Queershan tunnel opened to traffic.

1, Queershan tunnel construction process 2, how to evaluate Queershan tunnel crossing Sichuan-Tibet first risk 3, a stalk of Sichuan-Tibet northern line! What are the difficulties in the construction of Queershan Tunnel? Construction Process of Queershan Tunnel

On 20 11June1day, the east entrance approach of Queershan Tunnel on 3 17 National Highway broke ground in Manigango Township, dege county. According to the relevant person in charge of the reconstruction and expansion of Ganzi section of National Highway 3 17 and Queershan Tunnel Construction Command, this approach road is the preliminary project of Queershan Tunnel, and the engineers of Queershan Tunnel can report it and are waiting for the approval of the National Development and Reform Commission. "Now all the preparations are ready, and the engineers will start construction as soon as they come down." According to reports, the length of the approach road at the east entrance of Queershan Tunnel is 14.06 km, designed according to the second-class highway standard, and the pavement width is 8.5 meters. The Queershan Tunnel connected with it is about 7 kilometers long and has a design elevation of 4,240 to 4,380 meters. It is the world's first super-long highway tunnel with an altitude of over 4,300 meters. "Queershan Tunnel is the tallest tunnel in the world, and it is very difficult to build." The relevant person in charge of the project construction headquarters said that Queershan Tunnel will open up a new golden passage in the road trip in western Sichuan.

By September 20 14, the main tunnel of Queershan Tunnel on National Highway 3 17, which was built by China Railway No.1 Bureau and No.4 Company, was excavated 1720 meters, and the horizontal guide broke through the 2000-meter mark, which achieved a staged victory in the node construction period.

At 0 15 12 10 in the morning, the main tunnel at the west entrance of Queershan Tunnel, the world's first high-altitude extra-long highway tunnel, was excavated to the boundary mileage, marking the successful completion of the excavation task at the west entrance of Queershan Tunnel.

The excavation of the west exit of Queershan Tunnel (Q2 Bid Section) was successfully completed.

Queershan Tunnel is 7079 meters long and built on the snowy plateau at an altitude of 4300 meters. It is necessary to overcome the rare construction problems in the world, such as frozen soil, water inrush, fault, rockburst and ventilation support. The construction task of 3530m horizontal guide and subgrade 1200m of main tunnel in Q2 section of Queershan Tunnel shall be undertaken by China Railway No.1 Bureau. After more than three years, the main tunnel has reached the boundary mileage, and the subgrade has been completed recently.

It is understood that China Railway No.1 Bureau is stepping up the construction of inverted arch, second lining and trench cable trough. At the same time, the bureau will set up a construction team to continue horizontal guidance, refit and maintain mechanical equipment, replace cables, ensure ventilation and water supply, formulate construction plans, and make personnel, machinery and technical preparations for double-hole continuous excavation.

How to evaluate the first risk of Queershan tunnel crossing Sichuan and Tibet

The Queer Mountain Tunnel was completed and opened to traffic on September 26th, 2007, and the traffic connecting Ganzi County and dege county is smoother, with few vehicles passing through the Queer Mountain Pass, making Sichuan and Tibet the first risk. Since then, "crossing Queer Mountain in winter is like hitting the gate of hell" has become history.

Note: I made a special trip to Queershan Tunnel on National Day this year.

A stalk on the northern Sichuan-Tibet line! What are the difficulties in the construction of Queershan Tunnel?

Queer Mountain, a mountain that Shan Ying can't fly.

It is the highest highway pass in Sichuan. Winter is covered with snow and ice, and the extreme temperature is below 40℃. Natural disasters such as avalanches, mudslides and collapses are serious, and traffic is often interrupted by snow. There is an average of 7 months of snowfall every year, and the deepest snow can reach 3 meters!

On the Sichuan-Tibet line, Queer Mountain is always a topic in the minds of drivers in the past, and it is the stalk of the northern section of the Sichuan-Tibet line.

The northern line of Sichuan-Tibet line starts from Chengdu, and the main load-bearing section is National Highway 3 17, which passes through Marcand, Luhuo, Ganzi, Dege, Jiangda, Qamdo, Leiwuqi, Dingqing, Baqing and Suoxian, reaches Naqu, joins National Highway 109, and reaches Lhasa, becoming the Dabei Line. Among them, in Luhuo, you can take the provincial road to Kangding xinduqiao and Changdu, and you can reach Bangda. Other sections overlap with national highway 3 18, which is called Sichuan-Tibet Xiaobei Line.

Therefore, no matter how you go, Queer Mountain on National Highway 3 17 will always be a natural barrier. Whether you go or not, the mountain is there, not near, not far.

On September 26th, 20 17, Queershan Tunnel was officially opened to traffic, marking that the national highway 3 17 has become history for many years. Queer Mountain, with an altitude of 6 168 meters and a mountain pass with an altitude of 5050 meters, was once the first risk in Sichuan and Tibet.

