With the advancement of highway tunnel mechanized construction, various new technologies and new equipment are gradually introduced into highway tunnel construction, which requires construction units to constantly improve their own highway tunnel mechanized construction level to ensure the improvement of highway tunnel mechanized construction efficiency and quality. Based on this, this paper puts forward the most commonly used highway tunnel mechanized construction technology in our country at the present stage, to realize the digital management of highway tunnel mechanized construction, to ensure the safety and economic benefits of the entire highway tunnel mechanized construction, and to lay a solid foundation for highway tunnel mechanized construction.

The improvement of infrastructure makes the scale of highway tunnel larger and larger. Therefore, improving the efficiency and quality of highway tunnel mechanized construction, improving the construction environment, controlling construction costs and saving construction resources have become the key contents of modern highway tunnel mechanized construction. Traditional construction technology can no longer cope with these problems. This requires the construction unit to promote the smooth progress of highway tunnel construction through advanced mechanized construction technology.

1 Development of highway tunnel mechanized construction technology

1.1 Development of construction methods

With the innovative development of highway tunnel construction technology, the relevant departments have put forward the new Austrian method, Norwegian method and shallow buried excavation method suitable for modern highway tunnel mechanized construction on the basis of summarizing the practical experience of the project, and have been widely used in the mechanized construction of highway tunnel, ensuring that the mechanized construction of highway tunnel has achieved good results. It comprehensively improves the safety and construction efficiency of highway tunnel mechanization construction.

1.2 Development of construction equipment

In order to ensure the effectiveness of the construction process, it is necessary to support the construction equipment as the premise. In the process of innovation of highway tunnel mechanized construction equipment, TBM boring machines, rock drilling trucks and shield tunneling machines have begun to practice for different geological conditions of rock formations, comprehensively improving the efficiency of highway tunnel mechanized construction and enhancing the quality of highway tunnel mechanized construction. And through the research and development of full hydraulic drilling trolley, hydraulic lining trolley and large loading machinery, the driving speed and construction efficiency of highway tunnel engineering are enhanced, and the working environment of highway tunnel mechanization construction is effectively improved.

2 Highway tunnel mechanized construction preparation and management

2.1 Preparation of mechanized construction sites and equipment for highway tunnels

In the construction process of highway tunnel engineering, it is necessary to clarify the site layout of the mixing station to ensure the clarity of various functions, on the basis of the original site area, to ensure that the number of raw material warehouse can meet the corresponding production needs, ensure the complete identification and signage, and strengthen the standardization and order of raw material stacking. For the mechanized construction of highway tunnel, it is not only necessary to have advanced construction machinery and equipment, but also to have sufficient construction space and install appropriate hydropower devices to ensure the smooth progress of public tunnel construction.

2.2 Management of Highway tunnel mechanized construction process

(1) Precautions for highway tunnel excavation. The construction unit needs to formulate a perfect construction plan before the mechanized construction of the highway tunnel, and actively promote the concept of zero excavation of highway tunnel construction, so as to avoid damage to the mountain during the excavation process, so that the mountain can maintain the original ecological environment and landform. If the surrounding rock of the entrance of the highway tunnel construction site does not have good construction conditions, the construction personnel need to adjust the sequence of highway tunnel mechanization construction in time, and strictly follow the basic principle of opening the tunnel first and then hiding the hole in the actual construction, and the greening project construction procedure can be started 50m after the secondary lining of the highway tunnel.

(2) Management of entrance of highway tunnel during mechanized construction. In the process of mechanized construction of highway tunnel, the management of the entrance needs to be in strict accordance with the requirements of mechanized construction, install the access control system with face recognition, and do a good job of the comprehensive supervision and management of the environment in the tunnel and the construction personnel. In addition, the construction unit also needs to install early warning and alarm system, emergency communication equipment and human-vehicle diversion facilities in the highway tunnel to strengthen the safety of the environment in the highway tunnel. The construction unit also needs to set up a highway tunnel entrance management duty team, install signal warning lights, and build a fixed duty room at the entrance, by the duty personnel to inspect the traffic and personnel passing through the highway tunnel entrance, and by the duty personnel to guard the tunnel blasting warning light.

3 Highway tunnel mechanized construction technology

3.1 Full computer multi-arm drilling rig drilling instead of manual drilling

For the mechanized construction of highway tunnel, at this stage, many construction units often use the full-computerized multi-arm drilling rig to drill instead of the traditional manual drilling operation. This full-computerized multi-arm drilling rig drilling equipment has high frequency impact and accurate blasting degree, and the construction personnel need to coordinate the ultra-high impact energy when using the drilling equipment. Comprehensively improve the drilling speed and efficiency of the drilling rig, and minimize over and under digging. If highway tunnel construction personnel in the process of drilling operations, the use of full computer multi-arm drilling truck drilling operations, it is enough to exceed the speed of traditional multi-person drilling operations. The use of drilling rig can effectively reduce the number of manual workers, improve the efficiency and quality of drilling operations, and effectively shorten the cycle operation time in the mechanized construction of highway tunnels, reducing the probability of manual operation casualties.

