Abstract:

The shield tunnel excavation tunnel is mainly divided into two major processes: tunnel excavation and segment assembly.In the process of segment assembly, the host machine of the shield is at a standstill. In this process, the overall sinking and head felling of the host machine may appear.In order to avoid the phenomena, it is necessary to make a prediction on sinking size and head fellingsize of the host machine, and adjust the attitude in advance at the end of the tunneling process of the shield machine.In the static process of the shield machine, the sinking size and the head felling sizeare exactly offset by the amount of posture adjustment, so it can ensure the tunnel axis is consistent with the design axis.In this paper, the water and soil pressure around the shield and the reaction force of the foundation to the shield machine are analyzed and calculated.The Matlab software is used to model and analyze four different stratum, and the sinking and head fellingsize planting of the shield mainframe in each layer are obtained.Through calculation, in the shield tunneling section of the Soviet Union cross sea passage project,the host machine has the largest change in posture in soft soil such as silty soil, the maximum head felling amount is about 0.38 m, and the overall sinking is about 0.12 m; in the dense medium coarse sand stratum, the attitude change is the smallest, and the maximum heading amount is about 0.13 m.The overall sinking is about 0.04 m. The range of the amount of the head felling and the amount of sinking is obtained, thereby realizing the advance adjustment of the attitude of the shield machine.

Key words: shield machine, host standstill, host machine sinking, head felling, shield load, sinking size, head felling size, preventive measures