| Suffering severe soil erosion,the Loess Plateau in China has complex geology and fragile ecology.Long term practice shows that the check dam project reduces the sediment carrying capacity of flood,but also silt up land for farmland and increase grain production,has played an important role in the control of soil erosion in the Loess Plateau and in promoting local economic development.The determination of dam height is an important part in the design link of a check dam.At present,the dam height of check dam is mostly designed according to the specifications.partly based on experience,and lack of further optimization research.Thus,the calculation method of dam height is discussed in order to provide reference for the design of check dam.From the economic point of view,this paper sets up an optimization model for the design height of check dam considering the safety risks while pursuing the maximum benefit of the project.Based on the actual engineering analysis and application,the MATLAB toolbox is used to solve the problem,so as to verify the scientificity and applicability of the model.The main research contents and achievements of this paper include:(1)Based on the theory of objective optimization,the dam height to retard mud and the dam height to retention flood are optimized.Starting from the difference between the economic benefits and the project costs generated by the check dam,and taking the dam height to retard mud and the dam height to retention flood as decision variables,the relationship between the construction benefits,costs and dam height of check dam is clarified and quantitatively analyzed.Considering the constraints of silted-land area,sediment retention,,flood detention,allowable submerged depth and topographic conditions,the objective optimization function of efficiency cost difference—dam height is established.(2)The concept of risk is introduced to determine the value of safe superelevation.On the basis of the optimum dam height to retard mud and the optimum dam height to retention flood,the overtopping risk theory is applied to calculate the overtopping failure probability under different safety superelevation values,considering the flood uncertainty factors caused by heavy rainfall.Refer to the "allowable risk analysis method" prevailing abroad to determine the overtopping risk standard and select the safe superelevation value,so as to establish the optimization model for the design dam height of check dam.(3)The model is applied to the practical project of Huweigou check dam.Calculating and analyzing the relevant parameters of the project example,the optimization model of the design dam height based on the Huweigou check dam project is constructed.By solving the nonlinear constrained optimization problem and applying Monte Carlo method,the optimized total dam height is 19.53 m,among which the optimum dam height to retard mud is 14.66 m and the optimum dam height to detention flood is 3.24 m,and the value of safety superelevation is 1.63 m.The overall result is in line with the actual situation and is relatively ideal.Through the research,it can be found that the model established in this paper has certain applicability and scientificity,and provides a new idea for the study of check Dam design. |
