Filed Research On Settlement Characters And Construction Technology Of Ram-Compaction Piles With Composite Bearing Base In High-Speed Railway

Ram-compacted piles with bearing base is a new subgrade reinforcement technology in the 1990s of China. Because of its good economical efficiency and applicability, it has been widely used in subgrade treatment of buildings, while the application in railway subgrade begins only in recent years. There are significant differences between the two methods, first of all, the railway roadbed is considered to be a flexible subgrade traditionally, but the building subgrade is a typical rigid subgrade; secondly, the load of building is static, while the railway subgrade load is dynamic;thirdly, the no ballast track high-speed railway subgrade settlement after construction requests generally no more than 15mm, of which standard is much higher than the building subgrade. There are lots of relatively perfect theories and methods about the property analysis of composite subgrade under rigid subgrade, of composite subgrade stiffness, but the theories and methods about the flexible composite subgrade are still immature.Through reorganizing the theory achievement of the ram-compacted piles with bearing base, summarize the formation theory and the effective diameter formula about expansion head, the supporting capacity computation and the settlement computation about the ram-compacted piles with bearing base, then summarize and consummate the research about the ram-compacted piles with bearing base, to instruct the ram-compacted piles with bearing base designning.In this paper, combining field tests of the ram-compacted piles with bearing base under the flexible subgrade used in high-speed railway, a variety of field observation data is analysed for studying the settlement deformation theories of railway subgrade reinforcement area and the substratum, to verify and enrich the current theory of the ram-compacted piles with bearing base.Reorganizing the-spot record about the ram-compacted piles with bearing base in high-speed railroad roadbed project construction craft, and summarizing the problem about the construction main point to instruct the ram-compacted piles with bearing base in future work on the railway application.Numerical simulation experimentations are carried out on the bearing performances of the ram-compacted piles with bearing base by using the finite element method (FEM) software of PLAXIS. It proves to be correct and rational on the basis of comparing with the field monitoring data. Based on this, carring on the analysis to the compound settlement of ground rule, and the soil body and the head of pile stress assignment and the settlement carries on the contrastive analysis on the pile, to promulgate its action mechanism, and analysis its influence effect.