The Construction Plan and Its Optimization for Huzhou Tunnel of Nanjing-Hangzhou Passenger Dedicated Railway

摘要

The Huzhou Tunnel, 5510 meters long, was excavated by drilling and blasting method. The geotechnical condition of this tunnel was complicated with frequent changes of the type of surrounding rock. In addition, the shaft goes through seven faults. To speed up the construction of this tunnel, explosives were loaded in holes that were drilled in a specific pattern chosen to produce the most economical and satisfactory breakage of rock. By using the pre-arching technology for type VI and V rock, overbreak was minimized; by optimizing blast parameters for Class II and Class III rocks, smooth blasting was enhanced. As a result, the cycle of drilling -blasting - ventilating - mucking was accelerated. The parameters of rock bolting and shotcrete were optimized; the strength of in-situ lining concrete for form removal in winter and spring was improved. Moreover, an Internet-based personnel location and visual monitoring system was introduced to monitor the activities inside the whole shaft in real time under all weather conditions to ensure safety and efficiency of the construction. This paper addresses the key construction issues and difficulties related to schedule, safety, and quality that were encountered which might be common for similar projects. The Huzhou tunnel was completed within 30 months. This tunnel is fully operational at an average train speed of 350 kilometers per hour.