Study on deformation mechanism and warning model of step-like landslide in Three Gorges Reservoir area

doi:10.11947/j.AGCS.2022.20220296

Abstract

Abstract: Since the impoundment in 2003, more than 5000 landslides or potential landslides have been identified in the Three Gorges Reservoir area, and these hazards seriously threaten the continued operation of the Three Gorges Reservoir and the safety of dams, waterways, and residents. By studying the deformation characteristics, inducing triggering factors, and instability mechanism of landslides, it is helpful to evaluate the stability of landslides and construct early warning and prediction models. Taking the Bazimen Landslide in the Three Gorges Reservoir Area as an example, the deformation characteristics and instability mechanism of the landslide are studied by comprehensively analyzing the data of rainfall, reservoir water level, manual and automatic GNSS monitoring, combined with the field macro inspection and exploration data, and the reasonable early warning criterion and threshold are determined. The research shows that: ① The overall deformation of the Bazimen landslide is obvious and in the creep deformation stage. The landslide deformation is mainly concentrated in May to September every year, and the landslide accumulation curve presents typical “step-like” deformation characteristics. ② The deformation of landslides is controlled by slope structure, lithology, and other factors. The decline of reservoir water level is the main driving factor of landslide deformation and is positively correlated with the decline rate of reservoir water. In addition, severe rainstorms and continuous rainfall will promote landslide deformation in the stage of water-level decline, reservoir low water level operation, and water level rise, which is the second driving factor of landslide. ③ The threshold displacement rate for step-like deformation of Bazimen Landslide is 4.6 mm/d, the threshold of 7d cumulative rainfall is 60 mm, the threshold of reservoir water level is 159 m, and the threshold of reservoir water level decline rate is 0.4 m/d, obtained by refined data analysis and improved tangent angle method.

Key words: Bazimen landslide, step, reservoir water level, deformation mechanism, warning model

CLC Number:

P228

GUO Fei, HUANG Xiaohu, DENG Maolin, YI Qinglin, ZHANG Peng, CHEN Jianwei, CHEN Lujun. Study on deformation mechanism and warning model of step-like landslide in Three Gorges Reservoir area[J]. Acta Geodaetica et Cartographica Sinica, 2022, 51(10): 2205-2215.

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