基于GDEM-GAVA的白羊城沟泥石流成灾风险数值分析

NUMERICAL ANALYSIS OF MUDFLOW RISK IN BAIYANGCHENG GULLY BASED ON GDEM–GAVA

降雨型泥石流是一个降雨-洪水-泥沙输运-推移质运动的多过程耦合过程。本文借助颗粒碎屑流仿真系统(GDEM-GAVA),对白羊城沟泥石流的成灾风险进行了分析。首先通过历史灾情数据反分析出了沟道物源的力学参数,而后基于该参数分析了不同降雨强度下该泥石流的成灾临界降雨时长。计算结果表明,白羊城沟泥石流物源的饱和黏聚力为0.5~1 kPa,饱和内摩擦角为5°~10°;降雨强度为65 mm/h时,沟道形成泥石流的时间为3.6 h;降雨强度为78 mm/h时,沟道形成泥石流的时间为2.8 h;降雨强度为88 mm/h时,沟道形成泥石流的时间为2.3 h。上述泥石流成灾风险的分析结果可为白羊城沟泥石流的科学预警提供必要的依据。

Rainfall debris flow is a multi-coupling process including rainfall–flood–sediment transport–bed load movement.The disaster risk of Baiyangcheng Gully debris flow is analyzed based on GDEM–GAVA software.First,through historical disaster data,the accurate mechanical parameters of the channel material source are back-analyzed.Then,based on the parameters obtained from the inversion,the critical rainfall duration of the debris flow under different rainfall intensities is analyzed.The calculation results showed that the saturated cohesive force of the debris flow in Baiyangcheng Gully is 0.5~1 kPa,and the saturated internal friction angle is 5°~10°;when the rainfall intensity is 65 mm/h,the formation time of the debris flow in the channel is 3.6 h;when the rainfall intensity is 78 mm/h,the formation time of the debris flow in the channel is 2.8 h;when the rainfall intensity is 88 mm/h,the formation time of the debris flow in the channel is 2.3 h.The analysis results of the above-mentioned debris flow disaster risk can provide the necessary basis for the scientific early warning of the Baiyangcheng Gully debris flow.