Influencing Factors And Sensitivity Analysis Of Bearing Behavior Of Composite Foundation Of Pipe-pile With Holes & Cap

Previous research on composite foundation of pipe-pile with holes&cap is mainly focused on indoor model test and corresponding numerical simulation.There still exists a gap on the study on the bearing behavior of the composite foundation of pipe-pile with holes&cap under the parameters of numerical simulation engineering.Therefore,it is necessary and meaningful to study the influence and sensitivity analysis of the influence factors of the engineering practice parameters on the change law of the bearing behavior of the composite foundation of pipe-pile with holes&cap.In this paper,the ABAQUS numerical simulation method is used to study and discuss the influencing factors and sensitivity of bearing behavior of the Composite Foundation of pipe-pile with holes&cap.The main contents and conclusions are as follows:(1)Numerical simulation was carried out on the basis of the length-diameter ratio,cap-diameter ratio,thickness-diameter ratio,pile aperture ratio,hole diameter ratio and comprehensive factor load settlement of single perforated capped-pipe pile composite foundation;and sensitivity analysis was done on the basis of influence of the pile shaft force,soil pressure of pile,pile side frictional resistance,pile-soil stress ratio and so on.1)The total settlement of the composite foundation of pipe-pile groups with holes&cap with the same length to diameter ratio decreases by 1/3;The optimum length diameter ratio of the composite foundation of pipe-pile groups with holes&cap is 30,and the ratio of length to diameter should not exceed 40,and if the ratio of length to diameter is too large,the effect of soil between piles is very small,so the bearing capacity of composite foundation can not be improved.2)The effect of the cap diameter ratio on the bearing behavior of the composite foundation of pipe-pile groups with holes&cap is significant.With the increase of the ratio of the cap diameter,the total settlement of the composite foundation of pipe-pile groups with holes&cap and the axial force of the pile body are gradually reduced.The optimum cap diameter ratio of composite foundation of pipe-pile groups with holes&cap is 3.3)The greater the ratio of thickness to diameter,the greater is the settlement of the single pile Composite Foundation of Pipe-pile Groups with Holes⋒When the value of the thickness ratio is 0.6,the soil bearing capacity between the pile and the pile is suitable,and the bearing capacity of the composite foundation is improved.4)The pile body with different pile diameter ratio will produce different degree of stress concentration;the ratio of the pile diameter is within the range of 10 to 12.5,and the bearing capacity of the foundation with a perforated capped pipe pile can be fully realized.5)The smaller the diameter ratio between the pile holes,the smaller is the total settlement of the Composite Foundation of Pipe-pile Groups with Holes&Cap and smaller is the axial force of the pile body.The greater the ratio of the diameters of the pile holes in the middle of the pile,the smaller the friction resistance of the pile side is,and the smaller the ratio of the diameter between the pile holes at the bottom of the pile is,the greater the friction resistance of the pile side is.(2)Under the vertical load,the ratio of pile-to-diameter between pile groups significantly affects the bearing behavior of Composite Foundation of Pipe-pile Groups with Holes&Cap.When the ratio of pile diameter is 4,the effect of group pile is not obvious.It is similar to forming a big "square pile" between pile groups to bear the upper load;the aspect ratio of 8 is the critical pile spacing diameter ratio of pile group pile Composite Foundation of Pipe-pile Groups with Holes&Cap,and the ratio of pile diameter ratio 8 is the best inter pile diameter ratio.