Speed of 350 kilometers per hour! The First Tunnel of China's Urban High Speed Rail is under Construction | Tunnel | Speed
At 7:58 am on June 21st, at the construction site by Yangcheng Lake in Weiting Street, Suzhou Industrial Park, Jiangsu Province, with excavators breaking through the soil layer, it marked the excavation of the foundation pit for the entrance of the Suzhou East Tunnel of the Nantong Ningbo high-speed railway, which is the largest high-speed railway tunnel in the country. This is also the first foundation pit excavated on the entire Nantong Ningbo high-speed railway line.
The shield tunnel section of Suzhou East Tunnel has a total length of 11.82 kilometers and is currently the highest construction standard and longest high-speed rail urban tunnel with a speed of 350 kilometers per hour in China. It is known as the "first tunnel of China's urban high-speed rail". The tunnel adopts a super large diameter 14.8 meter shield tunneling, with a T-shaped starting section and a total length of 600 meters, including the starting shaft of the shield machine and the open cut section at the entrance. The starting well is 23 meters long, 22.7 meters wide, and 20.05 meters deep; The imported open cut section is 577 meters long, with a maximum excavation width of 31 meters and a maximum excavation depth of 16.69 meters. The total excavation volume of the shield tunnel starting section foundation pit is about 60000 cubic meters. It is reported that Suzhou has a well-developed water system and is known as the "Venice of the East". The underground water system along Yangcheng Lake is well-developed and densely distributed, and specific geological conditions result in rich water content in the confined aquifer of the shield tunnel starting section of Suzhou East Tunnel. The water pressure is high, the excavation depth of the foundation pit is large, the space is small, the excavator rotation is difficult, and the construction characteristics are complex geological conditions, difficult settlement control, and high safety risks.
To ensure the safety of foundation pit excavation, the project construction management unit Shanghai Hangzhou Passenger Dedicated Company, together with the construction unit China Railway 14th Bureau Project Department, carefully surveyed the geological conditions, scientifically formulated construction plans, safety measures, and precipitation countermeasures, conducted technical and safety briefings in advance, and carried out emergency drills such as foundation pit leakage and surge. In construction operations, follow the principle of "trench support, support first and then excavation, layered excavation, and strict prohibition of over excavation", quickly excavate and support, and reduce the exposure time without support. At the same time, a layered and segmented construction method is adopted, with a total of four layers of operation. The support adopts the form of "concrete support+steel support". During construction, the monitoring data of precipitation settlement is closely monitored, and the development trend of settlement or inclination is closely monitored to ensure the safety and stability of foundation pit excavation. After the excavation of the foundation pit at the starting section of the shield tunneling is expected to be completed in late July this year, it will be transferred to the construction of the main structure layer and side walls.
The Nantong Ningbo high-speed railway line starts from Yancheng to Nantong West Station, passes south through Suzhou City, Jiangsu Province, Jiaxing City, and Ningbo City in Zhejiang Province, and introduces Ningbo Hub Ningbo Station. The new line is 301 kilometers long, with a design speed of 350 kilometers per hour and a construction period of 5 years. There are 10 stations along the entire line, including Nantong West, Zhangjiagang, Changshu West, Suzhou North, Suzhou South, Jiashan North, Jiaxing South, Haiyan, Cixi, and Zhuangqiao. Among them, Changshu West, Suzhou South, Jiashan North, Haiyan, and Cixi are newly built stations, while the others are existing stations.
The Nantong Ningbo high-speed railway is an important component of China's "eight vertical and eight horizontal" high-speed railway network and coastal channels, with a very important position in the road network. After the completion of the project, it will be connected to multiple lines such as the Yancheng Nantong high-speed railway, the Beijing Shanghai high-speed railway, the Shanghai Kunming high-speed railway, the Ningbo Taizhou Wenzhou high-speed railway, and the under construction Jinhua Ningbo railway, the Shanghai Nanjing Yangtze River high-speed railway, etc., which have already been put into operation. This will promote the improvement of the road network structure in the Yangtze River Delta region, greatly facilitate the travel of people along the line, and is of great significance for promoting the integrated and high-quality development of the Yangtze River Delta.
