Model Tests and Calculations on Bearing Capability of Step-type Section Pile in Loess Base
To study the load transfer mechanism of step-type section piles in loess base,the laboratory model tests and finite element calculations were utilized to analyze the axial force,lateral friction resistance,pile top settlement,and load sharing ratio at various depths of step-type section piles under vertical static load.The study explored the impact of the change in diameter ratio on its operational performance and conducted an optimization design.The results indicate that under the same load,the pile top settlement of the step-type section pile is noticeably less than that of the constant section pile.The best control effect on settlement,with the highest material utilization,is achieved when the diameter change ratio is 0.8～0.9.If the ultimate bearing capacities are equal,the highest material utilization rate for the step-type section pile reaches 1.06 times that of the uniform cross-section pile.The step-type section pile acting as a friction pile,receives support from the soil at the variable cross-section.The soil at the base of the variable diameter portion can bear part of the pile top load,while the pile sides can share a greater portion of the pile top load,thus reducing the load on the pile end soil.The lateral friction resistance is more effectively utilized when the diameter change ratio is 0.8～0.9.When the material usage is the same,the step-type section pile significantly increases the bearing capacity compared to the constant section pile.
step-type section pileconstant section pilevariable diameter ratiomodel testsfinite element analysis
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