The Huzhou–Hangzhou West–Hangzhou–Huangshan High-Speed Railway Connecting Line Project, Contract Section HHLJXZQ-2, comprises seven tunnels with a total length of 10.825 km. The main tunnels have excavation cross-sectional areas ranging from 128.55 m² to 152.4 m², making them large-section tunnels.
Our company was responsible for the tunnel blasting operations and mobilized to the project site in April 2020. Starting with just two teams, we rapidly expanded to 11 teams and mobilized more than 100 personnel involved in blasting operations within just two months. Since April 2021, the tunnels have been completed one after another. All seven tunnels have now been fully excavated and connected. During normal construction, the average monthly advance exceeded 130 meters, with the fastest monthly advance reaching approximately 160 meters.
At the tunnel portals and along the western side of the tunnel sections, existing Ningbo–Hangzhou High-Speed Railway facilities were located within 100 meters of the blasting areas, with the nearest surrounding buildings approximately 38 meters away. These conditions placed particularly stringent requirements on the control of flyrock and blast-induced vibration, significantly increasing the difficulty of the blasting operations.The project teams addressed the vibration-control challenges by optimizing blasting parameters and carefully controlling the delay intervals between initiation stages. Each waveform was analyzed in detail, and comprehensive measures were developed covering inter-hole delay times, hole spacing and arrangement, drilling positions, explosive charge per hole, and initiation sequence. Within the same blasting section, the delay times between individual holes were repeatedly tested and adjusted. The initiation sequence was also alternated between the side closer to and the side farther from the existing railway. Blasting parameters were further adjusted according to variations in rock structure and hardness. Through this meticulous optimization, the project achieved an effective balance between blast vibration control and excavation advance.
The successful completion of the Huzhou–Hangzhou High-Speed Railway tunnel project demonstrated the company employees’ strong sense of responsibility, teamwork, and commitment to service. It also showcased the company’s technical expertise in tunnel blasting, opening a new chapter in its tunnel construction operations and earning widespread recognition from all parties involved.
