The city of Nanjing is building a new crossing of the Yangtze River with the "Jianning West Road Tunnel". The connection is being built between Xingpu Road and Jiangbei Avenue in Jiangbei New District and Jinchuan River West Road over a distance of 6,801 meters. The total length of the twin-tube tunnel section is 3,550 meters. Two Herrenknecht Mixshields with an impressive diameter of 15.02 meters excavated a total of 4,711 meters of tunnel.
The two machines left the Nansha plant in March and June 2021. Both successfully completed the tunnel drive in October and December 2023.
Water pressures of up to 7.7 bar and a minimum overburden of 10.4 meters posed a challenge for the machines. In addition, obstacles such as composite layers of hard and soft material had to be overcome. On both sides of the Yangtze, impacts - such as settlements - on the dams, residential buildings, cultural monuments, roads and metro lines had to be strictly avoided. Guidance systems from VMT supported an ideal shield position and navigated the machines safely through the complex subsoil.
Among other things, extra-resistant cutting tools were chosen for this. However, the machines encountered heavily to moderately weathered dolomite with strengths of between 30.4 and 125.5 MPa, particularly on the southern bank. Quartz-containing gravel layers at shallow depths were a challenge not only for the tools but also for the hose lines.
