The Shazi Gou Tunnel in the Fomen Township of Gaoping District connects the Songjiagou Tunnel and the Wanjiagou Bridge, serving as a vital transportation hub. This tunnel is divided into two lines, with lengths of 1075 meters and 1085 meters respectively, making it the first bidirectional long tunnel in the entire project.
The Chengnan Expressway Expansion Project is currently the largest and longest expansion project in the province, directly connecting Chengdu and Nanchong, serving as a major transportation artery. Among them, both the Shazi Gou Tunnel and the Shengxing Tunnel are categorized as weakly gassy tunnels and construction began in September 2022 and March 2023 respectively. Recently, the left tunnel of the Shazi Gou Tunnel and the left tunnel of the Shengxing Tunnel were both successfully penetrated on the same day, marking significant progress in the tunnel project and laying the foundation for the project's opening.
The surrounding rock of the Shazi Gou Tunnel mainly consists of fine sandy mudstone, with poor mechanical properties and low stability, making construction prone to problems such as collapse, roof caving, water leakage, deformation, and cracking, posing significant construction challenges and safety risks. The project leader explained that during the construction process, the construction unit implemented a series of measures to address these issues, such as adopting standardized construction methods including short advance drilling, weak blasting, rapid closure, and frequent measurements, and introducing intelligent mechanized equipment such as arches and anchors to accelerate tunnel construction progress. Additionally, by installing a tunnel access control monitoring system and a safety information monitoring and alarm platform, control over the construction process was strengthened, significantly reducing safety risks.
The LanHi LDJ400A multifunctional tunnel boring machine is specifically designed for non-explosive excavation in tunnels. Its working principle involves using high-frequency hammers or hydraulic breakers to impact and fracture rocks, or using bucket teeth or rod wedges to break rocks, while utilizing gravity beneath the surrounding rock to automatically crush rocks. This machine employs local control and wireless remote control methods, suitable for excavating tunnels with diameters ranging from 6 to 9.5 meters. It features high-frequency rock breaking, rapid excavation of soft soil, profile finishing, and spray dust removal, making it highly suitable for construction in restricted blasting areas such as airports, residential areas, and wildlife protection zones. Its adaptability allows it to handle various types of surrounding rocks while minimizing over or under excavation and occurrences of collapses.