乌长高速卫城滑坡发育特征与成因机制探讨

Analysis on the development characteristics and genetic mechanisms of the Weicheng Landslide along Wu-Chang Expressway

摘要

【目的】乌长高速(乌当—长顺)卫城滑坡为堆载和降雨诱发的大型堆积体滑坡，滑坡对猫跳河下游水利水电工程安全运营构成威胁，亟需揭示堆载-降雨耦合作用下该滑坡的发育特征及成因机制。【方法】采用地质调查、现场监测、钻探及数值模拟等手段，阐明了滑坡的物质成分及发育特征，分析了天然状态、堆载、堆载+降雨作用下滑坡的位移场、剪切带、滑带有效应力状态及稳定性，归纳了滑坡的主要致灾因子及其成因机制。【结果】结果表明：该滑坡在天然状态与堆载作用下分别处于稳定与基本稳定状态，堆载+降雨作用下处于欠稳定状态，且出现整体变形迹象；在堆载和降雨叠加作用下，位移场逐步增大，剪切带特征逐渐显著，滑带有效应力呈先增加后减小的变化趋势，稳定性不断降低。【结论】堆载-降雨耦合作用下该滑坡的破坏模式为后推移-前牵引式，地形地貌及地层岩性为滑坡发育的地质条件，后缘堆载为滑坡的孕育条件，强降雨为滑坡的主要诱发因素。研究成果可为乌长高速卫城滑坡防治设计提供指导，也为降雨-堆载诱发型堆积体滑坡科学防治提供借鉴。

Abstract

[Objective] The large-scale accumulation landslide induced by loading and rainfall effects located in Weicheng Town, Guiyang City, Guizhou Province, China. The landslide poses a threat to the safe operation of the hydropower and water conservancy projects downstream of the Maotiao River. It is crucial to reveal the developmental characteristics and genetic mechanisms of the landslide under the coupling effect of loading and rainfall. [Methods] A combination of geological surveys, field monitoring, drilling and numerical simulations was employed. These method were used to elucidate the material composition and developmental characteristics of the landslide. Additionally, the displacement field, shear band characteristics, effective stress state of the slip zone, and slope stability under natural conditions, loading, and the combined effects of loading and rainfall are analyzed. The primary triggering factors and genetic mechanisms of the landslide were systematically summarized. [Results] The results show that the landslide is in a stable state under natural conditions and a marginally stable state under loading conditions. However, under the combined effects of loading and rainfall, it transitions to an unstable state, exhibiting signs of overall deformation. Under the combined effects of loading and rainfall, the displacement field progressively increases, shear band characteristics become more pronounced, and the effective stress in the slip zone initially increases but subsequently decreases, leading to a continuous reduction in stability. [Conclusion] The failure mode of the landslide under the coupling effect of loading and rainfall is characterized by backward pushing and forward traction. The topography, geomorphology, and lithology of the strata constitute the geological conditions for the development of the landslide. Rear-edge loading serves as the preparatory condition, while intense rainfall acts as the primary triggering factor for the landslide. Our findings provide guidance for the prevention and control design of Weicheng landslide along Wu-Chang Expressway and offer reference for the prevention and control of accumulation landslides induced by loading and rainfall effects.

关键词

乌长高速 / 堆积体滑坡 / 堆载 / 降雨 / 数值模拟 / 成因机制 / 剪切带 / 稳定性

Key words

Wu-Chang Expressway / accumulation landslide / loading / rainfall / numerical simulation / genetic mechanism / shear band / stability

基金资助

国家重点研发计划项目(2023YFC3008400)

陕西省科技创新团队项目(2021TD-51)