Study On In-suit Test And Correlation Of Dynamic Compaction Foundation Bearing Capacity And Deformation Modulus

Techniques of foundation treatment have been widely used in civil engineering, compared with the other methods of foundation treatment, dynamic compaction method has the merits of remarkable effect for strengthening, simple equipment for construction, fast construction and less construction cost, etc. Lots of theoretical researches were carried out in recent years, but they were usually focused on studying of mechanism and calculates influence depth of dynamic compaction, it rarely studied on bearing capacity and deformation modulus of dynamic compaction foundation. Up to now, there are no systematical theory and the agreed opinions for the designing and application of the dynamic compaction and the degree of improvement for dynamic compaction is left to be determined by way of testing after treatment. So, further researches aimed to the study on application of test techniques for bearing capacity and deformation modulus of dynamic compaction foundation is essential desired to promote the level of application.Firstly, in this paper, the author put forward a set of comprehensive method of detecting bearing capacity and deformation modulus of dynamic compaction foundation, namely, select plate loading test and standard penetration test to detecte soil foundation, plate loading test and dynamic penetration test to detecte gravelly soil foundation, in order to decrease the number using PLT or use the small scale PLT, because PLT costs longer time and higher cost. Statistics methods and data processing of in-suit test were proposed also.Secondly, because of not reaching degree of failure on plate loading test(PLT), it is usually difficult to evaluate characteristic value of bearing capacity for dynamic compaction foundation. In this paper, the authors have introduced the grey theory prediction methods to predict the tendency of load-settlement curve, based on the GM (1,1) model in the grey system theory and partial data measured from the former steps of PLT. The characteristic value of bearing capacity for dynamic compaction foundation is evaluated by this method. Practical engineering examples verify that this model can meet the project requirement.Predict results can be referred for standard penetration test and dynamic penetration test constructing empirical relationships.Lastly , the set of method of comprehensive method that put forward in this paper was applied to engineering practice, combining with collected engineering data, the relationships between two indexes (characteristic value of bearing capacity f_αk and modulus of deformation E₀)of PLTand blow count N of standard penetration test were constructed in soil dynamic compaction foundation ; the relationship between characteristic value of bearing capacity f_αk of PLT and blow count N_63.5 of dynamicpenetration test was also constructed in gravelly soil foundation . These relationships can be referred for similar dynamic compaction foundation detecting and evaluating through compare with relationships of natural foundation.