| With the rapid development of the country,China’s urbanization process is deepening,more and more large-scale engineering projects are developing in mountainous areas,and the geological conditions are relatively complicated in mountainous areas,which often brings many problems to the construction.For mountain road engineering projects,it is often necessary to face the problem of deep excavation and high filling.Considering the economy and the difficulty of construction,mountain road projects often use explosive gravel to fill the subgrade,and use the dynamic compaction method to reinforce the rockfill subgrade.However,as far as the development of dynamic compaction is concerned currently,its theoretical research is far behind the practical application,and it relies more on construction experience in practical applications.This has certain limitations and disadvantages for engineering applications of dynamic compaction.Based on the background of a mountainous highway project in Guizhou Province,combined with the relevant properties of large-diameter gravel,block analysis of explosive gravel and theoretical research of dynamic compaction,by using the particle flow software PFC2D,the numerical simulation analysis of dynamic compaction on the rockfill subgrade in this paper.This paper mainly studies from the following aspects:(1)Analyze the subgrade rockfill materials commonly used in mountain road engineering at present,and briefly introduce the classification and engineering characteristics of rockfill materials.Combined with the distribution law and prediction model of explosive gravel,the blasting design parameters of a highway in Guizhou Province,and the basic requirements for subgrade filling,predicts the explosive gravel block distribution of the project,and verify by the actual project.(2)This paper introduces the basic principles of particle flow in detail from three aspects:basic assumption,calculation principle and contact constitutive model.The indoor large triaxial test was carried out according to the similar grading method to obtain a stress-strain curve.Then a biaxial test model is established to analyze the correlation between mesoscopic parameters and macroscopic mechanical properties based on PFC2D,and the parameters of the large three-axis test are calibrated to obtain the relevant mesoscopic parameters.(3)According to the background engineering data,the particle flow model of large-diameter rock-filled roadbed and tamper is established based on the particle flow software PFC2D,and the dynamic compaction process of rock-filled roadbed is simulated.Combined with surface subsidence,soil displacement and effective reinforcement depth,the effect and regularity of dynamic compaction were analyzed in detail.(4)According to orthogonal test method,orthogonal analysis was carried out to obtain the primary and secondary factors affecting the effect of dynamic compaction for the three parameters of tamper width(the area of tamper bottom under actual three-dimensional conditions),hammer weight and tamper drop distance.Combined with orthogonal analysis,the three parameters of tamper width,hammer weight and tamper drop distance were analyzed by single factor simulation,and the influent law of various factors on the consolidation effect of dynamic compaction was obtained.Figure[36]table[18]reference[46]... |
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