3.2 Arch work trolley and charge truck instead of trolley work

The arch work trolley and charging vehicle mainly play the role of charging, erecting and hanging the net in the mechanized construction process of highway tunnel, which has the characteristics of relatively stable performance and good operability. The trolley mainly includes the trolley body, the lifting shell, the bottom wheel seat and so on. During the actual use of the trolley, the installation and disassembly of the wheels are very simple, and the transportation of tools and materials is also faster; The use of the charging vehicle can not only achieve a good match with the tunnel project, but also realize the automatic movement trajectory movement through the intelligent mechanical pipe feeding device and positioning system, so as to realize the intelligent unmanned operation of the loading and unloading. Therefore, compared with the traditional tools, such as the arch working trolley and the charging truck, it can effectively reduce the operation space and the number of operators, and can better assist the construction of highway tunnels.

3.3 Spray film waterproof instead of traditional waterproof board

In the process of highway tunnel construction, the problem of leakage has become a common quality problem, especially at the present stage in our country, many highway tunnels in the actual construction process, the composite lining waterproof operation mostly uses waterproof coil, although this waterproof coil is cost-effective, but the actual use effect has not reached the expected value. In recent years, some experts and scholars began to study the tunnel film waterproofing technology and applied it to the highway tunnel mechanized construction. In the practical application of strong adhesive tunnel film spraying waterproof technology, synthetic latex is mainly used as the main material of spray forming film, and its auxiliary material is thermoplastic rubber modified emulsified asphalt. These two materials can make the surface of the staff in the process of spraying process, so as to realize the seamless waterproof of the overall structure of the special-shaped structure.

Generally speaking, the thickness of the strong adhesive tunnel film spraying waterproof technology is mainly 0.1-0.4cm, and it can be formed at one time, which has the characteristics of saving time, saving labor and strong uniformity in the actual use process, and can effectively adapt to the diverse needs of the highway tunnel mechanized construction site. In addition, the requirements of highway tunnel mechanization construction conditions are relatively broad, there is no harsh construction conditions, and the film spraying waterproof technology of strong adhesion tunnel can be applied to various special-shaped bases. In addition, in the practical application of the film spraying waterproof technology of the tunnel with strong adhesion, it is necessary to suspend the application of the film spraying waterproof technology of the tunnel with strong adhesion if the problem of bad winter weather affects the smooth construction of the highway tunnel is encountered.

3.4 Carbon dioxide blasting instead of explosive blasting

In the mechanized construction process of highway tunnel, the use of post-carbon dioxide blasting instead of explosive blasting is mainly to use the heat absorption effect of liquid carbon dioxide, so that it can expand rapidly, and the pressure is also rapidly increased, and then the surrounding rock of the highway tunnel construction site is broken, so as to avoid the shortcomings of high vibration, high danger and more effective gas caused by traditional explosive blasting. For the actual operation of construction personnel to create a strong safety, high degree of environmental protection and more economic characteristics, and then play a role in protecting the surrounding rock and improving the construction environment of highway tunnel engineering.

3.5 Application of wet spray machine truck

Traditional highway tunnel construction mainly adopts manual dry spraying or tidal shotcrete operation methods. The application of these two methods makes the dust in the highway tunnel too large, which is not conducive to the formation of a good working environment in the highway tunnel, and even easy to fill part of the fill when the overdigging is large, thus forming a hollow situation, which directly affects the overall service life of the tunnel. In addition, the water consumption control degree of manual dry shotcrete is not accurate enough to effectively ensure the strength of concrete. In general, the use of traditional dry spraying methods mainly take the spray machine is a small spray machine, the power of the spray machine is relatively small, the duration of the spray is relatively long, if the construction personnel are exposed to this spray environment for a long time, it is prone to pneumoconiosis and silicosis and other occupational diseases. When the construction personnel use the wet spray truck, the mixing work is mainly carried out by the concrete mixing station, and it is transported to the designated location by the tank truck. This method not only effectively reduces the dust content in the operation, but also improves the injection efficiency and quality, and can effectively reduce the working time of the construction personnel in the highway tunnel. The probability of occupational disease for construction workers is reduced.

