基于“阶跃”变形特征的降雨型滑坡预警判据探讨

Preliminary analysis on rainfall thresholds for early warning of the rainfall induced landslides based on“step”deformation characteristics

由于滑坡灾害的发生具有随机性和复杂性,经常给人们生活造成严重的经济损失,甚至威胁生命安全,故建立滑坡预警判据及模型是减小损失的重要手段。文章首先确定了有效降雨量-变形速率-改进切线角为降雨型阶跃滑坡的预警关键判据。然后运用斜率单变点法确定滑坡“阶跃”变形曲线上的“破坏拐点”和“稳定拐点”并提取变形加速区间的详细信息,以此求解有效降雨量-变形速率-改进切线角综合预警判据阈值。最后,结合麻池村1号滑坡各发展阶段宏观变形特征,将时空演化规律有机结合,建立了4级递进式综合判据分级预警模型。结果表明:麻池村1号滑坡的运移形式为牵引式,在降雨因素的激发下,累计位移曲线呈典型的“阶跃”变形特征;麻池村1号滑坡变形受前期降雨影响,前期降雨与当期降雨组成一个降雨过程的时间间隔阈值为10 d,“前期+当期降雨”模式下对应的降雨阈值分别为24 mm、32 mm;基于监测数据精细化分析以及改进切线角法获取的麻池村1号滑坡的位移速率阈值为12 mm/d。研究可为此类型滑坡灾害的预警提供理论基础和技术指导。

Since the occurrence of landslide disasters is random and complex,which often causes serious economic losses to people's lives and even threatens life safety,establishing landslide early warning criteria and models is an important means to reduce losses.In this paper,the effective rainfall-deformation rate-improved tangent angle is determined as the key criterion for the early warning of rainfall-type step landslide.Then,the slope single-variable point method is applied to determine the“damage inflection point”and“stability inflection point”on the landslide“step”deformation curve to extract detailed information of the deformation acceleration interval,so as to solve the effective The threshold value of rainfall-deformation rate-improved tangent angle integrated warning criterion.Finally,a 4-stage progressive integrated warning model was established by combining the macroscopic deformation characteristics of the landslide at each stage of development and the spatial and temporal evolution laws.The results show that the transport form of landslide No.1 in Machi Village is traction type,and the cumulative displacement curve shows typical“step”deformation characteristics under the excitation of rainfall factors.The deformation of landslide No.1 in Machi village is affected by the early rainfall,and the time interval threshold between the early rainfall and the current rainfall is 10 d,and the corresponding rainfall thresholds in the“early+current rainfall”mode are 24 mm and 32 mm respectively.The study can provide theoretical basis and technical guidance for early warning of this type of landslide hazard.