On January 25, the reporter learned from the Third Company of CCCC Third Harbor Engineering Co., Ltd. that recently, with the completion of pouring 17 cubic meters of concrete for the last bored pile——the open-cut section base slab pile, all 6,110 bored piles in the Mashan section of the Taihu Tunnel project have been completed. This also marks that the Mashan section of the Taihu Tunnel has fully entered the main structure construction phase.

The Changzhou-Wuxi section of the Suzhou-Wuxi-Changzhou South Expressway is part of the "Fifteen Radiating, Six Vertical and Ten Horizontal" expressway network plan of Jiangsu Province, among which the Taihu Tunnel is a key control project of the entire line, with a total length of 10.79 kilometers and a net width of 17.45 meters. It is currently the longest under-construction sub-lake tunnel in China.

The reporter learned that after the Mashan section project department undertaken by CCCC Third Harbor Engineering Co., Ltd. entered the site, facing unfavorable factors such as complex geological conditions and difficult pipeline relocation, the project department carefully organized and scientifically carried out construction, and successfully poured the first bored pile on May 4, 2018. The 232 bored piles in the open-cut section of the tunnel were the toughest "hard bones" to crack. Because the open-cut section crosses Liuli River, 62 base slab piles are located in the river channel. The project department temporarily blocked the Liuli River within the red line, pumped out the river water, arranged excavators to clear the river channel, and then carried out layered backfilling and compaction of earthwork again. For pile foundation construction, 4-meter-long casings were embedded to pass through the backfilled soil area, avoiding hole collapse during bored pile construction in the river backfill area and preventing impact on pile quality.

In addition, there was another thorny issue in the pile foundation construction of the open-cut section——underground pipelines. Because the original pipelines along the line crossed the Taihu Tunnel route, the project department checked the local pipeline layout drawings and found that a 10 kV high-voltage cable was buried under the base slab pile construction area at a depth of 7 meters. The unclear direction and location of the pipeline brought great inconvenience to construction. To ensure construction safety, the project builders prepared a cable excavation protection plan, communicated and discussed with the local power department many times, and under the supervision of personnel from the pipeline unit, the project department adopted manual excavation and exploratory excavation to determine the actual location and direction of the cable, finally successfully completing the construction task of 232 bored piles in the open-cut section.

It is reported that the Taihu Tunnel project will be fully completed by the end of this year. It is expected that after the project is completed, it will effectively enhance the functional role of the Shanghai-Nanjing corridor as a major national comprehensive transportation channel, be of great significance to the development of Suzhou, Wuxi and Changzhou cities, and become a new engine driving the economic development of the Yangtze River Delta.