滑坡堵江成坝的形成演进机制及危险性预测方法研究进展

Research progress on the formation mechanism and risk assessment method of river blocking induced by landslide

近年来,频发的地震活动和极端天气诱发了大量滑坡堵江,严重威胁所在流域人民生命财产和基础设施安全,而目前对滑坡堵江成坝的形成演进机制认识仍不够全面,值得进一步深化研究。梳理21世纪以来典型的滑坡堵江案例,分析其中危险性较大的堰塞坝形成的一般过程和主要特征;针对大型的岩体滑坡堵江,分别从理论分析、物理模型试验和数值模拟方法3个方面揭示其成坝的必要条件和堵江过程的流固耦合细观机制;提出滑坡堵江危险性预测的3阶段:即堵江状态预测、堰塞坝稳定性预测和溃坝危险性预测等。通过全面梳理堵江危险性预测3阶段研究成果发现,堵江状态预测参数和标准选取尚没有统一形式,堰塞坝稳定性评价尚未考虑坝体材料和结构等特征,溃坝危险性预测的数学模型物理机制仍有待进一步揭示。基于当前研究存在的局限性,凝炼滑坡堵江研究未来应重点关注的4个问题:(1)考虑碎裂化过程的崩滑体堵江堆积结构及成坝预测模型;(2)滑坡堵江成坝演进过程的物理和数值模拟方法;(3)基于滑坡物源状态的堵江危险性评价方法与风险评估;(4)堰塞坝临灾预警因子及监测预警关键技术。研究成果为高山峡谷地区滑坡堵江灾害链预测、堰塞坝应急抢险地质处置及区域防灾减灾规划提供有益参考。

In recent years,a large number of landslides blocking rivers induced by earthquake and extreme climate occurred frequently,seriously threatening the safety of people's life and property and infrastructure in the basin.However,the current understanding of the formation mechanism of landslides blocking river is still not comprehensive,which is worth further research.Based on typical cases of landslide blocking river since the 21st century,the general process and main characteristics of landslide blocking river are deeply analyzed.In view of large scale of landslide blocking river,the necessary conditions for the formation of landslide river blocking and the meso-mechanism of fluid-soil coupling in the process of river blocking are revealed from three aspects of theoretical analysis,physical model test and numerical simulation respectively.Hazard assessment of landslide blocking river mainly include distinguishing of river blocking,evaluation of the landslide dam stability and assessment of dam failure hazard.However,there is no unified standard form for distinguishing of river blocking.The material and structure characteristics of the landslide dam have not been considered in the stability evaluation of the dam.The physical mechanism of the mathematical model for predicting peak discharge of dam-break flood still needs to be further revealed.Based on the limitations of the current research,four key issues that should be focused on in the study of landslide blocking river are prospected:(1)Study on the accumulation structure and prediction model of landslide damming induced by debris-avalanche considering the influence of fragmentation;(2)Physical and numerical simulation methods of evolution process of landslide blocking river;(3)Hazard assessment method of landslide blocking river based on the state of landslide material;(4)Early warning factors and key monitoring and early warning technologies for landslide dams.The results provide useful reference for the prediction of landslide blocking river disaster chain,emergency geological treatment of landslide dam and regional disaster prevention and mitigation planning in mountain and ravine region.