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沟谷型剧动式滑坡以其启程剧动、高速短程、灾害链生效应等特点在深切峡谷地区具有极高的潜在风险。以拉月滑坡为例,基于滑坡堵江动力学过程,首先分析沟谷型滑坡的变形破坏机制与灾害链成灾模式,将拉月滑坡灾害链全过程概括为:节理化边坡地震降雨协同劣化→倾倒拉裂模式下变形发展→剪出口锁固段破裂牵连坡体高位剪出→碰撞解体并碎石流化→刨蚀河床并阻塞堆积→堰塞堵江。然后针对沟谷型滑坡堵江灾害高速短程的特点,提出滑坡强度(规模、速度和滑距)为堵江灾害的主控因素,而水沙运动规律则为影响因素。在此基础上,采用层次分析法确定各致灾因素的权重作用,并建立沟谷型滑坡堵江危险性判别模型表达式。最后通过典型案例计算表明,该模型较好地反映了沟谷型剧动式滑坡堵江的特点,对今后沟谷山区工程建设所遭遇的滑坡堵江灾害预测和风险调控,防灾减灾具有指导意义。
Gully dramatic landslide with its opening drama, high-speed short-range, disaster chain effect and other characteristics in the deep canyon region has a very high potential risk. Taking Lala landslide as an example, based on the dynamic process of landslide plugging, the deformation and damage mechanism of the valley landslide and the hazard model of disaster chain are firstly analyzed. The whole process of the disaster chain of Lala moon landslide is summarized as follows: → Deformation and development under the mode of tipping and fissuring → The fracture of the shear section at the shear outlet implicates the high shear of the slope body → the collision disintegrates and the lithosphere is fluidized → the river bed is obstructed and the accumulation is blocked → the dam is blocked and the river is blocked. Then, according to the characteristics of the high-speed and short-range damage in the valley-type landslide, it is proposed that the landslide intensity (scale, speed and sliding distance) is the main controlling factor of the dam-stopping disaster, while the law of water and sediment movement is the influencing factor. On this basis, the analytic hierarchy process is used to determine the weight effect of each disaster-causing factor, and the expression of hazard discrimination model of the ditch-shaped landslide is established. Finally, a typical case calculation shows that the model can better reflect the characteristics of the drastic landslide plugging in the valleys. It is of guiding significance for disaster prediction, risk control and disaster prevention and mitigation of landslide plugging encountered in construction of mountainous valleys in the future.