Nanjing Jianning West Road tunnel across the river "Innovation" off the line

Nanjing (CNA) -- The first shield tunneling machine "Chuangxin" rolled off the production line of Nanjing's Jianning West Road tunnel on Monday, marking an important milestone in the construction of the tunnel, which is the closest to the Nanjing Yangtze River Bridge. The tunnel is 2,400 meters away from the Nanjing Yangtze River Bridge and will effectively divert traffic pressure from the bridge. The cross-river section of the tunnel is 2349 meters long and the outer diameter of the segment is 14.5 meters. It is designed as a double hole with 6 lanes, which is the standard for the urban main road.

According to the introduction, the biggest difficulty of tunnel construction is that the shield machine passes through 750 meters of complex stratum, 310 meters of which are fractured zone. The stratum is soft on the top and hard on the bottom. The compressive strength of the rock reaches 125 MPa, which is one of the most difficult tunnel projects in China.

In order to overcome the difficulties, under the guidance of the expert team, the builder carefully built the shield machine, which is equipped with a retractable main drive and an atmospheric pressure cutter head, and 40 double-blade hobs are specially installed. The hob is equipped with sensing element to transmit the working status information in real time. These are the first in China's very large diameter tunnel industry.