Guangzhou Metro Line 5 is 32 kilometers long, almost the sum of lines 1 and Line 2, and it is the most complicated and difficult line in the history of Guangzhou Metro construction. Tan Wen, deputy general manager of the construction headquarters of Guangzhou Metro Corporation, said that Metro Line 5 walked in the bustling urban area of Guangzhou, passing through thousands of households, crossing the fault zone seven times, crossing the Pearl River twice and crossing guangzhou-maoming railway six times, creating six national first construction miracles in difficulties. The 32-kilometer-long line runs non-stop through the "geological museum" in Guangzhou: red beds, granite strata, limestone strata, mixed strata and silty sand layers, and through fault zones, water-rich fractured strata and caves. Before the completion of Guangzhou Metro 1234 Line, many complicated geological strata were encountered, but none of them was as successful as Line 5.
For example, when Yuexiu Mountain came down, the cave was tens of meters high, and the shield machine passed through the cave, which was the first case in China. The shield machine may fall down at any time, and the machine will be destroyed; Outside the city bus station, holes, broken zones and water cover are also very dangerous, and the shield machine is advancing, which is very difficult. ...
In order to take good care of the fragile stratum, the construction party should scan the soil layer with reflected waves, do CT to see if there is any cavity, then completely fill the karst cave, and finally inject a lot of cement slurry. Before the shield passes, the worst possibility should be considered, and once the risk is found, it should be controlled. Difficult to protect, crossing 1000 building.
Because the tunnel of Line 5 runs in the downtown area of Guangzhou, it passes through a large number of houses, elevated bridges, railways and urban main roads. There are more than 1000 houses that the whole tunnel passes through, most of which are old houses, and some even are brick-wood houses in the 1960s. Any slight settlement may lead to settlement and cracking of the house.
There are more than 5 kilometers of lines parallel to the inner ring road under Huanshi Road, involving hundreds of piers of the inner ring road. The vehicles on the elevated platform are constantly flowing, and the underground dragons are shuttling. If it is not properly controlled, it is easy to cause the pier to sink and the bridge body to crack, which will endanger the driving safety. Under the railway line, the shield machine crossed the busy guangzhou-maoming railway artery six times, and the tunnel was excavated underground. More than 65,438+000 trains pass through the ground every day. If the subgrade collapses due to improper excavation control, the train will derail and roll over at any time. Risks are everywhere. However, the subway has controlled these risks and achieved advanced investigation, advanced research, advanced prediction, advanced protection and advanced planning. The construction is difficult, and the superimposed tunnel turns sharply.
The geology of Guangzhou is very complicated, and the interval between strata is often different when it is 1 m, which leads to some dangerous situations. Before the construction of the subway line, the whole line will be drilled, and a borehole will be drilled every 25 meters to detect the underground geological conditions. In order to control safety risks, subway construction personnel also adopt the "four-guide method", that is, do a lot of advanced work before the project starts: advanced exploration, advanced prediction, advanced research and advanced treatment, and formulate detailed emergency plans before the possible dangers start.
Zoo Station is the most distinctive station on Line 5. Many people don't know that there is no such station in the planning of Line 5, but citizens strongly demand to set up a station in the zoo, so the tunnel has to take a big turn. This alone will cost 65.438+0.5 billion RMB, and bring a lot of construction problems. Because the turning radius of the tunnel is small (206 meters, the conventional need is at least 350 meters), we have to adjust measures to local conditions, and the two tunnels have changed from conventional parallel to superposition. At the same time, the superposition of the two tunnels enables the line from Zoo Station to Yangji Station to turn nearly 90 degrees, avoiding the dense buildings on both sides of the road. In addition, the Zoo Station to Yangji is a single-hole tunnel with an excavation height of 18.205 m, which is the largest single-hole overlapping subway tunnel in Asia, and the construction is very difficult. The excavation height of the zoo station is nearly 22 meters, which is rare in the construction of shallow buried and underground excavation method. The structure is difficult, and it is the first long-span underground tunnel.
