Experimental Study On Dynamic Compaction Of High Fill Subgrade In Mountainous Areas

With the development of urbanization in China,more and more highways are developing in mountainous areas.Especially for mountainous highways with ravines,steep valleys and complicated geology,high fill subgrade is the main form of subgrade for mountain highways.In order to ensure the stability of high fill subgrade and meet the requirements of post-construction settlement,in addition to the stratified roller compaction construction,the dynamic compaction method is an effective technical measure to improve the compaction of the subgrade.Based on Ziwang Highway in Guizhou and Pingzan Highway in Shijiazhuang,this paper studies and analyses the settlement mechanism of high fill subgrade and the method of dynamic compaction.The main research contents and achievements are as follows:?Combining with the domestic and foreign literature,this paper briefly introduces the settlement problems and characteristics of high fill subgrade in mountainous areas,and expounds the strengthening mechanism,effective strengthening depth and numerical simulation research of dynamic compaction method.Through analysis,it is concluded that dynamic compaction method can improve the compaction degree and bearing capacity of high fill subgrade in the construction process,so as to achieve the purpose of reducing post-construction settlement.?The definition and characteristics of high fill subgrade are introduced.The causes of settlement of high fill subgrade and its settlement mechanism are analyzed in detail.It is concluded that the settlement of high fill subgrade is different from that of ordinary subgrade,which causes settlement.The reasons include high height,heavy self-weight,insufficient compaction,and large differences in fillers.?When dynamic compaction test is carried out on the spot,the relevant data are collected and analyzed,and the variation law of dynamic stress along horizontal and vertical directions is obtained.The difference of uplift around the rammer is caused by different ramming energy,and the relationship between the number of ramming times and the amount of ramming settlement in the field test.?The field measured data of high fill subgrade on Pingzan Highway are simulated and compared by ABAQUS software,which verifies the accuracy of the numerical simulation results.Through the numerical simulation of post-construction settlement,it is concluded that the effect of dynamic compaction is remarkable.Through numerical simulation of different tamping energies,the effective reinforcement depth and the layered filling height in dynamic tamping construction are determined.