A Study Of The Mechanism Of Non-orthogonal Rainfall Infiltration On Surfaces Of Silt Slopes Based On Digital Image Processing

Unsaturated soil slope are the most common in nature and engineering practice.Seepage results from rainfall, leading to slope deformation and instability, which isthe root cause of landslides. Resulting from rainfall, seepage which leads to slopedeformation and instability is also the root cause of landslides. Given this, it is of vitalimportance to study water infiltration mechanism at the condition of rainfall. Whereasin existing theory, it is common to do the flow orthogonal decomposition inaccordance with the slope angle and regard it as second boundary condition inseepage analysis when dealing with rainfall infiltration. This theory is calledorthogonal theory. However, it is observably different from reality.The silt soil-water characteristic curve (SWCC) was obtained and the unsaturatedhydraulic conductivity under various matrix suction was derived through SWCCpressure meter. It can be seen from the results: the smaller the matrix suction, thegreater the soil void ratio, and the greater the permeability coefficient. But when thematrix suction reaches a certain value, the greater the soil void ratio, while the smallerthe permeability coefficient.The paper researched the effects of rainfall intensity, soil compactness and slopeangle on infiltration mode through unsaturated silt laboratory rainfall model test. Thetests shows that:(1) with the increase of rainfall intensity, the seepage of the test cellslope surface, the seepage of the bottom and the seepage of the side are increased withfaster production rate;(2) the larger the soil void ratio, the smaller the seepage of thetest cell slope, the larger the seepage of the bottom and the side;(3)when the rainfallintensity is constant, the greater the slope, the smaller the seepage of the slope, thebottom and the side.The second part of the work was taking use of the SEEP/W module of GeoStudiofor numerical simulation about unsaturated silt laboratory model test. Comparing thenumerical results and the experimental results, we can see: traditional orthogonaltheory adopted in numerical calculation leads to the great difference between therunoff via numerical calculation and the runoff via experiment. In the initial of rainfall,the runoff via numerical calculation is greater than the runoff via experiment, in thelatter, the result is on the contrary, which leads to the surface infiltration via numerical calculation is too large and the seepage of the bottom and the side is greater than thetest results. The effects of rainfall intensity, soil compactness and slope angle oninfiltration in numerical calculation is consistent with the test ones.Finally, picture of infiltration of soil profile were gained by means of digitalpicture processing technique. The development of moist peak was studied underdifferent levels of rainfall intensity, void ratio and slope angle, from which we candraw the conclusion that the advance speed increases with the increase of rainfallintensity and void ratio; when the rainfall intensity is constant, the greater the slopeangle, the slower moist peak front advance...