| With the vigorous development of inland shipping traffic,the trend of large-scale and highspeed ships makes the ship-induced hydrodynamics in the canal increasingly enhanced.The ship waves and corresponding flow changes caused by frequent ships have changed the original hydrodynamic conditions in the channel,and become the most important dynamic factor in the canal section evolution.However,the existing river section morphology theory and evolution simulation do not consider the role of ship-induced hydrodynamics,which can not be fully applied to the canal.Therefore,it is of great scientific significance and application value to introduce ship waves into the study of sediment transport and section shape evolution of canal.Based on the hydrodynamic conditions caused by ships in the canal,this paper explores and studies the key problems of sediment tansport and section shape evolution under the action of ship waves.In this paper,filed observation test,flume test and numerical simulation are combined to explore the influence of ship waves on the cross-section evolution in the canal.The main contents and conclusions of the study are as follows:(1)In view of the hydrodynamic effect caused by frequent ships in the canal,the characterstics of ship waves in the canal under different conditions are studied in time and frequency scales.In the time domain,the structural characteristics of ship wave train are analyzed,and the primary and secondary wave characteristics are defined in the canal.This paper improves the calculation formula of the ship wave height generated by the navigation administration boat and the cargo ship in the canal.In frequency domain,based on the continuous wavelet transform theory,the spectrum characteristics of ship waves and the influence of different factors on the wavelet energy spectrum of shipwaves are analyzed,and the energy distribution characteristics of primary wave and secondary wave are clarified.The results show that the ship wave energy is concentrated in the frequency range of 0～0.35 hz,and the ship wave energy distribution corresponds to the significant degree of the primary wave and the secondary wave.(2)Through theoretical analysis and field observation data,the sediment transport law under the action of ship waves in the canal is revealed.Based on the dynamic mechanism of sediment transport under the action of ship waves,the flow velocity and the shear stress at the bottom are calculated,and the critical condition of sediment incipient motion on the bed surface is obtained.Based on the theory of sediment transport under unidirectional flow and waves,a formula for calculating the sediment carrying capacity of ship waves is established by calculating the modified Sheilds parameters and the corresponding average suspended sediment content.Taking a single cargo ship as an example,the relationship between the maximum value of suspended sediment concentration and the main wave height parameters of ship waves at different positions is established,and the variation characteristics of suspended sediment concentration caused by ships in the canal is analyzed.(3)By means of flume test and numerical simulation,the shape evolution law of canal section under ship waves is revealed.It is found that there is a power exponent relationship between the polygonal area and the perimeter of the trapezoidal cross-section corresponding to the ship waves,which indicates that the shape of the trapezoidal cross-section after adjustment is similar under the action of ship waves.The relationship between the velocity and the maximum scour depth under the action of ship waves is established.Furthermore,the response law of the canal section shape to the navigation conditions of a single ship and two ships is discussed.The relationship between the speed,draft,offshore distance and the depth of erosion and deposition of the trapezoidal cross-section riverbed is established,respectively.The characteristics of riverbed erosion and deposition caused by continuous and opposite navigation of two ships are analyzed,and the influence of ship waves on the evolution of canal section is revealed. |
