| The ecological permeable dam not only has the function of water retaining,but also ensures the downstream ecological water supply and purifies the water quality.Eco-permeable dam technology,using dam stability and seepage function,combined with rapid seepage mechanism and artificial wetland purification method,forms a complex combined and efficient operation mode.Permeable dams have the function of "retaining water" and "permeating and filtering water".By controlling the seepage flow of the permeable dam,the upstream water level of the dam and the permeability of the dam body can be raised.When the polluted water seeps through the dam,the permeable dam purifies the water quality by using the principles of plant absorption and microbial decomposition on the dam body while passing through the physical filtration of the dam body.Ecological permeable dams play an important role in ecological control and water pollution control at the present stage in China.Due to the permeability of the dam body,the permeability coefficient of the dam material is much larger than that of the earth-rock dam.At present,there is no relevant code for the design of the structure of the dam body.On the basis of summarizing the previous studies on permeable dams,the main contents and achievements of this paper are as follows:(1)Aiming at the non-point source pollution problem of Yanghe Reservoir,an ecological permeable dam project will be designed and constructed at the entrance of the main stream of Dongyang River in the upper reaches of Yanghe Reservoir.The pre-reservoir formed by the permeable dam and the ecological wetland behind the dam will be used to treat the sewage and reduce the pollutant content in the Yanghe Reservoir.Determine the design purpose,design content and design steps of ecological permeable dam.It includes the selection principle of dam filter material,plant selection principle and site selection principle.(2)On the basis of summarizing the structure design of permeable dam by predecessors,according to the principle of water purification of permeable dam and making full use of channel space,a new type of permeable dam with composite structure is designed.To a certain extent,the problem of unstable dam body,uncontrollable seepage volume,dam silting and flood crossing in the development of permeable dam technology has been solved and studied.According to the engineering data,the size of the permeable dam,the filter material of the dam body and the plants on the dam are designed.(3)The seepage and stability of composite structure permeable dam are calculated and analyzed to verify its rationality,reliability and stability.Seepage flow and dam slope stability are calculated and analyzed by Seep/w and Slope/w modules in Geo-studio finite element software.The results meet the requirements.The overall structural stability of the permeable dam is calculated by ANSYS finite element software.The results show that the deformation and stress of the permeable dam body can meet the basic requirements of strength and stability.(4)Scale the design prototype of the ecological permeable dam according to the geometric and dynamic similarities,build the physical model and carry out experiments,verify the accuracy of the calculation results by measuring the seepage of the dam model,verify the removal effect of pollutants in sewage by measuring the SS concentration of sewage,and explore the permeability by continuously measuring the permeability of the model.The law of change with time predicts the time of replacement of the ecological cushion and the filter material of the permeable dam. |
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