Spatiotemporal distribution and failure mechanism analyses of reservoir landslides in the Dagangshan reservoir, south-west China

Abstract

Reservoir impoundment and water fluctuations have endangered the stability of the reservoir bank slopes, which have experienced several small-scale shallow slides/collapses and few large-scale slopes with failures/deformations. Field investigations, unmanned aerial vehicle technology and site displacement monitoring dates are used to study the spatiotemporal distribution and mechanisms of the reservoir landslides within the Dagangshan reservoir. The reservoir landslides can be divided into two main types: shallow small-scale slides and unstable deformation slopes, which are clearly associated with reservoir impoundment and fluctuations of the water level. Small-scale slides/collapses are continually distributed along the river banks nearest to the water level, but deep-seated landslides have usually experienced a long history, and some obvious precursor phenomena may exist in the slopes. According to the recognition of deformational and failure evolutionary processes of large-scale slopes, and based on hydrology and geomechanics, two types of potential failure models (creep–shear–tension failure and toppling–tensile–shear model) are proposed to interpret the mechanisms of the deformation slopes in the Dagangshan reservoir. Furthermore, some preliminary discussion is presented concerning the non-significant development of landslides in the Dagangshan reservoir that are also associated with smaller water fluctuations due to the daily regulation type of the reservoir.