Method for monitoring laser collimation TBM tunnel clearance displacement

The invention discloses a laser-collimated TBM tunnel clearance displacement monitoring method which is realized by utilizing a longitudinal intervisible space between a heading machine and the circumference of a tunnel and applying the laser collimation principle to a tripod position of a vault and side walls on both sides. The invention is characterized in that: target devices are respectively arranged at the tripod position close to a cutterhead shield tail of the heading machine, a collimated laser source is arranged at the same position which has the distance L not less than 5D (tunnel diameter) behind the target devices, the collimated laser source emits reference beams emitting to the target devices, and the target devices make active homing to measure the displacement. The method can obtain maximum clearance displacement on the cross section within the range of the heading machine and the rear supporting equipment, thereby realizing the clearance displacement monitoring under the TBM construction envi