Study On Design Theory Of Dynamic Replacement Stone-piers Composite Foundation And It's Applications In Engineering

Dynamically formed stone column compound foundation is developed on theory basis of dynamic compaction and composite foundation. Both the advantages of stone columns and dynamic compaction were inherited by dynamically formed stone column compound foundation. Its construction technology is simple and convenient,with characteristics of both dynamic replacement and drainage consolidation at the same time. So dynamically formed stone column compound foundation is widely used in weak soil treatment.Based on a comprehensive analysis and a summary of the development situation of dynamic compaction technology, the engineering properties of weak soils and the reinforcement mechanism are analyzed in-depth. Reinforcement mechanism and these design parameters of effective reinforced depth, compaction energy, times number, interval, point spacing are analyzed.On these basis and combined with the Huanhe Road project in WuHan and other many examplesofdynamically formed stone column compound foundation, replacement rate formula of dynamically formed stone column compound foundation is modified in this paper. The column has an effect of bulge when hammered as a result of granular structure. So the primary replacement rate is not precise.Now we can express it like this: m = V_p/V .And it can be determined by added a correction factor: m =αA_p/A .we can reduce the diameter when we design like: d' =βd ,β=0.70-0.85.it can also attain the same replacement ratio,and have no waste.through the volume ratio of column and soil rather than through model comparison and calculation by FEM of MIDAS. The research in this paper is of direct engineering significance and project cost can be reduced to a large extent.At last, combined with the Huanhe Road project example the author participated in WuHan and based on the summaries of so many engineering practice, a comprehensive introduction and a systematic description of the construction and subsequent quality monitor program of dynamically formed stone column compound foundation are conducted. It is showed a ground treatment program of good effect and rationally economy through practice.