Experimental Study On The Erosion Characteristics Of The Pipeline Crossing The Sedimentary River

The pipes buried at the bottom of the river channel are in a very harsh environment.The riverbed near the pipeline is very prone to drowsiness due to the hydrodynamic forces such as waves and tides,which finally leads to the river bottom pipeline under the influence of hydrodynamic forces and third-party activities.Damage occurs from time to time,so it is very important to study the characteristics of the pipeline around the silt channel.The test mainly in the shallow laying state,(1)Based on the physical model test of plexiglass tank,the erosive characteristics of the river bottom pipe in the shallow buried state;(2)A series of physical changes to the river bed scour near a pipeline are described by means of simultaneous measurements of the ADV instrument and video observations;(3)The depth of the scouring pit and the evolution of the channel were measured after the bottom scouring equilibrium was stabilized;(4)The three-dimensional hydraulic characteristics of the pipe around the test data measured turbulence,Reynolds stress and flow field analysis of three aspects of the general law of the riverbed erosion.Contrast under different conditions of pipeline erosion,the test results show that:(1)Pipeline scouring will reach equilibrium after a period of time and will not be washed down continuously.In this experiment,the flow of 27.03L/s will drop 2cm after 10 minutes,and the pipe will be exposed after scouring for 31 minutes Sand all away,scouring 57 minutes in front of the tube began to appear at 1.3cm scour pit appears pit position is about 1/2 of the diameter of the final scour pit up to 4cm deep tend to no longer continue to develop;30.00L/s after 6minutes to carry water flow away 2cm model sand,scouring for 17 minutes the pipe exposed,scour 22 minutes began to flush pit was washed away,the scour pit appeared in the tube1.2cm at the location of the pit is the test The pipe 1/2,the final scouring pit up to 5.5cm eventually tends to be stable,water erosion on the pipeline will not continue continuously;(2)In terms of flow rate,the vertical flow velocity,vertical flow velocity,and planar mean flow velocity under the three states of no-blow-up,lift-up,and flush-exposed-to-stabilize flow,and the flow velocity increases with the distance from the water surface in the middle of the flow.Linearly increasing;(3)In terms of turbulence intensity and Reynolds stress,the distance between the water surface height and turbulence intensity is linearly increasing in the middle layer of the water body's liquid surface,which is consistent with the change law of the flow velocity;(4)According to the pipeline In the analysis of flushing and flushing exposed to a steady state,the pipeline is affected by the flow field in the range of 1.5 to 2.5 times the pipe diameter.In this range,it is necessary to protect the pipeline.