Study On The Mechanical Mechanism Of Splash Erosion Of Loose Pisha-sandstone

Splash erosion is the mechanical process of raindrops working on the surface soil layer,and it is the main soil erosion method in the early stage of rainfall.The splashing action of raindrops destroys the surface soil structure and causes the topsoil to be discrete or directly cause the particles to move.This process causes the surface soil pores to clog and the infiltration capacity to decrease.The splashing effect also increases the turbulence intensity of the surface runoff,thereby enhancing the sediment transport capacity of the rainfall runoff and directly affecting the hydraulic erosion process of the soil.The sandstone structure is loose,the water erosion is serious,and the soil is sand.The self-bonding force is poor,and it is difficult to form agglomerates.Therefore,it is of great significance to study the erosion of the sandstone.In this paper,the Ordos loose sandstone was used as the research object.The simulated artificial rainfall and self-made splash collection device were used to conduct the sandstone splash erosion test.The rainfall intensity,slope and splash collection orientation were studied for the amount of soil erosion and the effect of particle size composition.Through the in-depth study of the spattering quality of the up and down slope and the change of the grain size of the sputtered grain,the mechanism of the spattering on the slope of the bony sandstone is revealed.Research indicates:1.The amount of erosion on the upper and lower slopes increases exponentially with the increase of kinetic energy of rainfall,but the increase of the amount of upslope erosion is much smaller than that of downhill.2.The amount of erosion on the uphill slope decreases linearly with the increase of slope;the amount of erosion on the downhill slope increases first and then decreases with the increase of slope,and the critical slope of downhill erosion occurs near 25°.The variation of the kinetic energy of rainfall along the downhill and slope surface with the slope is an important cause of the critical slope.3.Based on the sputter mechanics model,a two-factor splashing erosion model of the erosive energy and slope of the sandstone is established.The model can better reflect the variation of the erosion amount of the upper and lower slopes with the rain intensity and slope.4.Soil erosion is the result of the coupling of various factors such as rainfall conditions,slope structure and soil mechanical composition.When the slope is below 20°,the rain intensity is the main influencing factor of the rain erosion particle size sorting;when the slope reaches 30° and above,the slope and rain intensity become the main influencing factors of rainfall splashing particle size sorting;When the rainfall intensity and slope are the same,the segregation is the most obvious for the separation of fine sand,followed by medium sand,very fine sand and silt.the original Pisha-sandstone,the particle size distribution of the spoiled soil sample is coarser.When the rain intensity is less than 80mm/h,the rainfall condition is the main factor affecting the particle size composition of the spoiled soil sample.When the rain is stronger than 80mm/h,the slope factor has an obvious influence on the particle size composition of the spoiled soil sample.