Abstract
Buried pipelines in permafrost regions are inevitably subjected to some typical geohazards, such as frost heave, thaw settlement and thaw slumping. The bending or/and longitudinal strains will be induced in pipe under these types ground movement, which is the potential cause of weld joint rupture. Thus, in order to prevent pipe failure, a comprehensive monitoring system was designed and used in the Mohe-Daqing oil pipeline in the permafrost region in northeast China. The Mohe-Daqing oil pipeline is built for importing oil from Russia and its north part of 440km lays in permafrost. The monitoring system includes soil temperature field monitoring system, ground displacement monitoring system and pipe strain monitoring system. The soil temperature field monitoring system, which uses fiber brag grating sensors, can monitor the distribution of surrounding soil temperature in radial direction of pipe in order to detect the change of active ring of permafrost. The ground displacement monitoring system, which is based on a total station, can discover any subsidence or heave of the pipe itself and the embankment along the pipeline. The pipe strain monitoring system, which includes pipe stress monitoring system based on fiber brag grating sensors and inertial measurement unit (IMU) mapping, can inspect the real-time change of pipe stress and the bending strain periodically respectively. Using the comprehensive monitoring system, the important parameters that affect pipeline integrity such as pipeline temperature, stress, strain and displacement of Mohe-Daqing oil pipeline can be supervised timely and effectively. And the accuracy and reliability of the monitoring system have been verified in practical application. In this paper, detail about how these systems are designed and installed on the Mohe-Daqing oil pipeline is elucidated and the monitoring data is analyzed. Through these data, the present mechanical situation of Mohe-Daqing oil pipeline is safe, but the long-term change is critical because of the soaring oil temperature that is far high than the design temperature. The monitoring system is of great significance to ensure the safe operation of Mohe-Daqing pipeline and can provide reference for the pipeline operation in permafrost areas.
The Design and Implementation of Displacement Monitoring System for Tailings Dam
