基于滑面分区段力学模型的高速滑坡运动过程能量转化研究

Energy conversion of the high-speed landslide movement process based on a sliding surface partition mechanical model

高速滑坡具有运动速度快、波及范围广的灾害特征,因此对滑坡启动、加速和静止整个运动过程进行研究很有必要。基于滑面力学特性将滑面分为弹性介质区和应变弱化区,构建了高速滑坡二维力学模型,提出了滑坡启动动能计算公式和滑坡运动过程的能量计算公式;以千将坪滑坡为例,采用启动动能计算公式得出滑坡的启动速度为2.35 m/s;依据滑面形态将其运动轨迹划分为快速加速、平稳加速、平稳减速、急剧减速4个阶段,进行运动过程分析,得出滑坡最大速度为16.8 m/s,以滑坡前缘高程所在平面为势能基准面,分析不同能量与总能量占比的变化情况,在滑坡的4个运动阶段中,动能占比分别为9.1%,25.6%,15.1%,0%;摩擦损耗能量占比分别为:5.5%,58.8%,81.7%,95.5%;势能占比分别为:85.2%,14.2%,0%,0%;其他阻力能耗占比分别为:0.2%,1.4%,3.2%,4.5%。研究结论对高速滑坡致灾机制和风险分析具有重要意义。

High-speed landslides have the characteristics of fast movement speed and rapid spread.Therefore,it is necessary to study the whole movement process of landslides starting,accelerating and resting.Based on the mechanical properties of the sliding surface,the sliding surface is divided into an elastic medium region and a strain weakening region,and a two-dimensional mechanical model of a high-speed landslide is constructed.The energy calculation formulas of landslide initiation and landslide movement processes are proposed.Taking the Qianjiangping landslide as an example,the initiation speed of the landslide is 2.35 m/s by using the energy calculation formula of landslide initiation.According to the sliding surface morphology,the landslide movement trajectory can be divided into a fast acceleration stage,a steady acceleration stage,a steady deceleration stage,and a sharp deceleration stage.The maximum speed is 16.8 m/s during analysing the motion process.The elevation plane of the landslide front is taken as the potential energy datum plane to analyze the variation in different energy and total energy ratios.In the four movement stages of the landslide,the proportions of kinetic energy were 9.1%,25.6%,15.1%,and 0%;the proportions of friction loss energy were 5.5%,58.8%,81.7%,and 95.5%;the proportions of potential energy were 85.2%,14.2%,0%,and 0%;and the proportions of other resistance energy consumption were 0.2%,1.4%,3.2%,and 4.5%.The research conclusions are of great significance to the hazard mechanism and risk analysis of high-speed landslides.