On February 28, the first shield tunnel section of the Shenyang Underground Utility Tunnel (South Canal Section) Project achieved breakthrough one month ahead of the original plan, marking that the Shenyang Underground Utility Tunnel (South Canal Section) Project has met the conditions for pipeline installation, which plays a decisive role in the official operation of the tunnel by the end of the year.
The Shenyang Underground Utility Tunnel (South Canal Section) is one of the first ten pilot cities for national urban underground utility tunnel construction, listed by the Ministry of Finance as a national PPP demonstration project, and is also the first PPP project in Shenyang to enter the execution phase. The project starts from the green belt on the north side of Wenti West Road along the South Canal in Shenyang and ends at the south side of Hemu Park. The main tunnel is about 12.63 kilometers long and includes a “heating compartment”, “natural gas compartment”, “water and communication compartment”, “power compartment”, and “emergency escape passage”, covering six major types of utility pipelines: power, communication, water supply, reclaimed water, heating, and natural gas.
It is reported that the section achieving breakthrough is the shield tunnel section on the south line from Qingnian Park to Wanliutang Park, with a length of 2,253.837 meters. The shield machine was launched on July 17, 2017, and received on February 28, 2018, with a total construction period of 227 days. More than one-third of this shield section is located directly beneath the South Canal riverbed. The stratum types are complex and variable, and many sections contain cobbles larger than 30 centimeters, which increased the difficulty of shield tunneling. At the same time, the “V”-shaped slope tunneling method was used to pass under multiple overpass obstacles. When passing under the North-South Expressway tunnel, the clear distance between the top of the utility tunnel and the bottom of the tunnel was only 3 meters. During construction, we successively overcame multiple technical challenges and successfully avoided safety risks, achieving breakthrough one month ahead of the original plan, and striving to meet the conditions for pipeline installation in April.”
It is understood that the Shenyang Underground Utility Tunnel (South Canal Section) is the first underground utility tunnel project in China constructed using the shield method. The utility tunnel adopts a double-line single-circle structure, with a single-circle shield excavation diameter of 6.25 meters and an inner diameter of 5.4 meters. Currently, a total of 12 shield machines are operating underground across the entire line, each advancing about 12.12 meters per day. The entire line is expected to achieve breakthrough by the end of September, and project construction is expected to be completed and trial operation of the utility tunnel to begin by the end of the year.
According to a responsible person from the Shenyang Municipal Construction Commission, once the Shenyang Underground Utility Tunnel (South Canal Section) Project is completed, it will integrate municipal supporting pipelines into one system for unified planning, design, construction, and management. It will effectively solve problems such as repeated road excavation, dense overhead line networks, and frequent pipeline accidents in urban areas, and will effectively safeguard urban safety, improve urban functions, beautify urban landscapes, and promote intensive, efficient, and transformational urban development. At the same time, as China's first underground utility tunnel built by shield tunneling through an old urban area, its innovative construction techniques and methods will provide reference experience for the nationwide promotion of innovative construction techniques and methods for underground utility tunnels in old urban areas in the future.