浅层地下水及水文过程对黄土液化流滑场地的影响研究

    STUDY ON THE INFLUENCE OF SHALLOW GROUNDWATER AND HYDROLOGICAL PROCESSES ON LOESS LIQUEFACTION AND MUD FLOW SITES

    • 摘要: 含水特征是黄土地震液化的必要条件之一,地下水及其分布条件在黄土液化失稳中通常起着决定性作用。本文基于1 m地温法对永光村地震液化场地的浅层地下水分布及浅层地下水脉流流向进行探测,并结合水文分析、地形趋势分析及地形湿度指数探讨永光村地质灾害的发生与浅层地下水分布、降雨汇流之间的关系。通过钻孔数据与高密度电法结果对1 m地温法探测结果进行验证,表明1 m地温法在黄土液化场地可以有效探测浅层地下水脉。研究结果表明永光村的浅层地下水脉流动路径有3条,主要由地势较高的北部流向西南冲沟方向。通过震前地形趋势分析与地形湿度指数(Topographic Wetness Index,TWI)计算发现永光村西滑坡(黄土液化流滑)具有更大的坡面汇流面积,是更易受区域地形影响的蓄积区域,因而导致了此处丰富的地下水。震后TWI值与1 m地温法对比表明:TWI高值大块且集中分布的范围反映了研究区浅层地下水较为丰富的区域。因此,浅层地下水脉发育与降雨产生的径流汇集导致的地下水水位上升是黄土液化致灾的重要原因。

       

      Abstract: Water content is a critical prerequisite for loess liquefaction,and groundwater usually plays a decisive role in the instability of loess liquefaction. This study explores the distribution of shallow groundwater and its flow direction at the Yongguang Village liquefaction site using the 1 m ground temperature method. Hydrological analysis,topographical trend analysis,and the Topographic Wetness Index(TWI)were used to explore the relationship between geological disasters in Yongguang Village and shallow groundwater distribution and rainfall runoff. Validation through drilling data and results from high-density electrical methods has confirmed the effectiveness of 1-meter ground temperature measurements for identifying shallow groundwater veins in areas prone to loess liquefaction. The study identifies three main flow paths of shallow groundwater in Yongguang Village,with the flow direction ranging from the northern part of the higher terrain to the southwestern gully. Pre-earthquake topographical trend analysis and TWI calculations reveal that the western landslide of Yongguang Village(loess liquefaction flow slide) has a larger slope runoff area,making it more susceptible to regional topography and thus groundwater enrichment. Post-earthquake comparisons between TWI values and the 1-meter ground temperature method reveal that areas with high and concentrated TWI values correspond to regions in the study area with abundant shallow groundwater. Therefore,the development of shallow groundwater veins and the accumulation of runoff from rainfall,resulting in rising groundwater levels,are crucial causes of loess liquefaction disasters.

       

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