China Railway No.1 Bureau undertook the construction of the tunnel exit section with the starting and ending pile numbers K344+500-K349+200, with a total length of 4.726 kilometers. You have to climb Queer Mountain and fight from the inside out.

China Construction Fifth Bureau undertakes the construction task of the tunnel entrance section, with the starting and ending pile number K340+240-K344+500 and the total length of 4.23 1 km, and starts from Manigango to the inside.

What's the difficulty?

The technical problems such as frozen soil, water inrush, fault, rockburst, ventilation and oxygen supply in the construction of extra-long highway tunnels in high altitude areas have been overcome.

Garze Dege Queer Mountain is located in the north line of National Highway 3 17 Sichuan-Tibet Highway, with the main peak at an altitude of 6 168 meters. Every year, it is covered with snow for up to 8 months, and it is called "the first risk in Sichuan and Tibet" because of mountain danger, cold and lack of oxygen. In order to further open the Sichuan-Tibet traffic artery, Queershan Tunnel has gone through a whole 15 years from the start-up scheme demonstration to the completion and opening to traffic.

Queershan Tunnel is located in National Highway 3 17 (between Ganzi and Dege Gangtuo on the northern line of Sichuan-Tibet Highway), about 900 kilometers from Chengdu in the east and 0/50 kilometers from Tibet/KLOC-0 in the west, with a total length of 7079 meters. It is the key control project of National Highway 3 17, and it is also a rare high-altitude extra-long highway tunnel in the world.

The total length of the tunnel is12.995km, and the entrance is 4378m above sea level. It is the longest highway tunnel with the highest altitude in the world. The length of the tunnel is 7.079 km, and the length of approach roads at both ends is 5.9 16 km; The tunnel has a clear width of 9 meters and a clear height of 5 meters, with two lanes in both directions. It adopts the second-class highway standard, with a design speed of 40 kilometers per hour and a total investment of 1, 65,438+0.5 billion yuan. Scheme demonstration and feasibility study began in 2002, construction started in September 20 12, and it was officially opened to traffic on September 26/20 17.

The construction of Queershan Tunnel not only overcomes the difficulties of cold and lack of oxygen, lack of materials and manpower, but also solves the construction problems caused by uncertain factors such as collapse, water inrush and rock burst caused by complex geological conditions in the tunnel area. After five years of fighting, more than 2000 people participated in the construction, and finally this extremely difficult tunnel was built.

Mountain high road danger: "Crossing Queer Mountain in winter is like crossing the gate of hell."

The main peak of Queer Mountain is 6 168 meters above sea level, which is desolate all year round and chilly. Because of the high altitude, even passengers passing through Queer Mountain will have altitude sickness, let alone "stationed" construction workers.

Queer Mountain is the main passage of National Highway 3 17 from the mainland to Tibet. The highest point of Queershan Highway is 5050 meters above sea level, and the road was closed for half a year due to ice and snow. The road conditions are very poor, and it is common to accidentally fall into the ice hole, not to mention falling off the cliff because of the slippery road. It stands to reason that under normal circumstances, a bus leaves at 6 am, and the 589-kilometer journey can arrive at 5 pm. But accidents often happen here, and the bus is delayed until 3 o'clock the next day to reach its destination.

Therefore, Queer Mountain is known as "the first risk in Sichuan and Tibet", and there is a saying in the local area that "crossing Queer Mountain in winter is like crossing the gate of hell".

The lowest temperature here is MINUS 20 degrees Celsius, the humidity is only 40%, the ultraviolet intensity is 3-4 times that of the plain area, and the artificial efficiency is less than half that of the plain area.

The temperature difference inside and outside the cave can reach 70 degrees.

There is a jingle among the workers: "The wind blows the stone and runs away, the grass is not long in four seasons, one breathes three times at a time, and one wears a cotton-padded jacket in summer", which is a vivid portrayal of the climate in Queer Mountain. In extreme weather, the outdoor temperature of the entrance can reach MINUS 40 degrees, which is extremely cold, which is also a major dilemma faced by Queershan tunnel construction.

In winter, due to the work done by mechanical equipment, the temperature in the tunnel can reach more than 30 degrees, forming a temperature difference of nearly 70 degrees with the outdoor, which can be said to be "ice and fire". In particular, concrete can't meet the construction standards in low temperature environment, and occasionally there will be similar "floor heating" equipment under the equipment for storing concrete, keeping the material at about 20 degrees.

