On May 4, good news again came from the construction site of the Yichang Three Gorges Hub Jiangnan Refined Oil Dam-Crossing Project undertaken by China Railway Seventh Group: the Sanjianxi Tunnel was successfully holed through. This tunnel is the seventh tunnel on the entire line to be holed through after the Nanchong Tunnel, efficiently completing the node target and laying a solid foundation for subsequent construction along the entire line.

The Sanjianxi Tunnel is located in Sanjianxi Village, Tucheng Township, Dianjun District, Yichang City, with a total length of 684.46 meters. It is a reverse-slope tunnel with a designed gradient of 8.56% and a maximum buried depth of 146.43 meters. The bedrock lithology is mainly thin-bedded limestone intercalated with shale; the rock is relatively soft, fractures are well developed, and the rock mass is broken. The effective overlying rock mass is relatively thin and the strata dip angle is relatively gentle, which is unfavorable to the stability of the tunnel crown, making it a key and difficult project.

Since the start of tunnel construction, the construction party has carried out overall planning, meticulous organization, and scientific arrangement, and has taken a hands-on command approach. It overcame many difficulties such as the narrow working face inside the tunnel, slow mucking, large gradient, relatively broken surrounding rock, and large water inflow at the tunnel face. Mechanical excavation was adopted, and advanced horizontal probing holes, geological radar, TSP and other detection means were used to accurately predict the surrounding rock and carry out advanced support. At the same time, multiple measures such as the "one blast, three inspections" system and toxic and harmful gas detection were taken to ensure the safe and smooth progress of the project and effectively improve the project's safety, quality, and construction management level.