猴子岩水库色玉滑坡涌浪灾害链CFD–DEM耦合数值模拟

CFD–DEM Coupling Numerical Simulation of the Seyu Landslide–Surge Disaster Chain in Houziyan Reservoir

滑坡涌浪是一种常见的地质灾害现象,由于滑坡体与水体之间存在复杂的流固耦合作用,使得传统的单一介质模型无法进行准确求解。为此,介绍一种基于计算流体力学方法(CFD)与离散单元法(DEM)的流固耦合模型CFD–DEM,采用计算流体力学方法(CFD)求解水体流动,采用离散单元法(DEM)模拟散粒体滑坡运动,充分利用不同计算模型的优势,对滑坡及涌浪演进过程进行数值模拟分析。首先,利用该耦合模型对Robbe–Saule开展的颗粒堆积体坍塌–涌浪试验进行了相同工况下的数值计算,从颗粒坍塌运动过程、涌浪高度演化过程等方面进行对比,结果表明模拟结果与试验结果吻合很好,验证了CFD–DEM流固耦合模型的有效性。然后,将该方法应用于四川省猴子岩水库色玉滑坡–涌浪灾害的演进过程分析,重现了该事件滑坡失稳运动、涌浪产生及传播、涌浪爬升、涌浪回流的全过程,计算结果显示:计算得到的电站进水口处涌浪高度与实测数据较为接近;色玉滑坡从失稳运动至静止堆积的持续时间约为20 s,颗粒平均速度最大达到16.12 m/s;滑坡引起的涌浪约在滑坡失稳10 s后传播到对岸,之后开始沿坡面向上爬升,最大爬升高度达到27.32 m。研究表明CFD–DEM流固耦合模型能够很好地应用于模拟山区河谷大规模滑坡涌浪灾害,可为库区防灾减灾提供高效的技术支持。

Landslide surge is a common geological disaster phenomenon. Due to the complex fluid-solid interaction between landslides and water,the traditional single-medium model cannot be solved accurately. Therefore, based on a coupling model of computational fluid dynamics(CFD)and discrete element method(DEM), the CFD method was used to simulate the water flow, and the DEM was used to simulate the motion of a granular landslide. Taking full advantage of the advantages of different computational models, the evolution process of landslide and surge was numerically simulated and analyzed. Firstly, this method was used to numerically simulate the particle accumulation collapse-surge experiment carried out by Robbe-Saule under the same working conditions. The particle motion process and the surge propagation process showed that the simulation results were in good agreement with the experimental results, which verified the effectiveness of the CFD–DEM fluid-solid coupling model. Then, the method was applied to analyze the evolution process of Seyu landslide-surge disaster in Houziyan reservoir of Sichuan Province,and the whole process of landslide movement, surge generation and propagation, surge climbing on the opposite bank and surge backflow was reproduced. The calculated surge height at the inlet of the power station was close to the measured data. The calculation results showed that the duration from unstable movement to static accumulation of Seyu landslide was about 20 s, and the maximum average particle velocity reached 16.12m/s. The surge caused by the landslide spread to the opposite bank after about 10 s and then began to climb along the slope, with the maximum climbing height reaching 27.32 m. The research showed that the CFD–DEM fluid-solid coupling model could be well applied to the simulation of large-scale landslide and surge disasters in mountainous valleys, which could provide efficient technical support for disaster prevention and mitigation in the reservoir area.