Wind-blown Sand Load And Wind Erosion Of Bridge Under Air-borne Sand Environment

The research contents of this dissertation is part of the National Nature Foundation General Project(51778051)named "research on wind load and wind erosion mechanism of concrete structures in wind-blown sand environment".The northwest region of China is the forefront of the "Belt and Road" domestic section.The construction of the Northwest Economic Corridor is advancing steadily and the transportation system is being continuously optimized.The direct and indirect economic losses caused by wind-sand weather are serious in northwest China.As an important part of the traffic system,the reasonable calculation of the wind-sand load on the bridge in the wind-sand environment is the key to design the bridge.The safety and durability of bridges are also severely tested by the long-term erosion of wind-blown sand.The complicated flow of wind and sand will cause different degrees of wind erosion.Therefore,it is very urgent and important to study the wind load and wind erosion of bridges in the northwest wind-sand environment.The main contents of this paper are as follows:(1)A flat sand-bed model is established to verify the accuracy of parameter setting when using Euler two-phase flow model to simulate wind-blown sand flow.The numerical simulation results are compared with the previous literature to verify the rationality of the numerical simulation method.(2)Numerical simulation and analysis of bridge regional wind field and bridge regional wind sand flow field under pure wind environment and wind sand environment.The three-dimensional Bridge model is established to analyze the changes of wind-sand flow field in the bridge area,and the changes of bridge surface pressure in pure wind environment and wind-sand environment are compared The numerical simulation wind load and wind sand load are compared with the calculated wind load in the code for wind resistance design of highway bridges.The results show that the wind-sand load is much larger than the wind-sand load,so the effect of wind-sand load should be considered in the area with larger wind-sand load.(3)Numerical simulation of Aeolian sand flow field under different Aeolian sand flow parameters.The variation of the wind-sand pressure on the windward and leeward sides of the bridge and the wind-sand pressure on the specified path under different attack angle of wind-sand,wind-sand Velocity,sand content and particle size are analyzed.(4)The changes of wind pressure on the bridge surface under the condition of 90 and 45 wind sand attack angles are compared.The contrast of the bridge surface(windward side and Leeward side)pressure with the change of wind sand velocity,sand content and particle size is analyzed.(5)The critical wind erosion velocity is determined according to the analysis and study of the existing test data,the critical wind erosion pressure is studied according to the numerical simulation of the test parameters,and the 90 and 45 attack angles of wind erosion are studied according to the critical wind erosion pressure The Rule of wind erosion on the bridge windward surface under different wind velocity,sand content and particle size.Some suggestions are provided for the selection of wind sand attack angle and the prevention of wind erosion in bridge design.