Experimental Study On The Internal Erosion Mechanism And Influencing Factors Of Clay-free Soil

Internal soil erosion refers to the phenomenon that the fine particles located in the coarse grain gaps of the skeleton migrate under the action of seepage,which leads to changes in the internal structure and hydraulic characteristics of the soil.It is the main cause of damage to the sandy gravel soil foundation and embankment.In order to study the internal erosion mechanism and its influencing factors of non-clay soil under seepage action,this paper conducted indoor model tests for discontinuously graded sand and gravel using flexible wall seepage devices.The main research contents as follows:(1)Based on the characteristics of the flexible wall seepage device used in this test,a test was carried out for the selected discontinuous gradation of sand and continuously adjusting the range of coarse and fine particles,the partical gradation form that is most prone to erosion phenomena was obtained,and then the factors of the test was gradually changed.Then,have obtained different degrees of erosion response,which are defined as suffusion,suffusion,piping.(2)Analyze representative seepage test groups,respectively explain the phenomena of suffusion,suffusion,piping,summarize the formal test group,and quantify the three types of phenomena through characteristic parameter indicators such as water ouput change,volume shrinkage,vertical displacement,etc.Distinguish,think that volume shrinkage and vertical displacement are important indicators to distinguish the three types of erosion phenomena.(3)The flexible wall seepage device was used to carry out seepage erosion tests under the influence of different fine particle content,surrounding pressure,and various levels of seepage time,Based on the test results,the water output,fine particle loss,the change volume,,the vertical displacement in the process of seepage erosion were analyzed through a single variable method.(4)By comparing and analyzing the gradation changes before and after the erosion of each layer of the sample and the deformation of the sample under different amounts of fine particle loss,the law of seepage and erosion of the soil is analyzed from the perspective of changes in the internal structure of the soil.The samples were subjected to triaxial drainage shear before and after seepage erosion,revealing the effect of seepage erosion on the mechanical properties of non-clay soil.