Recently, as the "DZ055" shield tunneling machine broke through the soil, the left line of the shield tunneling section from Jida Fourth Hospital to Feiyue Road in the Second Work Area of the Phase I Project of Changchun Rail Transit Line 7, in which the Sixth Company of China Railway Construction Bridge Engineering Bureau Group participated in construction, achieved breakthrough. At this point, all 6 shield tunneling sections under the company's responsibility have achieved breakthrough. The construction task was completed one month ahead of the milestone schedule, making it the first work area on the entire line to achieve full tunnel breakthrough of underground works.

According to reports, the construction task of the Second Work Area of the Phase I Project of Changchun Rail Transit Line 7 consists of 4 stations and 6 sections. The 4 stations are Qiche Park Station, Xisihuan Station, Xing'an Road Station and Anqing Road Station. The 6 sections are the Kaoshantun depot access line section, the Qi-Xi section, the Xi-Xing section, the Xing-An section, the An-Fei section and the Fei-Ji section, totaling 13,160 meters of double-line shield tunneling section, 110 meters of open-cut section and 220 meters of mined section.

During the construction of the shield tunneling sections, a total of 5 shield tunneling machines were deployed. During the construction of the 12 single-line sections, a single shield machine was relocated 3 times, and lifting operations for launching and receiving shafts totaled 24 machine-times. To ensure the safe and smooth breakthrough of the shield tunneling sections during construction, the project's shield management team formulated a "four-step" plan. Before shield tunneling, special construction plans were prepared, and experts were invited multiple times for review to ensure the scientific validity and feasibility of the plans; reserve work was done for materials such as segment linings, consumables, synchronous grouting mortar, cement and sodium silicate to ensure no delay in progress. During shield tunneling, close attention was paid to all parameters of the shield machine and timely adjustments were made, earth chamber pressure was strictly controlled, and the muck discharge volume and synchronous grouting quality were constantly monitored to ensure smooth shield tunneling. Difficulties such as undercrossing heating pipelines, petroleum pipelines, the ring expressway and high-pressure natural gas pipelines, and side-crossing elevated bridge piles were overcome successively. After the shield breakthrough, secondary grouting behind the tunnel wall was carried out in a timely manner, providing a second guarantee for the safety of the tunnel and the ground.