Across the Xiangjiang River!Xiangya Road river crossing channel smoothly through the north line

2022-04-24 0 By

Changsha Evening News On January 26, changsha (all media reporter Chen Huanming correspondent Zhou Yiqun Liu Fuchang intern Liang Jue) At 9:58 on January 26, at the intersection of Xiangya Road and Xiangjiang Middle Road in Kaifu District, after more than 300 days and nights of fighting, the “Xing Sheng” shield machine huge knife disc broke the wall and came out.Xiangya Road river crossing channel north line tunnel smoothly completed.This is the largest diameter shield tunnel under construction in Hunan province and the first two-way six-lane tunnel across the river in Changsha.After the north line shield tunnel is completed, “Xingsheng” shield machine will carry out disassembly, transfer and secondary assembly and debugging, and continue to “fight” the south line shield tunnel tunneling.The Xiangya Road crossing channel is expected to be completed and open to traffic in 2023, which will greatly improve the river crossing capacity of changsha central city, and is of great significance to facilitate the residents’ travel and strengthen the coordinated development between the regions of Changsha city.Xiangya Road crossing project is located between Sany Avenue and Yingpan Road, from Yuelu Road in the west to Furong Road in kaifu District in the east. The total length of the tunnel is 4180 meters, of which 1429 meters are constructed by shield tunneling across the Xiangjiang River. The tunnel is designed to be two-way with six lanes.The project is invested and constructed by Changsha City Development Group and constructed by China Railway 14th Engineering Group.26, at the western end of Xiangya Road, separated by xiangjiang River, a shield machine equivalent to a 5-storey building has revealed its “head”.”The ‘Xingsheng’ mud-water balance shield machine we used is tailormade for the Xiangya Road crossing channel. It has a diameter of 15.01 meters, a length of 130 meters and a weight of 4,100 tons. It is the largest shield machine crossing the Xiangjiang River so far.”Changsha City development Group project manager He Jun told reporters that the shield machine since March 30 last year, has passed through the yuxiang mill historical buildings, xiangjiang river levee, jiangzhong fault zone, operation of the subway and other high risk sources, overcome the onset of large slope small curve, long distance high strength rock excavation and other construction problems.Especially when crossing the middle section of the river, the shield traverses the breezy SLATE stratum in a long distance, with dense fault zones and uneven hardness, which easily leads to abnormal tool wear.The tool is equivalent to the “tooth” of the shield machine, which plays the role of swallowing stone and chewing soil.”After repeated research and demonstration, we use a high wear resistance, long life and heavy duty cutter, compared with the traditional steel hob, its wear resistance is higher, longer service life, to achieve the composite hard rock formation 500 meters without changing the cutter, greatly improving the tunneling efficiency and construction safety factor.”China Railway 14 bureau group shield manager Zhou Zan said.Even so, it is inevitable to change the cutting tool in the process of shield tunneling.Zhou Zan introduction, “star”, during the project has 6 round organization professional divers in knife, into the storehouse is due to the pressure brought into the storehouse, construction personnel can only work within 1 ~ 3 hours, then substitution to replace back into the storehouse, accumulated into a storehouse of more than 500 times, replace the tool with more than 300, created the largest diameter of dribbling pressure change knife records;The rock excavation reaches 180 meters per month and 270 meters per month, which has accumulated valuable experience for shield construction of the same type of river bottom.After crossing two fault fracture zones, “Xingsheng” tunnelled eastward from the southern shield in June. The biggest “obstacle” was the two fault fracture zones at the bottom of the river.The total length of these two broken zones is 245 meters, of which 75 meters is the overlap zone between broken zone and shallow overburden soil, and the minimum overburden soil is only 7.8 meters, less than 0.6 times the diameter of the hole. The overburden soil is pebble layer, with strong permeability and weak formation pressure holding ability.At the same time, the tunnel has a 5% uphill slope, a plane turning curve radius of 975 meters, and less than 50 meters from the east bank of the Xiangjiang River levee, so the construction control is difficult, high risk, is the biggest risk source of the whole line.After expert consultation and argumentation, the project adopts pretreatment measures such as grouting reinforcement in the river;Before entering the crushing zone, special maintenance inspection and knife changing operation of the shield machine and its auxiliary equipment were carried out.During the crossing process, the parameter management should be strengthened to minimize the disturbance to the formation.”We urge the key positions of the construction units to conscientiously perform their duties, fine management, 24 hours of uninterrupted monitoring and inspection, and in the tunnel and the river prepared sufficient emergency supplies, equipped with telescopes and boats to carry out round-the-clock patrols on the river.”He Jun said that through a series of measures, “Xing Sheng” shield machine in the broken zone of the smooth progress, there was no roof, slurry, collapse and other accidents in the river, and finally successfully overcome this “obstacle”.In addition, the river crossing of Xiangya Road was implemented at the same time as metro Line 6, and the open-cut section overlapped with the shield section of metro partly, resulting in large mutual interference and many control nodes.The project overcame the difficulties of complex surrounding environment, intensive construction (structure) along the line, close distance, shield machine receiving well only 80 meters away from the Xiangjiang River, rich groundwater resources and so on, successfully completed the north line of the tunnel through, laying a good foundation for the subsequent construction.After the north line shield tunnel is completed, the shield machine will be disassembled and transferred to hexi initial well for secondary assembly and debugging, and the south line shield tunnel driving will begin. It is expected to realize the south line shield tunnel starting in June this year.