Random Experimental Study On Pebble Movement In Mountain River

For the non-uniform bed load that is common in the transitional section of natural mountain rivers and plain rivers,due to the fluctuation of the river bed flow,the shape of the bed surface,the unevenness of the bed sand composition and the uncertainty of the position of the bed surface and the changes in the recharge conditions on the upstream section Sex,making pebble movement random in time and space.It is necessary to know the movement process of pebbles in time and space,and the status of different movement positions.It is innovative to use advanced tracking technology to obtain the state information during the movement of pebbles.This paper first establishes a calibration experiment indoors,calibrates the credibility of the acceleration sensor to record the movement state,and statistically illustrates its movement characteristics.Through carrying out the water tank model test,the quaternion method is used to solve the pebble movement state information recorded by the acceleration sensor,and finally the pebble movement trajectory is retrieved to establish the spatial image information of the movement state and describe it.In the calibration experiment,three different types of bed surfaces and three different slope experiments were designed.The camera used the camera to record the pebble movement track of the built-in acceleration sensor,combined with the video data recorded by the camera to process the pebble movement track.The number method is used to calculate the motion state information recorded by the acceleration sensor.Finally,the statistical principle is used to analyze the change of the single step distance and single step angle during the movement of the sphere model pebble under this condition.conclusion as below:1.At slopes of 14°,15° and 16°,the movement of the model pebbles on the uneven bed surface is the most unstable.The ratio of the maximum and minimum values of L and the maximum value of ? are concentrated in the three bed shapes The ratio of the value to the minimum value is close to a constant,and the percentage of concentrated jumps in the total number of jumps decreases sequentially;2.With the increase of the slope,the average change of the single step distance of the movements on different bed surfaces respectively follows the quadratic function and the successive function distribution.Based on the feasibility analysis of the tracing and positioning technology of the acceleration sensor based on the calibration experiment,a water tank test was carried out.The test was arranged with the same specifications and built-in the same type of acceleration sensor to monitor the movement status of the model pebbles in the water tank.Using the quaternion method,the position information of the model pebbles in the geographic coordinate system is obtained,and finally the spatial image information of the moving state is established and described.conclusion as below:1.1# and 2# The ratio of the maximum single step distance and the minimum single step distance of pebbles is(+0.25)7.75,and the ratio of the maximum jump angle and the minimum jump angle is(+0.5)22.5;2.The probability density distribution fitting curve of the pebble L/D approximates the gamma distribution,the jumping angle is concentrated around a fixed degree and floats,and is evenly distributed in a specific interval.