考虑时间滞后效应的库岸滑坡位移预测

A Prediction Model of Landslide Displacement in Reservoir Area Considering Time Lag Effect

  • 摘要: 在库区滑坡位移预测预报研究中,库水位响应的滞后性使得传统滑坡位移预测模型难以分析单调增长的阶跃式变形特征,严重影响预测结果。基于此,在考虑库水位时间滞后效应基础上,建立了一套可应用于工程现场的自回归分布滞后位移预测模型,并在金沙江上游某库岸滑坡进行工程应用。工程研究案例得出,库水位上升、地震是该滑坡变形加剧的主要诱发因素,且库水位作用于滑坡变形的滞后天数为8天,新模型计算滑坡累积位移与实际位移相关系数高达0.992 7,均方根误差为14.11 mm。此外,通过计算趋势速率比指标可以为滑坡监测预警提供新的敏感性评价参量。该研究不仅建立了一套具有物理意义的库岸滑坡位移预测模型,实现了滑坡位移的综合分析,而且实现了地震对滑坡位移演化贡献的定量计算,为蓄水期库岸滑坡演化全过程的安全风险管理提供了新的技术支持。

     

    Abstract:
    Objectives In the research work of reservoir landslide displacement prediction, due to the lag of reservoir water level response, it is difficult for the traditional landslide displacement prediction model to analyze the monotonically increasing step deformation characteristics, which seriously affects the prediction results, and it is necessary to establish a landslide displacement prediction model that can consider the time lag effect.
    Methods We analyze the time lag effect of reservoir levels separately through grey correlation, account for the cumulative effect of earlier rainfall, and consider the effect of earthquake on landslide deformation, and establishe an autoregressive distributed lag landslide displacement prediction model that can be applied to engineering sites.
    Results The results show that: (1) The engineering case study concluded that rising reservoir levels and earthquakes were the main triggering factors for the increased deformation of the landslide, and the lag time of reservoir levels acting on landslide deformation was 8 days. (2) The correlation coefficient between the cumulative landslide displacement and the actual displacement calculated by the new model is as high as 0.992 7, with a root mean square error of 14.11 mm. (3) The calculation of trend speed ratio indicators can provide a new sensitivity evaluation parameter for landslide monitoring and early warning.
    Conclusions The study establishes a physically significant prediction model for reservoir bank landslide displacements, provides a comprehensive analysis of landslide displacements, achieves a quantitative calculation of the seismic contribution to landslide displacement evolution, and provides new technical support for the safety risk management of the whole process of reservoir bank landslide evolution during the water storage period.

     

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