On the afternoon of May 8, the North First Ring Road Station on Hefei Rail Transit Line 5, constructed by the Municipal Engineering Company of China Coal Third Construction Group, passed acceptance of its first base slab section, marking that Hefei's deepest four-level underground station has officially entered the main construction phase, setting a new record for Hefei rail transit construction. In the morning, the reporter visited the station site.

It is reported that the North First Ring Road Station is located at the intersection of Mengcheng Road and the North First Ring Road, adjacent to the Nanfei River. The station is 274.5 meters long, with a standard section width of 22 meters and a foundation pit depth of up to 34.8 meters, making it the deepest four-level station in Hefei rail transit at present.

At the construction site, several "big guys" with "tall stature and long arms" worked together with workers to complete one construction process after another in a tense and orderly manner... This morning, the outdoor temperature was 32 degrees Celsius. To seize construction progress, the site was bustling. The station's retaining structure uses domestically advanced underground diaphragm walls with sleeve-type joints, 39 meters deep and 45 tons in weight, setting the deepest and largest record for Hefei rail transit.

At the same time, glass fiber reinforced polymer rebar material for the end shaft is being used in Hefei for the first time. "This material not only has strong adhesion, but glass fiber also has high tensile strength, and its performance is basically similar to steel rebar," the team leader introduced. During the retaining structure construction, the project team set a Hefei rock-socketed underground diaphragm wall construction progress record of an average of one panel per day.

The North First Ring Road Station was originally a two-level underground station. To minimize the impact on surrounding residents, the station position was readjusted and deepened from two levels to four levels, with the deepest part of the foundation pit reaching 34.8 meters, making it the deepest station in the city's rail transit.

During the foundation pit excavation stage, equipment operating space was narrow, and the in-pit columns, concrete support beams, and steel supports crisscrossed. In particular, excavation of the rock-socketed portion of the ultra-deep foundation pit of a four-level station made conventional relay excavation and lifting extremely difficult... How were the construction difficulties solved? The reporter found the answer at the site. In addition to continuously optimizing the construction plan, the frequency of foundation pit monitoring was especially increased, an automatic monitoring system was immediately activated, and high-power breakers were deployed together with rock splitters to accelerate rock breaking. "Judging from the latest construction results, the effect is remarkable," Wen Jiyao, project manager of Line 5 Section 5B, told the reporter.

In addition, the northern section of Line 5, which the public is concerned about, has also made the latest progress. Up to now, 10 stations in the northern section of Line 5 have been capped, with 3 remaining; 14 single-track tunnels have been holed through, with 12 remaining; shield tunneling has completed 65% cumulatively; and the cumulative output value completed is 2.11 billion yuan.