At about 5 p.m. on September 20, under the gaze of all the staff on site, the cutterhead of the No. 203 shield machine equipped by China Railway slowly came out of the receiving hole gate of Jiangyang South Road Station, successfully completing the excavation task of the shield section of the second phase of Shanghai Line 18 West Changjiang Road Station - Jiangyang South Road Station, laying a solid foundation for the next step of track laying work.
Shanghai Line 18 Phase II Civil Engineering 1 Standard Changjiang West Road Station-Jiangyang South Road Station section of the downlink line is 861 meters long, a total of 692 rings, the tunnel roof is buried 7.2 meters ~ 12.5 meters, the minimum curve radius is 400 meters, and the maximum longitudinal slope is 20‰. During the shield boring period, a power tunnel pipe gallery is penetrated, and the minimum vertical net distance between the top of the section and the power tunnel pipe gallery is 5.2 meters, in the early stage of construction, the site takes corresponding measures to reduce the disturbance of the shield boring to the power tunnel pipe gallery strata, strengthens monitoring and reasonably adjusts the shield propulsion parameters according to the monitoring data; during the crossing period, strengthen the control of various shield propulsion parameters, especially shield attitude, soil silo pressure, synchronous grouting amount and synchronous grouting pressure, etc., and increase the frequency of monitoring during the crossing. Analyze the monitoring data every day and guide the shield to advance the construction in time; After the crossing is completed, the settlement deformation of the power tunnel pipe gallery is within the design allowable range, and the shield machine passes smoothly and smoothly.
The shield crossing the dense pile pulling area is a major problem faced by the shield section. There are a total of 505 piles left over from the old factory building in the direction of shield propeller. The pile pulling area disturbs the formation after pile pulling, which poses a great challenge to the control of shield attitude. During the pile pulling process, the pile hole is backfilled with cement soil in strict accordance with the construction plan, and the soil is backfilled under the tunnel to ensure that the soil under the shield is densely backfilled. For the parts where the location of the pile foundation is not clear, measures such as excavator exploration and geological radar scanning and excavation are adopted to ensure that the pile foundation is completely pulled out. At the same time, shield tools with pile grinding function were selected to cope with the risk of pile leakage.
On May 5, 2023, China Railway No. 203 shield machine was successfully launched at West Changjiang Road Station.
During the shield machine promotion period, through the control of raw materials entering the site, shield machine promotion attitude control, segment assembly control and other measures at the same time, the quality of the forming tunnel was better, and all construction indicators were within the design requirements.
In order to ensure the absolute safety of shield reception, careful planning and early deployment; Strengthen the control in the final excavation process, ensure that the measures are in place, the responsibility is to the person, strictly grasp the key operation links, and implement various safety management measures. The staff has inspected the site for many times, organized the expert review of the cave reception, put forward specific requirements for the risk points and emergency handling measures of the shield reception, and made meticulous preventive measures and guidance for the risks that may occur on the site to ensure the smooth reception of the shield.
Editor: Wen Xiting
Source: Shentong Construction