting and system configuration of tunnel operation management facilities are more complicated and demanding than the traffic monitoring system on the road section. Therefore, in the design process of tunnel operation management system, it is necessary to compare the configuration of subsystems and equipment from the aspects of practicality, economy, reliability and maintainability, and analyze their functions, functions, use effects, convenience of operation and maintenance, as well as their investment and operating expenses, according to the civil scale, phased implementation plan and investment situation of the tunnel, as well as the traffic volume and traffic volume growth predicted in the early stage, so as to determine the scale, system configuration and equipment number of the operation management system.
When designing the overall scheme of the tunnel operation management system, we should seriously consider the complementarity of the functions of each subsystem, analyze their overlapping functions, and handle the relationship between the practical reliability of the system in the early stage of the project and the integrity and advancement of the system in the later stage, so as to make the tunnel operation management system conform to the level of China's economic development in terms of investment cost and economic benefits, and not exceed the affordability of the owners. In terms of technical functions, it can take into account the needs of early management and is suitable for future upgrading and expansion.
2. Analysis of each subsystem of operation management system
2. 1 Tunnel lighting and its control system
In order to avoid the "black hole" and "white hole" effects when vehicles drive into and out of the tunnel at high speed and ensure the safety of vehicles in the tunnel, according to the Code for Design of Highway Tunnels, daytime lighting facilities should be installed in highway tunnels with the length exceeding1000 mm. The lighting design of highway tunnels, the division of lighting sections, the length of each lighting section and the minimum brightness of the road surface are all detailed in the Code for Design of Highway Tunnels. The lighting source shall be high-pressure sodium lamp, low-pressure sodium lamp or fluorescent lamp. In order to achieve the brightness required for safe driving in the tunnel, a considerable number of lighting lamps need to be configured. However, in the process of tunnel operation, lighting equipment takes a long time and consumes a lot of electricity, which accounts for a large proportion of tunnel operation cost. Therefore, a key problem in the design of highway tunnel lighting system is the selection, configuration and control of lighting lamps.
(1) lighting source
The selection and configuration of lighting sources and the reasonable control of lighting system play an important role in ensuring tunnel traffic safety, improving driving comfort, reducing operating costs and reducing maintenance workload. High-pressure sodium lamp and low-pressure sodium lamp have high light efficiency. The high-pressure sodium lamp is about 90 ~ l00lm/w, and the low-sodium lamp can reach more than 140lm/W, with strong fog permeability. However, the low-pressure sodium lamp emits monochromatic yellow light when working, and the high-pressure sodium lamp emits golden white light when working. One of the same disadvantages of both is poor color rendering. The color rendering index is only 25 ~ 40. These two kinds of light sources are used for tunnel lighting, which can only meet the requirements of tunnel rigidity. The purpose of observing and seeing clearly the obstacles on the road is to reflect the authenticity of the tunnel environment and improve the rigidity of the highway tunnel. The comfort of the car, these two light sources are not ideal.
Therefore, in order to better improve the lighting effect of highway tunnel lighting system, we can consider adopting new lighting sources, such as single lamp mixed light. The light mixing effect, light efficiency, color rendering and energy saving of a single mixed-light lamp are better than those of a double-light mixed-light lamp, and the use and maintenance of a single-light mixed-light lamp are also simpler and more convenient than those of a double-light mixed-light lamp. In addition, the medium sodium metal halide lamp has higher luminous efficiency and color rendering index, and will have better lighting effect when used in tunnels, and can obtain good lighting effect and lower lighting cost, but its price is more expensive.
(2) Lighting control
The lighting control in the tunnel is to control the switches of each lighting circuit according to the lighting section determined in the tunnel lighting design and the lighting requirements under different climatic conditions, so as to meet the lighting brightness requirements of the tunnel, ensure driving safety and save energy. Its control modes can be roughly divided into three types: manual control mode, time sequence control mode carried out in different periods, and full-automatic control mode which automatically controls the lighting circuit according to the brightness values inside and outside the cave. Manual control mode is mainly used in tunnel lighting system with low highway grade, short tunnel length and less lighting grade, and different lighting distribution circuits are manually switched according to different time periods and weather conditions.
The subsection time sequence control method is to control each distribution circuit of tunnel lighting with a time sequence controller, and open (close) the corresponding lighting circuit according to different time periods of the day. This control mode is also mainly used for short tunnels and medium-long tunnels with few lighting circuits. The automatic control method of tunnel lighting is to collect the brightness parameters inside and outside the tunnel by using the illuminance meter. After comparison, the computer system or lighting controller automatically controls the switch of each lighting circuit to make the lighting brightness in the tunnel adapt to the brightness of external natural light.
2.2 Tunnel ventilation and its control system
(1) Ventilation facilities
Ventilation and dust removal facilities include fans and electrostatic precipitators. Ventilation modes include vertical, horizontal and semi-horizontal modes. The longitudinal ventilation mode of jet fan can meet the requirements of tunnel operation safety for medium and long tunnel ventilation. The ventilation requirements of extra-long highway tunnels can also be met by adopting the longitudinal ventilation mode of vertical (inclined) shaft with intermediate ventilation or installing electrostatic precipitator. But transverse ventilation or semi-transverse ventilation is rarely used.
The main function of electrostatic precipitator is to remove the smoke in polluted air, and its application can reduce the ventilation required to discharge the smoke generated by a large number of diesel vehicles in the tunnel. The device is not suitable for dusty places on the road surface, and there are a lot of dust and traffic dust carried by cars in the field highway tunnels, because in such tunnel environment, the effect of electrostatic precipitator will be greatly affected, and the cleaning and maintenance of equipment will be greatly increased.
