散粒体滑坡涌浪运动特征与能量转化规律研究

A study of the kinematic characteristics and energy conversion of waves generated by granular landslide

滑坡涌浪灾害造成的伤亡和损失一般远超滑坡灾害本身,已引起广泛关注。针对该类灾害的预测评价一直是研究的难点,精细刻画滑坡涌浪运动特征和能量转化规律是解决问题的关键和前提。因此,以天然碎石模拟散粒体滑坡,建立缩尺的矩形水槽滑坡涌浪三维物理试验模型,研究滑坡体积、速度和水深对堆积体形态和涌浪特征的影响以及滑体与水体能量转化规律。研究结论包括:(1)滑体通过冲击、挤压和抬升水体形成涌浪的特征受滑体规模和形态影响显著;厚度大且速度快的滑体趋向产生非线性过渡波,厚度小且速度低的滑体一般产生非线性震荡波;(2)基于试验提出的体积效应和速度效应揭示了一定水深的涌浪规模与滑坡体积和速度呈正相关规律,水深效应则解释了一定波能的涌浪在波形和速度上的分布差异,结果表明浅水比深水工况涌浪高度平均高出67%、波速平均高出51.17%;(3)基于试验的数值反演总结了滑体势能与波能转化率为1.00%~3.07%,由于三维试验中滑体与水体在水平和环向的扩散造成更多能量耗散,相较二维试验转化率较低。通过探讨散粒体滑坡运动过程和首浪产生、传播及爬高特征,揭示滑体-水体能量转化基本规律,研究成果对滑坡涌浪防灾减灾工作具有一定的理论价值和意义。

The consequences of landslide waves are far beyond the landslide itself that has attracted widespread attention.The prediction and evaluation of this kind of disaster has always been difficult,and the precise description of landslide surge motion characteristics and energy conversion law is the key and premise to solve the problem.In this paper,we use gravel to mimic granular landslide and establish a 3D landslide wave model in a rectangular flume,aiming to analyze how the landslide volume,velocity and water depth affect landslide accumulation,wave characteristics and energy conversion.The results show that(1)the waves generated by solid impacting the water are affected by the landslide size and shape.Slides with larger thickness and faster speed tend to produce nonlinear transition wave,and thin and slow slides generally produce nonlinear oscillation wave.(2)The volume effect and velocity effect based on the test reveal that the surge scale of a certain water depth is positively correlated with the landslide volume and velocity.The water depth effect explains the differences of waveform and velocity under a certain wave energy.Statistic results show that under the shallow water conditions,surge height on average is 67%higher and wave speed on average is 51.17%higher than those under the deep water conditions.(3)The conversion rate between landslide energy and wave energy ranges from 1.00%to 3.07%.3D experiments encounter more energy dissipation due to diffusion and its conversion rate is lower than that in the 2D experiments.This study discusses the kinematic characteristics of granular landslide,first wave generation,propagation and inundation,and proposes the basic law of energy conversion between landslide and water.It id of certain value and significance for landslide wave hazard prevention and mitigation.