Experimental Study On The Force Of Block Under Water Flow

The study on the loss of the dangerous dike of the Yellow River has always been a problem closely related to the actual production,Years of practice has proved that the dam bank collapse,insects and other dangerous situation,more than 60%is caused by the loss of the dam bank root stone.Aiming at the existing research basis,this paper,from the perspective of mechanics,generalizes the shape of the root rock body into cubes of length(L),width(b)and height(s)by means of model test,Considering the effects of Reynolds number,block inclination and block shape parameters on the drag coefficient,Research findings:When Re_s>1.80×10~4,the horizontal drag coefficient increases linearly with the Reynolds number increase,When Re_s<1.80×10~4,the horizontal drag coefficient tends to be stable,and its value is between 0.76 and 0.82.When the angle of the block is less than 6°,the horizontal drag coefficient increases slowly with the increase of the angle of the block,when the angle is greater than 6°,the horizontal drag coefficient decreases with the increase of the angle between the blocks.The drag coefficient varies from 0.81 to 0.88.The shape parameters of the block are usually characterized by aspect ratio(b/s)and aspect ratio(L/s),which change the size and shape parameters of the block.The horizontal drag coefficient of the block varies with the aspect ratio(b/s),the ratio of length to height(L/s)increases,and eventually it will tend to be stable.The change of drag coefficient is obviously affected by the shape parameters of the block,and its value is between0.74 and 0.87.In order to study the influence of water flow velocity on the process of root-rock scouring in actual engineering,The normal physical model test of water flow erosion in the dam body of the gao shan temple project was carried out.Under three different flow conditions,the results are as follows:(1)The flow velocity before the dam is roughly distributed between the observation sections CS3~CS6,from 1.2m to 2.8m from the starting point of the right bank,and the maximum flow velocity is about 2.0 m.(2)a cube with a side length of 2.2 cm was placed at the cross-angle of the dam body of the model,and the drag force of the underwater block was tested.The results showed that the flow velocity was between 33.0 cm/s~48.0 cm/s,the drag force coefficient ranged from 0.73 to 0.93,and the average value was 0.84.(3)the root rock material of the dam body collapses,and the slope deformation declines,and the deformation mainly occurs between 1 and 4 of the slope,especially at the position where section 4 is located.At the flow rate of 60 L/s,the maximum missing area of the root rock material of the dam body is 81 cm~2.