Criteria for Cutting Head Clogging Occurrence during Slurry Shield Tunneling

Cutting head clogging is more frequently encountered as more tunnels are being excavated by slurry shield machines. So establishing criteria for cutting head clogging occurrence based on the machine driving parameters is of great engineering significance. Three construction cases of the Beijing south-to-north water diversion auxiliary project, the Jinan Huanghe River Crossing tunnel construction, and the Wuhan Metro Line 8 Yangtze River Crossing tunnel construction, are introduced. Development of the main driving parameters in the construction cases, including the total thrust, the cutting head torque, the advance rate, and the cutting head rotation speed of the tunneling machines before, during, and after the cutting head clogging, are presented and analyzed. The fact is that the total thrust and the cutting head torque of tunneling machines will increase, or will not, once the cutting head clogging occurs. It is recommended to take two combined parameters of total thrust/penetration depth and cutting head torque/penetration depth into account to judge whether the cutting head clogging will occur or not. The maximum increases of the composite parameters by 2-6 times are found in the construction cases. But for the minimum increase, a 30-50% increase of the composite parameter should be noted. The findings can be of great help for similar projects.