Experimental And Simulation Study On Scour Depth Of Roadbed Along River Highway

During highway construction,sometimes parallel to the river channel occurs,and one side of the river channel becomes the roadbed.At this time,the water flow in the river channel will inevitably scrub the roadbed of the road.Harm to the safety of people’s lives and property.Therefore,in order to avoid such accidents,it is necessary to explore the maximum erosion depth of the roadbed along the river.This thesis combines physical model tests and numerical simulation methods to analyze various factors that affect the erosion depth of the roadbed along the river.The following conclusions can be obtained through analysis:(1)With the increase of discharge in the straight section of the river,the water depth increases exponentially,the flow velocity increases logarithmically,and the channel scour depth increases linearly.Under the same conditions,the water depth of the middle river bed is light model sand,the water depth is larger,the flow velocity is smaller,and the scouring depth is larger.When the bed quality is natural sand,the water depth is small,the flow velocity is large,and the scouring depth is small.Through quantitative analysis of various factors affecting the erosion depth of the roadbed along the river,the combination of experimental data established a parallel bank erosion depth formula.(2)The water depth of the concave side increases continuously after entering the bend,and decreases continuously after exiting the bend,reaching the maximum near the exit of the bend.The water depth on the convex side of the curve decreases continuously,increases after flowing out of the curve,and reaches a minimum near the exit of the curve.The maximum point of the water depth of the concave side and the minimum point of the water depth of the convex side continue to move from the vicinity of the downstream of the bend to the upstream,that is,the outlet of the bend,with the increase of the flow rate and the bend angle.The water depth and water level on the concave side are greater than those on the convex side.The water depth difference between the two sides reaches the maximum near the exit of the bend,and the water drop on both sides reaches the maximum at the top of the bend.After the water flow enters the bend,the flow velocity starts to be unevenly distributed.The convexside flow velocity at the crest is greater than the concave side flow velocity,and the rear concave side flow velocity continues to increase and the convex side flow velocity is suppressed.The increase of the bend angle has a significant inhibitory effect on the flow velocity of the flow.At the same flow rate,the flow velocity of the flow decreases with the increase of the bend angle.Under the same conditions,the water depth of each section when the riverbed quality is model sand is greater than that when the riverbed quality is natural sand,and the flow velocity is less than when the riverbed quality is natural sand.(3)Due to the existence of the bend,a spiral flow clockwise in the direction of the flow appears on the concave side of the river bend.As a result,the sediment in the bend is transported laterally,and the sediment on the concave side is washed away by the sediment on the convex side.The scouring depth of the concave side of the bend increases with the increase of flow rate and bend angle.The scouring area continues from near the top of the bend to the downstream straight section,and the scouring depth reaches the maximum near the exit of the bend.The position of the maximum erosion depth continuously moves toward the exit of the curve as the bend angle increases.Under the same conditions,the erosion depth when the riverbed quality is natural sand is significantly less than the erosion depth of the riverbed quality model sand.Flow factors,geometric boundaries,and river bed quality factors affect each other and work together on the scouring depth of river bends.Based on the theoretical analysis,combined with the calculation formula for the erosion depth of the parallel revetment and the multiple sets of test data in this paper,a calculation formula suitable for the erosion depth of the channel sediment is fitted.(4)A three-dimensional numerical model of roadbed erosion along the river was established,and flow-3d was used to solve it.The numerical simulation shows that the characteristics of the flow and the coincidence of the measured values of the channel erosion and the simulated values are high.Confirmed the accuracy and usability of numerical simulation.Provide theoretical support for the calculation of roadbed erosion along the river.