Lack of materials and manpower, logistics materials "can't keep up"

During the construction of the project, many materials need to be purchased from Chengdu, which is more than 900 kilometers away. On the way, I have to climb many mountains above 4000 meters above sea level, and most of them are construction sections, and the traffic conditions are extremely poor. Bad traffic conditions directly brought about the shortage of materials and manpower and the difficulty of logistics materials transportation-in the early days, most of the living materials needed by construction workers depended on Chengdu for transportation. Later, the traffic improved and some materials were delivered by Dege.

Five-year construction and five-year route selection exploration-"grinding a sword in ten years"

The route selection of Queershan tunnel is also a big problem-after all, if the altitude is set high, it will not only be easily blocked by snow, but also shorten the distance of the tunnel, which is counterproductive; If the selection is low, it will increase the tunnel length and increase the construction difficulty.

So, engineers personally explored, climbed over Queer Mountain, collected data, and designed several schemes such as 2 km, 4 km and 7 km. Meteorological observation stations are set at the entrances and exits of several pre-selected schemes to observe and record the meteorological element data all year round at different heights, and predict and simulate the actual situation of extreme climate according to the records.

Finally, the design team set the tunnel length as 7 km, and designed the entrance of Queershan Tunnel at an altitude of 4,373 meters and the exit at an altitude of 4,250 meters. The tunnel is high in the middle and low on both sides. This design is mainly to prevent water accumulation in the tunnel and prevent the tunnel from freezing due to water accumulation. Engineers chose the tunnel entrance at the ridge, using natural terrain to avoid avalanches and snow blocking the entrance.

Although the construction period of Queershan Tunnel is five years, it has been used for 10 years since its design, through engineering exploration, geological exploration, meteorological observation and tunnel layout.

Plateau hypoxia

As mentioned above, altitude sickness, the average altitude of Queershan tunnel is more than 4,200 meters, and the oxygen content in the air is equivalent to 58% of that in the plain, while the oxygen content in the deep part of the tunnel is lower than 53% of that in the plain. In order to improve the oxygen concentration in the tunnel, the construction unit has adopted various methods such as setting up oxygen bars, erecting oxygen supply pipes, adding oxygen to ventilation pipes, and carrying oxygen bottles at any time.

However, even if the above measures are taken, it is still not enough insurance. After all, long-term plateau work has a great impact on the health of employees. It started with an annual vacation. However, after physical examination, it was found that many employees' hemoglobin seriously exceeded the standard, so they were adjusted to take a vacation every six months. Moreover, a recreation room and a hot spring bathroom have been built (not far from the tunnel exit, there are hot springs and other ancillary facilities to ensure the physical and mental health of the construction workers.

The altitude sickness of the machine is a bit "scary" and even causes black smoke pollution.

According to experience, every altitude 1000m, the atmospheric pressure drops 10%, the power loss of internal combustion engine drops by 8%- 12%, and the efficiency of pneumatic equipment drops 10%- 13%. In the environment of low air pressure and low temperature, mechanical equipment often encounters difficulties in starting at low temperature. The mechanical efficiency is only about 50-60% of that in plain areas, and the fuel consumption will increase greatly. The efficiency of pneumatic equipment is reduced to half of the original, and the mechanical failure rate is 2-3 times that of plain area.

When the power of mechanical equipment decreases, due to the lack of oxygen in the plateau, the intake oxygen of diesel engine is insufficient, and the diesel oil is not fully combusted after being atomized at _ pressure, resulting in a lot of black smoke polluting the air. The altitude sickness of the machine is even more "scary".

For the problem of black smoke pollution caused by equipment power decline and insufficient diesel combustion, three solutions are adopted:

First, an oxygen pipe is added at the air inlet filter element, so that the oxygen intake of the diesel engine is increased by carrying an oxygen cylinder by the machine, the fuel utilization rate is improved, and the black smoke emission is reduced;

The second is to install a filter device on the exhaust pipe of mechanical equipment to improve the exhaust gas of mechanical equipment;

The third is to add additives to solve the problem of insufficient combustion.

Landslide and water gushing seem to be "routines" in tunnel construction.

Queershan Tunnel passes through the broken zone for many times, and the surrounding rock grade changes greatly alternately-the surrounding rock is granite, but the tunnel passes through four fault zones and belongs to weak surrounding rock, and the construction often encounters disasters such as water inrush, rock burst, landslide and rockburst.

How to avoid landslides?

In order to solve these construction problems, the upper and lower bench method and the reserved core soil method are used to reduce the disturbance to the surrounding rock when excavating the weak surrounding rock of the plateau. In order to avoid the collapse accident and strictly control the excavation step, vibration blasting and loose blasting are adopted to reduce the disturbance to the surrounding rock.

In the cross-section excavation construction, it is necessary not only to ensure that the tunnel clearance and structural size meet the engineering requirements, but also to consider the deformation caused by the initial support. The calculation of reserved deformation should consider many factors such as surrounding rock grade, section size and support, and make reasonable adjustments according to different environments.

