| The tidal bore is a kind of strong nonlinear discontinuous flow with huge energy.The tidal bore has a strong impact on the pier and the scouring action along the river channel,which brings serious safety hazards to the safe operation of the building.At present,there are few studies on the internal hydraulic characteristics of the tidal bore and the mechanism of water and sand movement in the bridge piers.The existing tidal small-scale numerical simulation method has obvious defects in the generation method of tidal bore.Aiming at the above problems,this paper proposes a new numerical simulation method of small-scale fine-scale tidal bore,and combines the physical model test method to analyze the evolution characteristics of water flow structure and the distribution of impact pressure during the process of tidal bore flow.The timehistory response of the pier under the tidal action and its calculation method and the local erosion and deposition characteristics of the pier are discussed.The main research contents are as follows:(1)Based on the method of generating waves by the boundary,a small-scale refinement model of the tidal bore is established and verified by accuracy,which realizes the controllability and convenience of the tidal bore,and overcomes the randomness and applicability of the tidal bore in the predecessor model.(2)Firstly,the hydraulic characteristics of different tidal currents are compared by numerical simulation and the influence of different tidal parameters on the distribution characteristics of tidal currents is analyzed.Then,the flow characteristics at different relative positions of the piers under the tidal action are analyzed.Finally,the hydrodynamic characteristics of the three types of piers under the tidal bore are compared.(3)Through the physical model test,the pressure distribution characteristics of the upstream surface of the pier during the interaction between the tidal current and the pier are discussed.The numerical simulation technology is used to analyze the force generated by the tidal current on the pier,and the domestic and foreign scholars are analyzed in detail.Based on the inapplicability of the discontinuous flow force calculation method to the calculation of the tidal force,a formula for calculating the tidal force with clear physical meaning is proposed.(4)Through the physical model test,the local scouring and silting characteristics of the pier under the tidal action are studied.Firstly,the variation characteristics of the local scouring and silting form of the pier under different influencing parameters are compared,and then the scouring and silting characteristics of the pier and the composite pier are arranged in tandem.The analysis is carried out.Finally,the local scouring mechanism of the pier caused by the tidal current is explored and a calculation formula of the local maximum scouring depth of the pier considering the multi-factor influence is fitted based on the physical test results. |
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