The commercial and business-compatible transportation facility project at Hangzhou Zhengchu [2015] No. 51 plot, undertaken by Hangzhou Construction Engineering under the City Investment System, is located at FG01-C2/U2-01 plot, Hubin Unit, Shangcheng District, Hangzhou. Specifically, it is situated in Shangcheng District, Hangzhou, adjacent to Banqiao Road to the east, Yan'an Road (Metro Line 1 and Longxiangqiao Station exit) to the west, Xueshi Road to the north, and Gonglian Building and Pinghai Wangjiao to the south.
The shield tunnel immediately west of the project is Hangzhou Metro Line 1 (Longxiangqiao Station and Longxiangqiao–Fengqi Road section), which is already in operation. The basement boundary of the foundation pit is approximately 9 m from Line 1 station at the closest point, about 0.57 times the excavation depth (excavation depth is 15.95 m); the tunnel crown depth is 7.284 m (shallower near Longxiangqiao Station); the closest distance from the excavation boundary to the Line 1 running tunnel is 15 m (about 0.88 times the excavation depth). The construction is difficult and risky.
To ensure the safety of the operating Metro Line 1 shield tunnel and Longxiangqiao Station, and to avoid risks during construction, the project department, before construction within the adjacent metro protection zone (50-meter warning line), together with the owner, metro group, and supervision company, conducted inspections, measurements, and records (main conditions, cracks, leakage, positioning, etc.) of the Metro Line 1 and Longxiangqiao Station area within the influence range of the foundation pit.
The project department proactively contacted and maintained coordination and communication with the metro monitoring department. Together with the metro monitoring department, they reviewed the survey results table, positioning points, general layout plan, measurement control network, control points, and other drawings provided by the construction unit, and set out the outer contour of the foundation pit, to ascertain the specific location and alignment of the metro tunnel and the minimum distance between the metro tunnel and the foundation pit, ensuring that the relative distances to the metro station and tunnel meet requirements.
At the same time, an expert advisory group was established with experienced experts to leverage their technical expertise to reduce the impact of construction on metro facilities. Technical briefings were strengthened, with emphasis on the impact of each construction process on the metro, precautions, and emergency plans, ensuring that each process is constructed strictly in accordance with design and specifications, and no unauthorized or cross-boundary construction is allowed. Machinery and materials of good performance and sufficient quantity were strictly provided to ensure normal construction.
During the construction of each process on the metro side, the project department will first conduct trials and timely monitoring, and based on the trial results, decide whether to apply the construction method on a large scale. If necessary, they will jointly study and adjust construction measures with relevant parties.
On the side near the metro, no storage yard, rebar cage fabrication yard, mud pit, sewer, or sump is set up on the construction site. To protect the metro and reduce road load, the project department also assigned personnel to direct traffic, strictly prohibiting heavy engineering vehicles from passing over the shield tunnel line on Yan'an Road outside the site.
Through this comprehensive control before, during, and after construction, both on and off site, it is believed that the project department will successfully overcome the difficulties of deep foundation pit construction adjacent to the metro and establish a quality project built by Hangzhou Construction Engineering Group in the city center of Hangzhou.