| In the southern part of China,the construction of highways will inevitably be affected by topography and geology.When crossing mountainous and heavy hills,the coarse-grained soil is considered to have good engineering characteristics,so many projects use coarse-grained soil as embankment filler,forming a large number of coarse-grain soil high embankment project.However,under the influence of slope erosion and rainfall infiltration,the instability of coarse-grained soil filler during vehicle operation will cause instability during operation,threatening the safety of highway traffic,and greatly reducing the design life of the embankment.Based on General program of NSFC "Research on service performance evolution and state control technology of coarse-grained high embankment under dynamic humidification(51678073)",which is presided by my tutor Professor Zhong-ming He.And then,combined with indoor slope erosion model tests and numerical simulation methods,In-depth study of the evolution of scour characteristics of high-coarse-grained embankment under different scouring influence factors.Based on the results of laboratory tests,the soil hydraulic characteristics and stability of the coarse-grained soil embankment under rainfall conditions was analyzed using numerical software.The main research conclusions obtained in this article are as follows.(1)Under the effect of rainfall scouring,the scouring evolution process of coarse-grained soil high embankment slope can be roughly divided into four different stages:raindrop erosion,surface erosion,rill erosion,and ditch erosion.Among them,ditch erosion has the greatest impact on slope erosion;Raindrops have a wide range of distribution and are random,while surface erosion is gradually derived after runoff from the slope;rill erosion easily occurs at the terrain with undulations,which plays a role in connecting different erosion areas,then the surface erosion gradually changed to linear erosion.When the rill erosion gradually changed to the trench erosion,the slope as a whole changed from surface erosion to linear erosion.(2)The corresponding numerical model was established by Geo-Studio numerical simulation software,and the curve fitting of soil-water characteristics was carried out by Van-Genuchten model,and the variation rules of pore water pressure and volume water content of embankment slope under the condition of rainfall erosion were analyzed.Then the seepage results of high embankment slope with coarse soil under the condition of rainfall erosion were imported into FLAC3D software through fish language,and the rainfall erosion stability of high embankment slope with coarse soil was calculated.(3)The evolution of the scour characteristics of the embankment slope under different rainfall intensities and slope gradients were studied respectively.According to the test results,it is known that the cumulative erosion on the slope surface of the embankment gradually increases with the increase of rainfall duration.Different rainfall intensity causes the cumulative erosion rate increases as follows:heavy rain>moderate rain>light rain;the cumulative erosion amount increases first and then decreases as the slope gradient increases.There is a critical slope for erosion of the embankment filled with coarse grained soil.The fitting results show that the critical slope of the coarse-grained soil slope is between 40° and 45°.(4)Under three different compaction degrees,the increasing rate of cumulative erosion of embankment slope is:compaction degree 90%>compaction degree 93%>compaction degree 96%;In the early stage,there is little difference in the change rate of the flushing amount on the slope with different compaction degrees.With the development of rainfall,the cumulative erosion amount of the embankment slope with large compaction degree increases at a smaller rate;And compared with the slope with small compaction degree,the erosion rate growth period is relatively lagging. |
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