基于Fredlund&Xing模型的渗流分析在川东红层梯田滑坡中的应用

Application of seepage analyses based on Fredlund&Xing model in red beds terrace landslides in eastern Sichuan

四川省巴中市通江县新场镇七家沟村二社水头上滑坡为川东典型红层梯田滑坡,区内类似斜坡覆盖范围广泛,但针对该地区此类滑坡的渗流分析研究较少。在对滑坡区进行大量野外调查、勘查、资料收集的基础上,综合运用卫星遥感、无人机航拍、机载LiDAR、室内试验等技术手段,基于Fredlund&Xing土水特征曲线数学模型,采用Geo-Studio中SEEP/W模块进行渗流分析,将不同时间阶段分析结果与SLOPE/W模块耦合,继而得到稳定系数与降雨、时间之间的动态变化关系,揭示了滑坡的变形过程和形成机理。研究显示:(1)连续降雨促使坡体地下水位升高,稳定性降低,最终导致水头上滑坡整体失稳破坏;(2)滑坡变形过程、地下水出露特征与Geo-Studio计算结果基本吻合,说明基于Fredlund&Xing数值模拟在类似地区能提供较为准确的模拟结果;(3)开垦梯田(水田)会降低坡体稳定性。研究结果可为四川山区类似滑坡灾害进行隐患排查和主动防范提供理论支撑,为防灾减灾提供参考依据。

The Shuitoushang landslide in Ershe in Qijiagou Village of Xinchang Town in Tongjiang County is a typical red-bed terrace landslide in eastern Sichuan.There are few studies on the seepage analyses of such landslides in this area,but similar slopes are widely distributed in the area.In this paper,on the basis of a large number of field investigations,surveys and data collection of disaster sites,the satellite remote sensing,UAV aerial photography,airborne LiDAR,indoor tests and other technical means are comprehensively used to analysis the landslide.Based on the mathematical model of Fredlund&Xing soil-water characteristic curve,the SEEP/W module in Geo-Studio is used to conduct the seepage analysis,and the analysis results at different time stages are coupled with the SLOPE/W module.Then the dynamic relationship between the stability coefficient,rainfall and time is obtained,revealing the deformation process and formation mechanism of the landslide.The results show that:(1)the continuous rainfall causes the groundwater level to rise and the slope stability to decrease,eventually leading to the overall instability and failure of the Shuitoushang landslide.(2)The deformation process of the landslide and the characteristics of groundwater exposure are basically consistent with the results calculated by Geo-Studio,indicating that the results based on Fredlund&Xing model can provide more accurate simulation results in similar areas.(3)Reclamation of terraced fields(paddy fields)will reduce slope stability.The results can provide theoretical support for hidden danger investigation and active prevention of similar landslide disasters in mountainous areas of Sichuan,and provide a reference for disaster prevention and mitigation.