Investigation of settlement monitoring method based on distributed Brillouin fiber optical sensor

Abstract

Subgrade is the base of bearing the weight of track structure and train load, and is also the most unstable link in the track under various adverse factors such as soil cave collapse and earthquakes. The subgrade settlement should be routinely monitored to improve the safety and lower the risk of train derailment. In this paper, subgrade settlement monitoring method using distributed Brillouin fiber optical sensor is proposed. In order to obtain the displacement quantity from the measured strain or Brillouin frequency shift, strain accumulative integral method for the settlement calculation was studied. A comparison study between the measured displacement from the proposed method and those from manual measurement is constructed. The test results show that the strain accumulative integral method based on the distributed Brillouin optical fiber monitoring stain data can effectively measure the settlement of subgrade.