Subway repair artifact: Jinan made shield machine
on December 18, at about 11 meters underground of the extension line of liuchangshan road in Jinan, the shield machine that has been driving for five months will soon come out of the well to open up the first tunnel section of Jinan rail transit line R1. The total length of this section is 1302 meters. Now 1210 meters have been completed, and there are about 90 meters left to run through
following line R1, the first shield machine of line R3 will be offline at the end of January next year, and line R2 is also expected to usher in the first shield machine in September next year. As a special engineering machine for tunneling, the starting time of shield machine is the most critical time node for underground construction of rail transit, which is directly related to the construction progress of rail transit. So how does the shield machine work underground
[successful "crossing"] the shield machine undercrossed the Beijing Shanghai railway with almost zero ground settlement
at 7:00 a.m. on November 23, with the completion of the assembly of the last ring tunnel segment, the construction of Jinan metro line R1 Undercrossing the existing railway for the first time in 13 days was successfully completed. The shield machine manufactured by Jinan Heavy Industry Co., Ltd. crosses a total of 8 railway lines, carrying nearly 100 passenger and freight trains per day. It is a class I railway with busy operation. The buried depth of the tunnel in the right line under the railway subgrade section of the section is 16.8m; The Undercrossing point of the left line is located at the junction of railway bridge and culvert and subgrade. The tunnel top of the railway frame bridge and culvert section is 7.6 meters away from the bottom of the bridge and culvert. The construction is difficult, the safety risk is high, and there are many uncontrollable factors. In the 65m length of shield tunneling under the railway, the geology changes from silty clay to pebble layer. Due to the large water content in the pebble layer, long-term shutdown will cause large stratum settlement, so the continuity of tunneling construction must be ensured
it was found at 69 monitoring points of railway subgrade, bridge and culvert that the maximum settlement at the place where the shield machine is running is not more than 1mm, which fully meets the design control standard of maximum settlement of 6mm. The success of this underpass proves that the adaptability of shield machine construction in Jinan stratum is good, which can meet the high control index requirements of the guide line that the tunnel underpass the existing line and cannot directly plug and unplug the load sensor
[made in Jinan] according to the geology, the shield machine was "customized" with a cost of more than 50 million yuan
the shield machine successfully "crossed" the Beijing Shanghai railway, and Jinan Heavy Industry Co., Ltd. has long been full of confidence in it. "Jinan is high in the South and low in the north, close to the remaining vein of Mount Tai in the South and the alluvial plain of the Yellow River in the north. Soft soil, sandy pebbles and limestone are alternately distributed in the stratum, and karst fissures are strongly developed, forming complex and unique geological and hydrological conditions." Xujingwei, technical director of shield machine of Jinan Heavy Industry Co., Ltd., introduced that the shield machine they produced was a composite shield machine tailored for Jinan. The cutter head is equipped with 41 edge high-strength material hobs, as well as tearing knives and scrapers. The sand is cut into small pieces by the hob and the tearing knife, and the scraper scrapes off the gravel and soil. The three kinds of blades have different height differences and work together. The cutter head of the first shield machine weighs 65 tons, and it took eight welders 40 days to weld it, with a total cost of more than 50 million yuan
some people ask why the R1 line does not use the traditional drilling and blasting method because the shield machine is so "expensive"? It is understood that the drilling and blasting method cannot be used in the underground section of line R1. Xu Jingwei said that the groundwater in the west of Jinan is rich, and the groundwater yield cannot be controlled by drilling and blasting. In addition, R1 line will go under the Beijing Shanghai high-speed railway and Jinan west railway station. There are uncontrollable factors in the drilling and blasting method, which will affect the passage of the high-speed railway in case of improper operation. In addition, when the shield machine is working, the movement and static are very small. During the construction process, there is no large-scale demolition on the ground, no traffic interruption, no noise during construction, and the ground basically does not subside, which does not affect the normal life of residents. Compared with the two, shield machine is obviously more safe and controllable
[earth digging "artifact"] 41 hobs open the way, dig in front and assemble tunnel segments behind.
Wang Bozhi, chairman of Jinan Heavy Industry Co., Ltd., said, "although the shield machine is large, with a total length of 85 meters and a total weight of 515 tons, it is very 'smart'. The main control room is the" brain "of the shield machine, with four touch screens inside, which display various data and real-time monitoring images of the host machine, and there are rows of buttons on the console. After the shield machine is working, the driver should keep his eyes on the screen, pay attention to the constantly changing data on the screen, touch the screen from time to time, and call up the screen required by the stress in the formula (3). Unlike driving a shield machine, we should always pay attention to the changes of various data, such as ensuring the balance between the pressure in the bunker and the external pressure, and ensuring that the axis error of excavation will not exceed 2mm per kilometer. Although there is usually only one person in the main control room, it is necessary to control and monitor the direction and speed of the shield machine, maintain pressure balance, and control all necessary procedures in the process of propulsion, such as spraying foam agent, rotating the cutter head, grouting...
"the shield machine excavates a tunnel 10 to 20 meters underground on average." Xu Jingwei said that Dun did a good job in packaging waste treatment and resource recycling. After the construction started, driven by hydraulic pressure, it only moved forward and did not retreat. The whole shield machine will look like a small train when it runs. After the excavation in front, the machines and equipment behind will assemble the tunnel segments and transport the excavated muck to the excavated "foundation pit" in time. It is lifted to the road surface by crane and then transported away by engineering vehicles. When encountering rocks, the shield machine can rotate 3.5 revolutions per minute and advance 7mm; When encountering soft soil, it can turn 1 turn per minute, and the international influence of the plastic extruder industry continues to rise by 0 mm to 80 mm