含沙溃堤洪水数值模拟分析

发布时间：2018-06-27 01:52

本文选题：含沙洪水 + 溃堤　；参考：《天津大学》2016年硕士论文

【摘要】：分析溃堤洪水风险可以为防洪决策提供依据,对于泥沙含量较高的河流而言,溃堤洪水为含沙水流,含沙溃堤洪水在造成洪水淹没的同时伴随着泥沙冲淤。大量的泥沙淤积会加重洪水的溃堤风险和财产损失。同时,溃堤洪水造成的床面冲淤变化会影响洪水演进和进洪过程,因此评估多沙河流堤防溃决时水沙联合作用引起的灾情对控制溃堤风险具有实际意义。本文在前人研究的基础上,针对洪泛区的实际情况,建立适合于多沙河道的溃堤洪水数学模型,并将模型应用于黄河某溃口的溃堤洪水计算,分析含沙溃堤洪水的水沙运动规律,研究床面泥沙冲淤对溃堤出流和洪水演进速度的影响,评估水沙联合作用下的风险。主要研究内容如下:(1)采用非结构化三角网格建模,建立一个适合于多沙河道与复杂洪泛区的二维溃堤洪水水沙数学模型。模型考虑床面冲淤变化对水沙运动的影响,对洪泛区的道路、村庄等建筑物进行概化处理,通过适时改变溃口的长度和高度来模拟溃口横向展宽和纵向冲刷的发展过程。模型单元界面的水动力通量采用基于近似黎曼解的Roe格式计算,泥沙通量采用TVD-MUSCL格式求解。(2)分别采用定床溃坝试验数据和动床溃坝试验数据对模型进行验证,将模型数据与试验数据进行对比分析发现,模型既能较好地模拟定床条件下的堤坝溃决水流运动,又能较好地模拟动床条件下的堤坝溃决的水沙运动和床面冲於变化。(3)将模型应用于黄河某险工段100年一遇含沙水流溃堤模拟,对模型的水位、流速、含沙量、床面冲於等计算结果进行分析。总结含沙溃堤水流的水沙运动和泥沙冲淤规律。(4)为了分析泥沙冲淤对溃堤出流和洪水演进过程的影响,将应用实例分“清水定床”、“清水动床”、“含沙洪水定床”和“含沙洪水动床”四种模型进计算,并对四种模型的溃堤出流计算结果进行比较,分析泥沙冲淤对溃堤出流和洪水演进过程影响的原因,评估水沙联合作用下的风险。研究结果表明,多沙河道溃堤洪水的含沙量沿程减小,淹没范围内会形成较大范围的泥沙淤积,泥沙淤积体主要集中在溃口冲刷坑外围附近,泥沙淤积体呈环形分布。溃口附近的泥沙冲淤会影响溃堤洪水的溃堤出流量和洪水演进过程,冲刷坑的形成会增大溃堤出流量和淹没范围,淤积体的形成会减小溃堤出流量和淹没范围。研究结果对多沙河道防洪防沙决策具有一定的指导价值。
[Abstract]:Analyzing the flood risk of embankment break can provide the basis for flood control decision. For rivers with high sediment content, embankment break flood is a sediment bearing flow, and sediment erosion and siltation are accompanied by the flood caused by sediment break flood at the same time. A large amount of silt will increase the risk of flood breakwater and property loss. At the same time, the change of bed surface scour and silt caused by embankment break flood will affect the flood routing and flood inflow process. Therefore, it is of practical significance to evaluate the disaster situation caused by the combined action of water and sediment in the course of embankment collapse in many sand rivers in order to control the risk of embankment break. On the basis of previous studies and in view of the actual situation in the floodplain, this paper establishes a mathematical model of embankment break flood suitable for the Dosha River channel, and applies the model to the calculation of the breakwater flood at a certain breakage of the Yellow River. This paper analyzes the rule of water and sediment movement of flood with sediment break, studies the influence of sediment scouring and silting on the velocity of flood flow and flood routing, and assesses the risk under the combined action of water and sand. The main contents are as follows: (1) an unstructured triangular mesh model is used to establish a two-dimensional mathematical model of flood water and sediment for multi-sand channel and complex floodplain. Considering the influence of bed erosion and siltation on the movement of water and sediment, the model generalizes the buildings in floodplain area, such as roads and villages, and simulates the development process of transverse widening and longitudinal erosion of the burst by changing the length and height of the burst at the right time. The hydrodynamic flux at the interface of the model is calculated by Roe scheme based on approximate Riemannian solution, and sediment flux is solved by TVD-MUSCL scheme. (2) the model is verified by the fixed bed dam-break test data and the moving-bed dam-break test data, respectively. By comparing the model data with the experimental data, it is found that the model can not only simulate the movement of burst flow under fixed bed condition, It can also be used to simulate the movement of water and sediment and the change of bed surface flushing under the condition of moving bed. (3) the model is applied to a dangerous section of the Yellow River once in 100 years to simulate the water level, velocity and sediment content of the model. The results of calculation are analyzed. In order to analyze the influence of sediment erosion and siltation on the discharge and flood evolution process of break embankment, the application examples are divided into "clear water fixed bed" and "clear water moving bed". Four models of "sediment bearing flood fixed bed" and "sediment flood moving bed" were calculated, and the results of the four models were compared, and the reasons for the influence of sediment scouring and silting on the breakwater discharge and flood routing process were analyzed. Assess the risk of a combination of water and sand. The results show that the sediment content of the embankment burst flood of the Duosha River Road decreases along the course, and a large area of sediment siltation will be formed in the submerged area. The sediment silt is mainly concentrated near the scour pit of the crater, and the sediment silt is distributed in a circular way. The sediment scouring and silting near the breakwater will affect the discharge and the course of flood routing, the formation of scour pit will increase the discharge and inundation range, and the formation of silt will reduce the discharge and submergence range. The research results have certain guiding value for the decision of flood control and sand control of the Duosha River channel.
【学位授予单位】：天津大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TV122.4

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