地震涌浪及冰碛堰塞湖溃决机理

The number of glacier lake outbursts has been increasing in high altitude and intense seismic mountain areas, with the global warming and glacial retreat in recent years. In Wenchuan earthquake; it was showed that the intensity of surges in lakes induced by the earthquake could be larger than the critical hydrological conditions of glacier dam outburst. However, the damage of the earthquake-induced surge has been ignored in the screening for risk resources of dammed lake outburst. Based on the hypothesis of surge energy from lake basin shaking, N-S equation as the control formula, dynamic equations computing surge velocity field and wave altitude is proposed. Earthquake waves are independent variables, and dammed lake water’s characteristics are initial conditions. Theoretical formulas are verified by experiment of simulation waves of earthquake-induced surge on large scale shaking table. Based on self-organized criticality theory, wave flume experiments are utilized to research the starting process of dam particles and the macro dynamic performance under multi-surges. Hydrology criterions of earthquake surges induced by the overflow dammed lake outburst, characteristic of possibility, are proposed. The dynamic water pressure derived by earthquake surge model is used to research the instability mechanism of the whole dammed lake under earthquakes as well as dynamic water pressure. The risk assessment of glacier dammed lake outburst under earthquake is proposed, as the example of Sichuan-Tibet rail. Achievements can provide scientific basis for the risk control of national key projects in high altitude and intense seismic mountain areas. The model of surge induced by earthquake is creative.

近年来随着全球气候变暖和冰川退缩,高寒强震山区冰碛湖溃决有增多的趋势。汶川地震表明，地震引发库湖水体涌浪的强度，可能超过冰碛坝溃决的临界水文条件，但目前对堰塞湖溃决风险源的排查中，一直忽视了地震涌浪的危害作用。基于涌浪能量来自于湖盆振动的假说，以严格的N-S方程作为控制方程，建立以地震波为自变量、堰塞湖水体特征为初始条件，计算湖水涌浪流速势和波面高程的动力学方程，并通过地震涌浪大型振动台造波模拟实验，对理论公式进行修正和检验；基于自组织临界状态理论，利用波流水槽实验，研究多阵涌浪扰动下坝体颗粒启动过程以及宏观动力学行为，建立地震涌浪作用下堰塞坝溢流型溃决概率的水文判据；利用地震涌浪模型计算动水压力，研究地震振动与动水压力综合作用下的堰塞坝整体失稳机理；以川藏铁路为例，提出地震作用下冰碛堰塞湖溃决风险评估方法。成果可为高寒强震山区国家重大工程风险调控提供科学依据，其中地震涌浪模型具原创性。

近年来随着全球气候变暖和冰川消融,高寒强震山区冰碛湖溃决事件增多。汶川地震表明，地震引发库湖水体涌浪的强度，可能超过冰碛坝溃决的临界水文条件，但目前对堰塞湖溃决风险源的排查中，一直忽视了地震涌浪的危害作用。项目主要研究地震涌浪机理、溢流型堰塞坝溃决机理、地震振动与动水压力综合作用下堰塞坝失稳机理，以及高寒强震区线路系统全寿命服役期冰湖溃决风险调控理论等。堰塞湖多为小型湖泊。研究发现当水体宽度小于100 m、水深低于20 m时，极易发生地震共振涌浪现象，导致涌浪高于非共振时的数倍。鉴此，建立了共振条件下冰碛堰塞湖地震涌浪最大波高计算公式、动水压力计算公式；依据非均匀沙起动临界水头高度与溃坝输沙临界水量条件，提出了堰塞坝漫顶溃决判据；以川藏铁路泊隆藏布流域为例，绘制了冰碛堰塞湖危险性评估图。此外，针对地震时又发生地震滑坡入水的复杂情况，建立了地震与滑坡共同作用引发涌浪模型、地震与水下滑坡碎屑流共同作用引发涌浪模型。最后针对堰塞湖高风险区，提出了减灾选线要点。冰川区是我国没有大型工程建设实践的地貌单元，冰湖溃决也是铁路没有应对过的特殊的灾种。成果可为高寒强震山区拟建干线铁路，如川藏铁路、中巴铁路、中尼铁路等堰塞湖溃决风险调控提供技术支撑，其中共振条件下地震涌浪计算公式与冰碛堰塞坝溃决判据具原创性。.项目共资助发表论文21篇，其中第一资助论文11篇，包含5篇SCI，2篇EI，1篇ESCI，3篇CSCD；第二资助论文10篇，包含3篇SCI，1篇EI，6篇CSCD。获软件著作权2项。培养毕业博士研究生5名、硕士研究生10名；在读博士研究生2名、硕士研究生4名。以项目组提出的堰塞湖灾害链铁路减灾选线技术为支撑材料之一，成果“山区铁路减灾选线理论、方法与技术”获2019年中国交通运输协会科技进步特等奖。项目绘制的“泊隆藏布冰湖溃决危险度分布图”为川藏铁路预可研报告通过评审，提供了科技支撑。