The Influence Of The Centrifugal Model Test Of Saturated Sand Preparation Method Research

In recent years,geotechnical centrifuge test technology is becoming more and morewidely used.And it has become the important research means of geotechnical engineering.At the same time,the model of sample preparation in centrifugal tests also gradually get attention,and some scholars has obtained certain research results.About sample of centrifugal test preparation methods,at present there are mainly two common sample preparation methods that are sand rain and stratified the compaction.Although stratified the compaction method is a commonly used method of sample preparation,the studies of the compaction method theory is not much.In addition,it is not got enough attention that different sample preparation method make diffeerent centrifugal model test results.In view of these problems,this paper has carried out the following research work:(1)Model sample preparation stage,this paper explores the influence factors of compacting sandy foundation model samples.Main consideration of the influence factors including compaction mode,compaction layer number,relative density,initial moisture content and so on.The uniformity of sandy foundation model samples is the evaluation indexes of quality.And uniformity of the sample is tested by CPT.It is verified that sand rain method prepare sandy foundation model,then contrast sand rain with compaction.The test results show that the compaction method and number of compaction layer are the main factors influencing the uniformity of the sample preparation.And relative compactness(Dr=30%?50%?70%)and initial moisture content(w=0%?3%?5%)don't have obvious effect on uniformity of sample preparation.This paper prepare coarse sand sample and standard sand sample by compacting,then analysis the effect of grain composition on sample preparation.Results showed that the sand that the particle size distribution is dispersed is difficult to prepared the good uniformity sample by compaction.In a word,controling the appropriate compaction factor,the compaction method can prepare good uniformity foundation model using sand that the particle size distribution is concentrated.(2)Centrifugal model test stage,using different sample preparation method respectively prepare sandy foundation model samples,then complete the shallow foundation bearing capacity experiment by the drum centrifuge.And this paper analysis the effect of different sample preparation method on the foundation bearing capacity by load-settlement curves.The main methods of the sample preparation conclued dry-tamping,moist-tamping,sand rain method and a special kind of moist-tamping.And relative compactness of the foundationmodel is 50% or 70%.The initial moisture content of sample that is prepared by moist-tamping is 3% or 5%.This paper use finite element analysis software ABAQUS to simulate Centrifugal test,then contrast numerical simulation results with test results about load-settlement curves.The test results show that the different sample preparation method has obvious influence on the centrifugal model test results.For the same size and relative compactness foundation model sample,dry-tamping make a higher bearing capacity of foundation model.Initial moisture content(w=3% ? 5%)don't have obvious effect on centrifugal model test results.Foundation models which are parared by dry-tamping and moist-tamping have similar bearing capacity.Contrasting static triaxial test results,centrifugal model test results have similar conclusion.Numerical simulation results of ABAQUS show that test results of moist-tamping is nearest to numerical calculation.