Model Test Research On The Compacting Effect Of The Jacked Pressure In Sand Pile Using PIV Technique

The research on deformation of pile soil is a method research on soil compacting during pile driving.Analysis of deformation field can get some conclusions of deformation during pile driving.A modeling test system based on particle image velocimetry(PIV)was improved for studying the deformation characteristic of the soil around piles during the static pressure pile driving.During the whole process,a CCD(charge coupled device)high-speed industrial camera and Davis8.0 series of acquisition software were used to capture images of the soil deformation around piles,and the PIVview2 C image processing software was used to obtain the deformation field distribution of the soil around piles.For further analysis of the deformation characteristic of the soil around piles during the static pressure pile driving,so the displacement field,shear strain and volumetric strain field were analyzed at different stages in the process of single and double piles driving to 20 cm.The test results are as follows.(1)Deformation test results show that in the process of single pile driving,with the pile end Pierce,the total displacement on both sides of the pile gradually transfixion elliptic ring,inclined expansion to downward on lower part soil.The biggest vertical and horizontal scope of total displacement field were 6.7 D and 6.3 D.Shear strain contours showed that in pile-sinking process shear stress were respectively to form two rows of run-through shear strain fields.The row which is formed along the pile tip settlement period,expand on both sides of the inclined upward respectively.Another is the lower part of the pile end,the shear strain fields along the pile tip respectively inclined downward expansion,maximum shear strain curve basically for the hyperbolic shape.The biggest shear strain fields influence scope of vertical and horizontal were 4.5D and 4.7D.The volume strain field is symmetry.It form two independent deformation field in one part.Above is greater than the following in terms of horizontal scope.(2)In the process of double piles(intervel 2D)driving,The biggest vertical scope and horizontal scope which under pile end of total displacement field were 6.0D and 5.8D.Total displacement at pile end on both sides of the obvious asymmetry,The total displacement field is larger on the left side of the pierce pile.The total displacement is formed on the right side of the embedded piles at 2.3 stages.Shear strain is asymmetric.It is formed in two rows at the pierce piles on both sides of the upper and lower at stage 1 and 3;It is formed not only on both sides of the penetrated pile at stage 2,but also formed up and down two rows on the left of embedded pile.The biggest horizontal and vertical scope that under the pile end were 4.7 D and 5.0 D.Volumetric strain field on both sides of the pile respectively to form two independent part elliptical ring.The biggest horizontal and vertical scope that under the pile end were 5.3 D and 5.0 D.(3)In the process of double piles(intervel 4D)driving,the total displacement field is basically symmetrical on both sides of the pile end,The biggest vertical scope and horizontal scope which under pile end of displacement field were 6.7 D and 7.0 D,Displacement is formed on the right side of the embedded piles at 3 stages.Shear strain field are basically symmetrical adjustment type.The biggest horizontal and vertical scope that under the pile end were 5.0 D and 5.0 D.It distributed on the left side of the embedded pile.The volume field on both sides from two independent part symmetry elliptical ring.