Abstract: Using the distributed optical fiber sensing technology in landslide monitoring, the main specialty of the landside may be obtained and the monitoring efficiency may be improved. Fiber bragg grating (FBG) and brillouin optic time domain reflectometry (BOTDR) are two kinds of the most representative distributed optical fiber sensing technologies. FBG obtains the strain or the temperature by measuring the change of the reflected light wave length. BOTDR realizes the distributed temperature and strain measurement by measuring the shift size of backward Brillouin scattered light. The sensitivity of FBG sensor is high but it only measured the discrete distributed sensing spots. The BOTDR sensing part is the optical fiber. It may realize the long distance, the uninterrupted and distributed monitor. But for its technical limit, the measurement distance resolution of BOTDR is not high. Based on this, the authors put forward a notion, that BOTDR combines with FBG to monitor landslide. In Canlian landslide located in Wushan, the monitoring optical fiber was laid on the entire landside and BOTDR was used to obtain the outline information of it. FBG was installed at the certain essential spots, the strain fissures, to obtain their strain information. Thus the landside can be monitored from dot to line and future to surface. Finally the completed strain information of the landslide can be obtained.

Key words: FBG, BOTDR, strain, landslide monitoring