Study On Compaction Characteristics Of Large-diameter And Non-cohesive Soil-rock Mixed Subgrade

With the rapid development of infrastructure construction in China,the soil-rock mixture filler is inevitably used in many roadbed filling projects.And for the large-grained soil-stone mixed embankment project,the filling classification method,filling compaction quality control standard,strength and deformation calculation theory,etc.,have not yet formed the theory of system,and have not seen the special design and construction guidance standard,the existing research is based on homogeneous soil or stone-filled roadbed research methods.In view of this,this paper relies on the filling construction of soil-rock mixed high embankment,in view of the characteristics of the embankment filled with different weathering degree of large-grained soft block stone and gravel-soil mixture.The compaction quality of the field was measured by using the E_vdd index and the VCV index,and the particle flow discrete element simulation method was used to study the compaction characteristics of the large particle size non viscous filler.The following major findings have been achieved:（1）According to the test theory and field test,it is pointed out that for the compaction quality test of the mixed filler with large particle size soft rock and soil,the E_vdd index reflects the compactness of the shallow layer of subgrade filling layer or the strength of rock mass,and the VCV index can reflect the structure resistance of subgrade filling layer,so the E_vdd index is more discrete than VCV index.And the higher the rock strength,the greater the degree of dispersion;when the rubble of the filling blocks is broken,the surface compactness of subgrade filling layer is reduced,and because of the large crushing of soft rock,the deformation of the structure is greatly increased,and the resistance of the filling layer is significantly improved.;Under the action of vibratory compaction,the compaction process of the large-grained soft block-rock without viscous filler is mainly manifested in three kinds of processes,such as fragmentation of rock,gravel filling void and gravel rearrangement;there is no correlation between the two test indices in the same filling layer,but under different compaction degree,when the low strength rock is used,The correlations between the two indexes are good,and the thickness is smaller,the correlation coefficient is bigger,and the linear positive correlation can be established.（2）Through the compaction process simulation analysis,it is pointed out that for the mixed filler with large particle size and no cohesive soil and rock,the dispersion of the porosity value of the filler is significantly reduced after the vibration compaction,and the maximum size and the content of the bulk stone have a significant effect on the filling density of the filler.After compaction,the porosity,with the increase of the maximum particle size and the content of the bulk stone,it decreased significantly.And increases with the increase of the layer thickness,and decreases with the increase of the vibration load.（3）Through the analysis of biaxial compression,it is pointed out that in the mixture of no cohesive soil with large particle size rock,when the stone blocks are in contact with each other to form the skeleton structure,the block stone has a great influence on the strength of the soil-rock mixture,and the compressive failure process can be divided into three stages of elastic deformation,block-stone skeleton bearing and overall failure,and the larger the rock strength,The stronger the strength of the soil-rock mixture;Because of the existence of large particle size stone,the compressive damage of soil-rock mixture under dense state will result in the increase of volume,the higher the strength and the larger the size,the larger the volume increases.