Analysis of tunnel displacement accuracy with total station

The remote distance measurement (RDM) method requires only common total stations and not special post-processing software. Moreover, this method is easy to operate and highly accurate results can be obtained. Therefore, RDM is used in the displacement monitoring of tunnel engineering. This study presents the calculation formulas for the crown settlement and wall convergence of tunnel as measured by RDM with total station. The mean error formulas are derived based on error propagation laws. When tunnel displacements measured by using total station with the ms not more than 2 mm + 2D ppm (D is the measurement distance) and mα not more than 1″, the horizontal distance between the rear viewpoint and the monitoring section is in the range of 50-150 m, the horizontal distance between the total station and the monitoring section ranges from 40 m to 60 m, and the total station is near the tunnel centerline, the measurement accuracy can reach 1 mm.