Experimental Study And Numerical Simulation On The Dynamic Consolidation Of The Gravelly Clay Foundation In Mountainous Area

In the foundation treatment project of a certain airport in southern mountain area,there are large amounts of gravelly clay,of which the article size distribution,physical and mechanical properties,permeability and so on are inhomogenous.Also,it contains bigger diameter stones partly and has richer pore-water content but more shallow buried-depth.All of the above features have influence on the effect of the dynamic compaction.What's more,there has been lack of relative research on this issue at present.So,the conducting of research on the gravelly clay foundation,the simulation of the effect of the dynamic compaction and the proposal of applicable dynamic consolidation technology and test method have both theoretical and practical significance.In this essay,research on the gravelly clay foundation and numerical simulation was conducted,relying on the foundation treatment project of a certain airport in southern mountain area.At first,the mechanism of gravelly clay was studied based on the theory of both the saturated and the unsaturated soil.At the same time,relative influence factors were analyzed according to the physical properties of the soil mass itself and the construction parameters.Next,related research was carried out in order.:Construction and experiment scheme were designed after geological survey involving four different energy levels including 1200 kN.m,1600 kN.m,2200 kN.m,3000 kN.m.Many tests were put into practice before and after the dynamic compacting like Shallow-plate loading test,Standard penetration test,Rayleigh-wave test,Excess pore water pressure monitoring,Indoor soil test and Settlement observation,etc,to study the processing effect.And we find that gravelly clay foundation consolidation effect doesn't always go up with the increase of energy level and that there is the most appropriate energy level.The suitable technology of dynamic compaction is also ultimately determined.Meanwhile,through the combination of field test and indoor soil test and the utilization of the knowledge of the Mathematical Statistics,the relevance of Standard penetration test to the physical index of soil mass,to the Shallow-plate loading test and to the Rayleigh-wave test was analyzed;and its empirical formula was also successfully deduced,which could be used to simplify the test scheme of the future large-scale construction and improve test efficiency.Later,based on the above test results,the model of the dynamic compaction foundation of gravelly clay is established to simulate consolidation effect under different energy levels with the application of the FLAC3 D,of which the result was verified through in-situ test.And the formula of the effective reinforcement depth was derived.After the above research,proper dynamic compaction technique of gravelly clay foundation,empirical formula of the relevance in foundation test and the effective reinforcement depth were all finally determined,which could provide experience and theoretical support to engineering practices.