| With the construction and improvement of the Three Gorges Project,the navigation conditions have been greatly improved,and the number of vessels sailing in the narrow river area in the reservoir area has been increasing.Since the impoundment of the Three Gorges Reservoir area,there have been many surge disasters caused by rockfall and landslide under the influence of the fluctuation of water level.However,the landslide in the reservoir area will not only cause casualties and economic losses on the landslide body,but also bring about swell which will threaten the existing construction facilities and goods in the river,such as the wharf,the ships berthed and so on.At present,there are many researches on wave attenuation in wide water area,but the research on landslide surge protection or attenuation in narrow inland river area is relatively weak.In this paper,based on the analysis of the energy dissipation principle of wave-dissipating structures in wide water area,the characteristics of wave dissipating structures in Inland River Basin are summarized.On the basis of comprehensively considering the landslide surge reduction mode in the narrow channel area of the reservoir area and following similar guidelines,three simple physical models of plate,porous and palisade type wave dissipating structures are designed.In the two-dimensional flume experiment,through the comparison experiment of the wave dissipating effects of three simple structures,the palisade type wave dissipating structure is determined as the research object of further experiment.Secondly,through the experiment,the relationship between the efficiency and the influencing factors of the palisade type wave dissipating structure is analyzed,in this paper,the calculation formula of the optimum structure parameters of the palisade type wave dissipating structure is derived and the wave dissipating efficiency of optimal structures in series in three-dimensional environment is discussed.Finally,taking the potential potential surge hazard point of Longmenzhai dangerous rock mass in the Three Gorges Reservoir area as an example,the surge mitigation design is carried out,and the prevention measures and suggestions of surge hazard are given.After the above research,the paper comes to the following conclusions:(1)By carrying out comparative experiments on the wave dissipating effects of three simple structures of 7 groups of plate,palisade,and porous structures,and based on the results of data analysis,it is determined that the palisade type wave dissipating structure is the simple structure with the best wave dissipating efficiency.Based on the principle of controlling a single variable,41 sets of optimization experiments of palisade type wave dissipating structures are designed.The results show that:the total length of the wave breaker and the depth of the water are the main factors that affect the efficiency of the palisade type wave dissipating structure;when the ratio of the total length of the wave breaker to the water depth(L/h_w)is between 0.65and 0.75,the wave dissipation efficiency of the palisade type wave dissipation structure is the best(??0.15);in a three-dimensional environment,palisade type wave dissipation in series the structural parameters of the structure need to meet the requirements of the optimal type design formula for the depth direction of the water and the width direction of the river surface at the same time,in order to exert the best wave dissipation efficiency(?0.21).(2)Based on the field investigation data,the engineering geological conditions of the dangerous rock mass and the threatened objects of the surge disaster in Longmenzhai are analyzed.The results show that the Longmenzhai dangerous rock body is located on the Right Bank of the lower reaches of the Daning River in Wushan,the distance from Longmenzhai dangerous rock body to the mouth of Longmenxia is about 660m and less than 1km to the county town.The distance between the dangerous rock mass and Hongyanzi landslide is about2.9 km,and the distance between the dangerous rock mass and Gongjiafang landslide is about5.0 km.Under the influence of long-term fluctuation of water level,the base rock of Longmenzhai dangerous rock mass appears the corrosion broken zone.If the damage to the base rock mass becomes more and more intense,the base will be completely crushed,resulting in the collapse failure of dangerous rock mass,the surge caused by the collapse will seriously threaten the safety of the vessels and wharves in the area.(3)Taking the 145m water level working condition of the Three Gorges Reservoir area to protect the wharf of the scenic spot as an example,the parameter design of the fence wave dissipating structure and the layout of the wave dissipating zone in the surge control measures to protect the wharf of the scenic spot are analyzed in detail,and the adoption of surge control is compared and analyzed.After the measures and before taking any measures,the economic losses of each terminal in Wushan and the surge value of each terminal.The results show that:arranging 8 square arrays of 4 rows of palisade type wave dissipating structures in the waters along the way where swells propagate can make the swell value of the scenic pier less than2.0m,and the swell value of other piers will also be smaller;and compared with the absence of surge control measures,the use of surge reduction measures can reduce the economic loss of1.554 million yuan as well as the loss of casualties. |
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