Abstract: Traditional posture measurement of subway shield has the disadvantage of long operation time, cross operation with the construction line, a large amount of labor, and the unavailability of real-time measurement. In this paper, the method of close-range photogrammetry is used to measure the shield segment posture. The artificial marks are laid on the shield ring to make digital camera shoot, and the flux of light method is used to process data solution for shot pictures. Finally, the coordinate of the shield ring's center point is determined based on the space three-point determination of the circle center after getting the coordinate of the signalized point. The experimental results show that the error of the traditional measurement method is within 3 cm, which can completely meet the measurement accuracy requirement of the shield segment's posture, with good promotion value and economic benefits.

Key words: subway, shield tube attitude measurement, close range photogrammetry, digital camera