Abstract：
The sonar method is a relative positioning measurement method for immersed elements. This method requires no survey towers and the measurement accuracy is not relative to the length of the tunnel, so the accurate position of the immersed element end can be measured efficiently. In this paper, the sonar method based real-time positioning measurement techniques are presented in terms of the element shape measurement, calibration measurement of sonar equipment position, and field positioning measurement. Based on the propagation principle of ultrasonic waves and a case study of sonar methods applied in foreign immersed tunnels, the influence on sonar accuracy by various factors is discussed. Finally, the accuracy of the sonar method based real-time positioning measurements is given.
2012, Vol. 49 