Study On Reinforcement Range And Mechanism Of Dynamic Compaction For Foundation Filled With Soil-aggregate Mixture

With the rapid economic development of China,building airports in the mountain area becomes an urgent requirement.The construction of airports in the mountain area faces many problems.For example,it is needed to blast stones and level the valley in the large scale of airport construction because of the lack of plain in the mountain area,which results in the poor gradation rock mixture foundation.The poor gradation rock mixture foundation has many shortcomings,such as large settlement and poor bearing capacity of foundation,and thus it should be improved by the dynamic compaction method.Although the dynamic compaction is an important foundation method having many advantages,it involves dynamic problem of elastic plastic medium.It is thereby difficult to study the theory of dynamic compaction.In this thesis,based on others’ achievements,the reinforcement range and the mechanism of dynamic compaction are analyzed by FEM(finite elementary method)systematically,including:Firstly,the three dimensional finite software of nonlinear is used to simulate the process of dynamic compaction on the foundation filled with soil-aggregate mixture.The comparison between the simulated results and the specific project examples proves the reliability of the numerical analysis.Moreover,basic characteristics of dynamic compaction are analyzed.Secondly,with essence of dynamic compaction as the starting point,the previous evaluation criteria of dynamic compaction range are reviewed,and their limitations are analyzed.Based on the analyzed results,the controlled volumetric strain is chosen as the evaluation of the reinforcement range,and used to measure the dynamic effects.Thirdly,all the factors impacting the dynamic compaction are analyzed.For each factor,law of dynamic effects is studied scientifically,such as radius of rammer,tamping times,weight of rammer and height.Fourthly,the influence of external loads on dynamic compaction is analyzed.Compared tamping energy and tamping impulse,impulse is more reasonable,which has a one to one relationship of dynamic effect.If other parameters are unchanged,larger impulse leads to better result.At last,the formula of reinforcement range is proposed on the summarization of the various factors and the dimensional analysis.The calculated results of the formula is approximately equal to measured results,and can be extended to similar projects.