沟道型滑坡-碎屑流运动距离经验预测模型研究

EMPIRICAL PREDICTION MODEL FOR MOVEMENT DISTANCE OF GULLY-TYPE ROCK AVALANCHES

沟道型滑坡-碎屑流具有隐蔽性强、危险性高、力学机理复杂的特点,研究其运动距离预测模型具有重要的理论意义和实践意义。本文基于遥感GIS技术,结合野外调查,获取了汶川地震触发的38个沟道型滑坡-碎屑流的基础数据。通过相关性分析确定沟道型滑坡-碎屑流最大水平运动距离L的影响因素从大到小依次是滑坡体积V、最大垂直运动距离H、滑源区高差Hs、沟道段坡度β。采用逐步回归方法建立了滑坡-碎屑流最大水平运动距离L的最优多元回归模型,检验结果表明模型具有较高精度。将最优多元回归模型与国际上应用较多的滑坡运动距离和泥石流运动距离预测模型进行对比,表明考虑滑坡体积、地形落差和沟道段坡度的运动距离预测指标体系,具有最高的拟合优度和较好的物理含义,可为沟谷山区滑坡-碎屑流危险性评价提供参考依据。

Prediction model for movement distance of rock avalanches has important theoretical significance and practical significance due to the characteristic of difficult detection,complex mechanism and high risk of gully-type rock avalanches. This study selects 38 typical rock avalanches induced by Wenchuan earthquake,and obtains their basic data based on the remote sensing and GIS technology combining with field investigation. Through correlation analysis,the results indicate that the influence factors of the maximum horizontal movement distance of rock avalanches（ L） are landslide volume（ V）,the maximum vertical movement distance H,the elevation difference of slip source area（ Hs）,and the mean slope angle of the lower channel（ β）. Then a stepwise regression method is adapted to build optimal multiple regression model for the prediction of L. The validation shows that the multiple regression model is suitable for predicting rock avalanche hazardous zones in Wenchuan earthquake areas. The optimal multiple regression model and other internationally common- used prediction models are compared for the movement distance of landslides and debris flows. The result indicates that the forecast index system is suitable for the rock avalanches risk assessment in mountainous areas. The system considers the volume,drop height,the meanslope of the channel,with better goodness of fit index and physical meaning.