3.6 Invert hydraulic trestle

In the process of highway tunnel invert construction, the traditional invert construction technology mainly adopts the split construction method or the self-made invert trestle method. The application of these two methods in the mechanized construction of highway tunnel is easy to cause the filled concrete to enter the second lining, which directly leads to a very weak link at the arch foot of highway tunnel. In addition, the self-made invert trestle in the mechanized construction of highway tunnel is mainly formed according to the construction personnel's own experience, without scientific and systematic force calculation, not only the safety factor is relatively low, but also the movement of invert trestle mainly depends on the drags of excavators or loaders. In the process of mechanized highway tunnel construction by using self-propelled hydraulic trestle supporting invert formwork, the automatic hydraulic invert trestle can drive itself through crawlers, and the hydraulic system can adjust and optimize the formwork to strengthen its walking flexibility and ensure the convenience of hydraulic invert trestle construction.

3.7 Waterproof board mounted trolley

For the mechanized construction of highway tunnel, the hanging of the traditional process waterproof board requires the construction personnel to first lay the process waterproof board on the road tunnel wall, and the process waterproof board laying requires at least three construction personnel according to the different construction area, coupled with the waterproof board construction and laying labor intensity is relatively large, making the process waterproof board difficult to control the tightness during the laying process. In addition, the construction unit adopts the waterproof plate automatic hanging trolley equipment in the mechanization construction of highway tunnel, which can make full use of its own arc track system and traction system, and move the car with waterproof plate from the bottom to the bottom of the other side, so that it can automatically unfold the waterproof plate, and fix the waterproof plate while reducing the labor intensity of the construction personnel. Thus effectively adjust the tightness of the waterproof plate hanging.

3.8 Cable Trench Trolley

The highway tunnel mechanization construction needs to adopt the method of cable trench trolley walking in place to ensure that the construction personnel can use the hydraulic system to carry out the overall control of the highway tunnel internal template and move in place, which saves the time of manual template splicing, shortens the construction around the entire highway tunnel project, and the labor intensity and pressure of the construction personnel are also reduced. This kind of mobile mold frame is not only fast to install, but also convenient to remove, and can be reused in construction, effectively reducing the cost of highway tunnel mechanization construction. In the mechanized construction process of highway tunnel, the concrete pouring work mainly uses the attached vibrator to prevent the randomness of manual vibration work, and effectively avoids the phenomenon of sand flow and honeycomb surface in the concrete pouring process.

4 Digital management mode of Highway tunnel mechanized construction

4.1 Video surveillance

In the process of highway tunnel mechanized construction, it is also necessary to establish a perfect tunnel surveillance video system, so as to achieve comprehensive coverage of the entire highway tunnel construction management space, and focus on management according to climate temperature and construction categories. Generally speaking, the application of video surveillance system in the mechanization construction of highway tunnel can strengthen the construction unit's dynamic grasp of the number of workers, working time, ventilation and other information on the tunnel face, which means that the construction unit on the basis of information management, to establish a perfect Internet of Things system of highway tunnel mechanized construction equipment collaborative remote scheduling system. After the application of video surveillance in highway tunnel mechanized construction, the development of highway tunnel mechanized construction can strengthen the integration between various elements, strengthen the remote control between various elements, ensure the coordination between various elements, and promote the smooth development of highway tunnel mechanized construction.

4.2 Personnel positioning and Remote control system

The application of BIM technology in the mechanized construction of highway tunnel can not only realize the accurate positioning of personnel and design entering the tunnel, but also accurately control the number of personnel and equipment entering the tunnel when unexpected situations occur. The application of the above video surveillance in the highway tunnel can not only realize the monitoring function, but also realize the remote control function, which can be combined with the remote control platform set inside the tunnel, and can truly realize the remote wireless control of large mechanical equipment such as air compressors, axial flow fans and jet fans inside the highway tunnel.

5 Conclusion

To sum up, in order to ensure the quality and effect of highway tunnel mechanized construction, it is necessary to strengthen the preparation and management of highway tunnel mechanized construction, through the full computer multi-arm drilling rig instead of manual drilling, arch work rig and charging truck instead of truck operation, spray film waterproof instead of traditional waterproof plate, carbon dioxide blasting instead of explosive blasting. Strengthen the application quality of wet spray mechanical trolley, and speed up the construction process of highway tunnel project through the construction technology of invert hydraulic trestle, waterproof plate hanging trolley and cable trench trolley, which can effectively solve the problems of tunneling speed and low construction efficiency in the current mechanization construction of highway tunnel, and ensure the safety of highway tunnel mechanization construction. Then improve the working conditions of highway tunnel mechanization construction, and promote the smooth and effective development of highway tunnel mechanization construction.