(2) Ventilation control
Ventilation control is based on the allowable concentration of co and the allowable range of smoke permeability, and the control methods are divided into manual control and automatic control. Manual control mode is to manually turn on and off the fans by observing the detected parameters such as traffic flow and co concentration, which is mainly used in highway tunnels with low highway grade, short tunnel length and few fans. Due to the long tunnel length, large traffic volume and large number of fans, the ventilation control mode of the long highway tunnel in expressway is generally fully automatic. Through the co and visibility detector installed in the tunnel, it can detect the co concentration and visibility value in the tunnel in real time, and scientifically and reasonably control the start and stop of the fan according to the ventilation control model and control process determined in advance, which can not only ensure the air environment quality in the tunnel, but also save a lot of energy and operating costs.
2.3 tunnel fire extinguishing system
The fire extinguishing system is to ensure that when a fire is caused by a traffic accident or vehicle failure, the fire can be effectively put out immediately, so as to reduce casualties and property losses and prevent greater damage and serious consequences to the tunnel itself. The Code for Design of Highway Tunnels stipulates that high-grade highway tunnels over 500 meters need to be equipped with fire-fighting equipment rooms, and long highway tunnels need to be equipped with emergency facilities such as alarm and fire fighting. Fire fighting equipment holes are set up every 50 meters to store fire fighting equipment such as fire extinguishers, hoses and sand buckets, and fire hydrants are set up. Therefore, it is necessary to lay fire water supply pipes and fire pools connecting all fire hydrants along the whole tunnel.
(1) There are not many flammable substances in the tunnel itself, and the fires that occur are often caused by traffic accidents or vehicle failures. The location and position of this kind of fire are seriously divided and uneven. This locality and inhomogeneity seriously limit the function of automatic sprinkler system.
(2) Using automatic sprinkler system will not only increase investment, but also increase a lot of management and maintenance work to ensure its integrity and reliability, so the investment-benefit ratio is not high.
(3) Automatic sprinkler system needs to combine automatic fire alarm system and automatic fire extinguishing system into a linkage control system to give full play to its advantages of automatic and rapid fire extinguishing. The design of fire alarm and fire extinguishing linkage control system is a work with strong legal and policy requirements and complex technology. At present, all kinds of automatic fire detection systems at home and abroad cannot directly start the automatic fire fighting system in terms of reliability and accuracy, and it is necessary to confirm the fire accident with the help of closed-circuit television and other equipment. Otherwise, if the automatic sprinkler system in the tunnel breaks down, it will not only fail to fully play its role, but also may hinder the normal driving of vehicles and induce traffic accidents.
Therefore, in the design work, we should pay attention to not simply pursuing the advanced nature of fire fighting technology, but also emphasizing its reliability and safety. At the same time, according to the frequency and characteristics of highway tunnel fires, the maintenance level, convenience and economy are considered. Various chemical fire extinguishing devices, fixed fire hydrants, hoses and full-time firefighters in tunnel management can completely meet the fire protection standard of 15min adopted in China.
2.4 Manual alarm button, automatic fire detection system and emergency telephone system.
At present, various point fire detectors developed and produced by many domestic manufacturers and widely used in many civil buildings are difficult to meet the use requirements in highway tunnels in terms of environmental adaptability, reliability, maintainability and detection area. And due to the limitation of the detection area of each fire detector, hundreds of fire detectors need to be installed in the extra-long tunnel, which brings great inconvenience to daily maintenance and normal work. For long highway tunnels that really need automatic fire detection system, cable fire detectors suitable for tunnel environment can be adopted. However, special attention should be paid to the reliability and stability of detectors and other components in the harsh environment of tunnels. If there is no automatic fire detection system in the tunnel, you can rely on the manual alarm button and emergency telephone system to report fire accidents and abnormal situations to the tunnel management control room.
The emergency telephone system has mature technology, stable and reliable equipment, simple maintenance and convenient use. As an alarm facility for abnormal situations, its accuracy, reliability and utilization rate are the highest among several types of alarm equipment. Therefore, if the density of emergency telephone is properly increased in highway tunnel, the convenience and immediacy of abnormal alarm in tunnel can be greatly improved without additional investment. Because the capacity of ordinary emergency telephone system has a large margin for highway tunnels, there is no need to increase the host capacity of emergency telephone system and the number of transmission cables. As long as the input of emergency telephone is increased, it will facilitate alarm, shorten alarm time, accurately report the type and nature of accidents, facilitate timely and effective rescue and reduce accident losses.
The above briefly introduces the characteristics of the long highway tunnel operation management system, and analyzes the composition, function, role and setting principle of each subsystem, as well as its applicability and reliability. It has certain guiding significance for the design of operation management system of long highway tunnel. However, in the design process, it is necessary to optimize the combination according to the tunnel length, predicted traffic volume, traffic volume composition, investment cost and other specific conditions, ensure the key points, and fully analyze the investment benefits in line with the principles of practicality, reliability, advanced and economy, so that the investment benefits and operational benefits of the long highway tunnel operation management system can be better reflected.
For information about construction enterprises, award-winning achievements, builders under construction, enterprise honors, industrial and commercial information, legal proceedings, etc., please visit Zhong Da Consulting, Construction Link or follow the official account of Zhong Da Consulting WeChat for inquiry.
For more information about project/service/procurement bidding, and to improve the winning rate, please click on the bottom of official website Customer Service for free consultation:/#/? source=bdzd