On November 20, after intensive assembly, blind pushing and translation, and commissioning, the shield machine for the left line of the Wenhuaguangchang Station–Gongnong Dalu Station section of the Liugongqu project of Changchun Metro Line 5, undertaken by Chengtong Company of China Railway No. 2 Engineering Group, was successfully launched. This is the first shield machine successfully launched for the project, marking that the project has officially entered the shield construction stage.

The left line of the Wenhuaguangchang Station–Gongnong Dalu Station section has a total length of 1,254 meters, a minimum curve radius of 350 m, and a maximum design longitudinal slope of 24‰. The geology of the section is composite strata dominated by clay, silty clay, and weathered mudstone, with a relatively high groundwater level. The shield machine is launched from within the mined tunnel at the small-mileage end of Wenhuaguangchang Station and must successively overcome multiple construction risk sources, including crossing the entrance/exit structure of Line 2, the pump house of the Water Affairs Group, Xiaonan Lake, the Hongqi Street commercial building complex, and the Hongqi Street civil air defense shopping mall. It will then be received in the cross passage at the large-mileage end of Gongnong Dalu Station, where it will be dismantled, translated, and lifted out. The surrounding environment for shield tunneling in this section is complex, and construction is difficult.

To ensure the smooth launch of the shield machine, the project department precisely controlled the preparation conditions for shield launching, clarified the division of labor, and assigned responsibilities to individuals. It held multiple special meetings before shield launching, carefully organized personnel safety education and technical training, fully carried out advanced geological forecasting and monitoring measurement work, investigated and analyzed various risk sources as well as the surrounding environment and geological conditions in advance, and formulated targeted and robust technical measures to minimize the safety risks of shield tunneling to the greatest extent. At the same time, on the basis of existing mature construction methods, it continuously innovated and optimized them, and considering construction safety, quality, and efficiency, formulated the construction method most suitable for this project to form a construction plan that is more instructive and implementable on site. Through the unremitting efforts of all employees, the project construction team safely and efficiently completed various key processes, including lifting the shield machine into the shaft and assembling it, in-station translation, shield posture positioning and reaction frame installation in the small space of the mined tunnel, equipment commissioning, and acceptance of launch conditions, successfully fulfilling the shield launching milestone target.

It is understood that the winter construction period for the left line of the Wenhuaguangchang Station–Gongnong Dalu Station section lasts as long as five months, with the outdoor minimum temperature reaching minus 28 degrees Celsius. To reduce the impact of the low-temperature environment on construction production, the project adopted a series of insulation measures tailored to local conditions: setting up a segment waterproofing construction and fuel insulation shed on the ground to ensure the bonding quality of waterproof materials; using heating tape wrapping for pipeline insulation to ensure the normal operation of pipelines and the water supply system of the shield machine; and using insulated warehouses together with heating equipment to ensure the normal storage of various shield construction materials, laying a solid foundation for subsequent smooth shield tunneling.