How does “Jinghua” shield machine cut through the mountain with low carbon
Have you ever wondered how a 7.3 km long underground tunnel was born?In the traditional image, tunnelling involves thousands of workers digging through mountains, drilling holes and firing cannons, as rocks slide and dust rises from the construction site.Today, however, the reality is quite different.Recently, the reporter followed the 2022 “Spring Tour to grassroots” media team organized by China Journalists Association and China Association of Industry Newspapers to the Beijing East sixth Ring Road reconstruction project site of China Railway 14th Engineering Bureau.Here, the Jinghua shield machine is about to dig 59 meters into the ground, and 2,400 meters of tunnel has taken shape.The east sixth Ring Road reconstruction project is of great significance to the improvement of Beijing’s transportation service level, the promotion of beijing-Tianjin-Hebei regional transportation integration and the construction of a comprehensive transportation system.Among them, the beijing-Tianjin Highway to Luyuan Second Street section is the tunnel section, the length of the shield section is 7336 meters, the diameter of the shield tunnel is 15.4 meters, the largest diameter of the shield tunnel in north China.Shield machine is a kind of tunnel boring machine using shield tunneling method, mainly used in railway, highway, subway and other infrastructure projects.Down the shaft elevator, came to the underground platform 30 meters, in the front end of the tunnel, the reporter saw the diameter of 16.07 meters, 150 meters long, weight 4300 tons of “Jinghua” shield machine, see the east sixth ring transformation of the west line of the shield tunnel main force of the real face.”Jinghua” consists of five groups of connected wagons, each with different functions.”When ‘Jinghua’ shield tunneling machine, excavation, drainage, slag, support, lining, sealing and other links can be completed at one go, the main structure of the tunnel can be formed at one time.”China Railway 14th Bureau Beijing East sixth ring renovation project department project director Sun Xutao told reporters.On September 27, 2020, “Jinghua” rolled off the line in Changsha, becoming the third largest excavation diameter shield machine in the world, marking that China’s super-large diameter shield construction technology ranks among the top in the world.However, in the construction process of shield tunneling in the west line of Beijing East sixth Ring Road reconstruction project, “Jinghua” shield tunneling machine needs to pass through complex geology such as sandy soil, water-rich and high-density sand layer, silt and clay interlayer.For solving technical problems and “jinghua” driven by the fourth generation atmospheric change knife, telescopic master, large diameter overloading segment efficient transship and assembly technology, efficient high-power muddy water circulation system, high precision excavation face gas-liquid balance control of a number of core technologies such as independence, overcome engineering faced with large diameter, long distance, deep soil, super sensitive environment, such as construction difficulties,Effectively ensure the construction process.Chen Peng, the first generation of “shield captain” of China Railway 14th Bureau, told reporters that on May 18, 2021, the “Jinghua” shield machine was officially launched. In 2021, the “Jinghua” shield machine tunnelling broke through the 2000 meter mark. At present, the shield machine has tunnelling to 1200 rings and formed a tunnel of 2400 meters.The circulation system ensures that the site is clean and the shield machine continues to dig forward, but the construction site is clean and spotless. The original dusty scene did not appear. Why is this?According to Sun, “Jinghua” is divided into push, grouting, assembly, mud circulation, sealing and other five parts of the system.When the shield machine drives, the front cutter plate “eats” the soil, and the mud water in the pipeline is first input to the shield machine cutter head, and the muck that is cut down is washed after pressure.The mud of mixed muck is transported to the mud treatment plant on the south side of the excavation site by the drainage pipeline for treatment.The mud is filtered and settled and recycled to the shield machine.On the inner wall of the tunnel, the reporter saw two white pipes, above which were marked “slurry pipe” “slurry pipe” words.Sun told reporters that these pipes are the “blood” for the jinghua shield machine to carry out mud circulation.”When the slurry comes into the treatment plant, it is pre-screened, dehydrated and then pumped into a flow feeder for centrifugal separation, like the drum of a washing machine, where heavier particles are thrown out and dropped off to further filter.”Mud treatment plant director Hu Xiuzhi told reporters about the processing process of the mud treatment plant, “finally mud through the sedimentation tank for four precipitation, containing particles less than 0.02 mm is the standard, can be returned to continue to transport muck.”The treated muck becomes almost dry, and is eventually transported to the designated muck plant. After further treatment, it can be used for planting land, planting trees, roadbed construction, etc., to achieve resource recycling.The giant Jinghua is not only huge, but also uses a staggering amount of power.There are thousands of electric equipment such as gantry crane, mud water circulation system and steel bar processing on the reconstruction project site of Beijing East sixth Ring Road, and the installed power of the whole project reaches 37700kW.In the previous month, the project’s electricity bill totaled 4 million to 5 million yuan.”The saving of every device is the basis of solving the problem of running and leaking and realizing the goal of ‘double carbon’.Only when the foundation is solid can we achieve the purpose of saving and reducing unnecessary energy consumption.””Said Zhang Jian, director of the east sixth Ring Reconstruction project.Based on this goal, Beijing east six ring project actively explore shield construction, low carbonization of shield construction in the country for the first time application installed intelligent monitoring and control device of energy consumption of all switching station, level 1 box of energy consumption monitoring, at any time use of energy, and intelligent analysis on the remote device, reduce unnecessary energy consumption.Sun Xutao told reporters that the system through all 10kV switch stations, transformers, distribution box real-time energy consumption data remote acquisition, complete calculation and analysis, guide the construction site to adjust equipment, so as to improve the transformer operation efficiency.At the same time, the system can master the energy use of the main equipment at any time, shut down unnecessary electrical equipment or reasonable off-peak use, reduce unnecessary energy consumption and paid electricity bills.Zhang jian told reporters that the project has installed nearly 100 equipment at the construction site, which is estimated to save about 400,000 yuan of electricity, equivalent to reducing carbon emissions of more than 500 tons, and it is expected to install another 200 such equipment in the future.