Kinematics, triggers and mechanism of Majiagou landslide based on FBG real-time monitoring

Abstract

Reservoir landslide, as one of the most serious geohazards, is worldwide distributed. To investigate its triggering factors and mechanisms that underlie its propagations, a real-time monitoring system based on Fiber Bragg Grating (FBG) technology was designed for the Majiagou landslide in the Three Gorges Reservoir (TGR) region. Through analyses of inclinometer data, it is found that there are two sliding surfaces existed in the Majiagou landslide and that the deeper sliding surface is the critical one. It accounts for nearly 80% of the deformation of the landslide. This information necessitated the recording of the displacement at the deeper sliding surface, together with the rainfall, water level, pore water pressure, temperature of the landslide using a real-time monitoring system. After analyzing the multi-parameter data in detail, it is found that observed deformation is mainly governed by reservoir water levels, while precipitation has some minor effects. The reservoir water level is the determining factor of landslide deformation when it exceeds 160 m or lower than 150 m. Whereas the reservoir water level varies from 150 m to 160 m, the fluctuation velocity plays a dominant role. The relationship between the variation of seepage field and kinematic evolution of Majiagou landslide is recognized. The average displacement rate of Majiagou landslide is within 0.1 mm/day, signifying that the landslide is still creeping presently. The results are significant with respect to stability evaluation and formulation of early warning plans for the reservoir landslide.