The most difficult thing is the district Zhuang station. Ouzhuang Station is the interchange station for Metro Line 5 and Line 6. Ouzhuang Station is located at the intersection of Huanshi East Road and Nonglinxia Road. The ground traffic at the station site is busy, so the traffic cannot be interrupted during the subway construction. There are many underground pipelines, and the station structure is very complicated. Underground excavation method is still the first in China. The main tunnel of Line 5 platform is a 24-meter wide-span underground excavation tunnel. The station of Line 6 is an underground excavation station, with three arches (the sections of three tunnels are nested), with an outsourcing width of 24. 15m, a height of 16.6m and a length of 62m. The main tunnels of Line 5 and Line 6 form a "three-layer interchange" overlapping tunnel with the No.3 passage of the North Station Hall above them. The surrounding rock of the station is red sandstone and mudstone, which is highly weathered, easy to disintegrate when it meets water, and the construction is the most difficult. It is difficult to cross the river, and the elevated tunnel crosses the Pearl River twice.
Guangzhou Metro Line 5 starts from the intersection of Fangcun District, goes eastward via Datansha Island to Zhongshan No.8 Station, and needs to cross the Pearl River twice. Among them, the section from Jiaokou Station to Tanwei Station is an overhead line, and the Pearl River tramples on Line 5. Tanwei Station to Zhongshan No.8 Station is the subway line. The subway tunnel will cross the Pearl River less than 100 meters, and the river surface will be more than 260 meters wide. Shield machines need to cross rivers with steep slopes and shallow coverage. The slope of this section is 55%. The tunnel is 600 meters long, and the ground elevation drops from 8.2 meters to 2 meters near the Pearl River Dam. The sudden change of tunnel overburden thickness poses a new challenge to the hydraulic control of the cut. A little carelessness will lead to the dam cracking or sinking and break through the Pearl River.
During the tunnel construction in 2007, the head of the shield machine was only more than 5 meters away from the turbulent river, and it was necessary to climb a big slope. Despite the difficulties, it still maintains the highest crossing speed in the country. Subway builders strictly control the excavation parameters and carefully construct. It took only 26 days to pass through the Pearl River safely, with an average of 10 meter per day, which kept the national record set by the shield machine in the construction of Metro Line 3. It's difficult to climb a mountain, and the head crosses the Pearl River.
When the subway train crosses the Pearl River in the middle direction of the bridge through the tunnel, it is almost overhead when it leaves the tunnel, which means that the train with a big slope needs to climb a big slope.
Line 5 continues to use the same L-shaped linear motor train as Line 4. This kind of train has the strongest climbing and turning ability among several subway trains. This slope is not only completely competent, but also allows passengers to sit very steadily and will not feel like riding a roller coaster. It is difficult to reduce vibration, and it is more stable to increase the cost by 500 million yuan.
In order to create a more comfortable ride environment for passengers, Line 5 draws on the successful experience of track laying construction of Line 3 and Line 4. Under the busy road section, the construction unit adopted the world-advanced British pioneer vibration reduction fasteners near sensitive road sections such as residential areas, schools and hospitals, with a total mileage of 6 kilometers. This fastener has good vibration reduction effect and wide application range, and has been applied to track lines in more than ten countries around the world. After the system is used in some lines of Guangzhou Metro Line 3 and Line 4, the vibration caused by the track can be greatly reduced, and the vibration reduction effect is very good, so passengers will feel more stable and comfortable when sitting in the car. It's just the problem of installing shock-absorbing fasteners, so the cost per kilometer increases by nearly100000 yuan. The installation is difficult, and the electromechanical installation of the station is complicated and cumbersome.
Manager Zhao Jun of the station equipment department of the construction headquarters of the subway company said that the electromechanical decoration technology of the subway station is "complex" and "miscellaneous". Although it is not as unpredictable as the civil construction stage, it is sometimes even more complicated than the civil construction stage due to limited space and other conditions, including: site handover; Construction and commissioning of central cooling station; Coordinated management of periphery and site; Comprehensive pipeline layout; Hoisting and transportation of large equipment; Construction of track area; Fire prevention and plugging of pipelines; Comprehensive debugging; Protection of finished and semi-finished products.