When supporting, the weak surrounding rock is anchored by pipe shed and advanced small conduit; Advance small duct grouting to reinforce surrounding rock. Grouting slurry usually adopts pure cement slurry or glass mixed with water to reinforce surrounding rock. When protecting weak surrounding rock, lock-foot anchor is selected for reinforcement. Lock-foot anchor technology is a new structure composed of anchor rod, concrete surface and anchor plate. Before the tunnel excavation, the anchor rod is driven into the arch foot through the arrangement of the lock foot anchor rod, and the weak surrounding rock is protected and strengthened with the anchor plate to form a composite structure. Lock-foot anchor can enhance the bearing capacity and stability of rock mass, make the role of lock-foot anchor play an effective role, and prevent the collapse of weak surrounding rock due to deformation or insufficient bearing capacity.

How to solve the problem of water inrush?

Queershan Tunnel passes through three major fault fracture zones. Near the fault fracture zone and its influence zone, the rock mass is broken, the fractures are developed, the fracture connectivity is good, and the groundwater storage space is large. However, granite between faults has relatively complete rock mass, poor fracture connectivity and relatively water resistance. Therefore, the tunnel site is a series of hydrogeological structures controlled by reticular faults, which are alternately water-bearing and water-resisting.

The construction unit adopted drainage grouting to effectively solve the water gushing problem. Drain the accumulated water in the tunnel through the drainage hole, drainage hole and water pump to reduce the groundwater level in the tunnel. At the same time, grouting reinforcement can reduce the water content of rock stratum and the permeability coefficient of surrounding rock, so as to limit the water seepage of rock stratum in the tunnel, and finally realize the purpose of grouting reinforcement of loose rock mass to block the groundwater seepage channel, thus controlling water inrush. It must be pointed out that Queershan Tunnel has a natural drainage function because of its lower entrance and exit and slightly higher middle elevation.

How convenient is it to open the tunnel?

The beautiful natural scenery of Ganzi Prefecture is very attractive to go on road trip fans, but many people gave up the plan as soon as they heard that they were going to climb Queer Mountain.

Now, Queershan Tunnel has opened a new golden passage in the road trip of western Sichuan, shortening the mileage by 20 kilometers and saving the driving time by two hours. It only takes the old driver 10 minutes to cross Queer Mountain!

What are the humanized designs of the tunnel?

Queershan Tunnel has created many miracles in design and construction. From the perspective of the use of expressway, there are also rich cultural landscape settings and many humanized designs.

◆ Introduce Kangba culture and export the road-building spirit of the 18th Army.

From the entrance to the exit of Queershan Tunnel, careful passers-by will find that both the entrance and the exit have unique landscape design. The theme of the entrance is "Saint Kangba, Colorful Dege". Sculptures such as Nanpai Tibetan Medicine, Tea-Horse Ancient Road and King Gelsall stand beside the bronze tunnel, and Tibetans holding Hada are singing and dancing, welcoming tourists from all directions.

At the exit, the soldiers of the 18 Army opened the Queershan Highway. Soldiers March to build roads, using natural stone reliefs, which are integrated with the whole mountain.

◆ The hole is provided with an oxygen station to prevent high reflection.

In addition to the landscape, the tunnel has also adopted many humanized and environmentally friendly designs. During the construction period, oxygen stations will be reserved, and oxygen stations will be set at the entrance and exit of the tunnel to provide oxygen supply services for tunnel builders, managers, passing drivers, passengers and tourists.

The bend of the route is designed in the tunnel, which can not only prevent the driver from fatigue caused by going straight for a long time, but also prevent the heavy snow from being blown directly into the tunnel by the wind.

At the same time, in order to prevent groundwater from freezing, the drainage ditch is more than two meters lower than the road surface. In order not to damage the environment, the vegetation is transplanted as a whole during construction, and then moved back after construction. In the design and construction, the subgrade of the approach roads at both ends of the hole is raised as a whole to digest the excavated slag.

win an honour

In 20 18, Queershan Tunnel became the first highway tunnel project in China to be shortlisted for the "Annual Engineering Award" of the International Tunnels Association, and finally won the "Oscar Award" in the tunnel industry-brunell Trophy, which indicated that the survey, design and construction level of China highway tunnel successfully ranked among the top in the world.

Knot? language

After the completion of Queershan Tunnel, it not only avoided the third section (47,000m avalanche section) and the sixth section (2,220m debris flow section), but also reduced the section with snow thickness exceeding 1.5m in winter by about 22km. More importantly, after the Queer Mountain Tunnel is officially opened to traffic, it only takes 10 minutes for traffic to cross Queer Mountain, instead of bypassing the dangerous mountain road for more than two hours, and it is no longer closed for half a year like the old road, which can achieve year-round connectivity.

This article comes from car home, the author of the car manufacturer, and does not represent car home's position.