Study On Compaction Process Control And Settlement Deformation Of Earth-rock Mixture Of High Subgrade In The Second Bid Section Of Jianyuan Expressway

In the southwest of China,the terrain structure is relatively complex,mainly plateau and mountain.There is a lack of fillings in the local area,and the land resources are rela-tively scarce.The subgrade filling materials are mostly from the earth rock mixed fillings excavated from mountains or tunnels.However,the earth rock mixture is different from the general earth and stone materials,and its material composition is diverse,so it is diffi-cult to carry out quantitative classification and grading evaluation;its engineering properties are complex,and the construction process of excavation,filling,compaction is not easy to control,and no unified standard has been formed to guide the construction.In view of this,relying on the K16 construction site of the second bid section of Jianyuan expressway,this paper understands the construction impact of engineering geological conditions,nature of earth rock mixture,filling process and other factors,conducts in-depth research on the det-ection and compaction control of the high filled subgrade with earth rock mixture on theselected test section,and carries out subgrade settlement monitoring.The main research results are as follows:（1）The field test data and theoretical analysis show that the dynamic deformation modulus E_vdcan reflect the compactness of the subgrade surface layer filler,but the pres-ence of large-size block stone will affect its effect,and the VCV can reflect the structural resistance of the subgrade filling layer more comprehensively.（2）The evenness of the two indexes on the plane and between the rolling passes:the coefficient of variation of VCV index is near 1%,the coefficient of variation of EVD index under the condition of mixed filler on the plane has exceeded 10%,and the coefficient of variation of EVD index under the condition of rolling passes is near 10%.It is recommended to compact the mixed filler evenly on the plane:when the loose paving thickness on the site is 50cm,it is recommended to control the mixture of class a filler and class B filler by 2:2～3:2;when the loose paving thickness is 60cm,it is recom-mended to control the mixture of class a filler and class B filler by 4:2～5:2.Suggestions for uniform compaction between filling times:it is recommended to stack four times for multi class a filling（relatively small boulder content）and five or six times for multi class B filling（relatively large boulder content）.Suggestions for uniform compaction between filling times:it is recommended to stack four times for multi class a filling（relatively small boulder content）and five or six times for multi class B filling（relatively large boulder content）.（3）Based on the test data of two subgrade compaction indexes（VCV index and EVD index）,this paper studies the influence of slope topography,loose paving thickness of filling layer and filler type on subgrade compaction effect.（4）Through the comparative analysis of VCV value and EVD index in the test section,it is pointed out that there is a linear relationship between the vibration compaction value a-nd the conventional index,and the control standard of the continuous compaction test index is determined to complete the control of the subgrade compaction uniformity,compaction quality and compaction stability in the test section.（5）subgrade settlement:The settlement value of the cross-section is roughly distributed in the middle of the large and the small at both ends.The settlement amount at both ends of the pipe orifice is small,and the settlement amount of the roadbed is large mostly near the middle line of the roadbed.With the increase of the observation time,the settlement change rate of the cross-section of the roadbed decreases.When the observation time reaches 200days,the average settlement rate of the left and right slopes decreases to about 1mm/month.