Research On Bearing Capacity And Settlement Property Of Single Pile In Loess Under Axial-Load

The bearing capacity and settlement property of single pile under axial load is an important subject in pile foundation theory research. Domestic and overseas scholars have achieved a series of valuable conclusions in this field during the long term's exploration. While, many problems are still left for profound research due to the complication of inter-action between pile and surrounding soil. In this paper, depending on the enormous 356 pile testing date detailed with soil and pile parameters and P~s curves, covering xi'an and adjacent areas, we analyzed the load transmission mechanism of pile in loess foundation, and proposed a kind of hyperbolic load transmission function between pile and it's neighboring soil. Meanwhile, we created a mathematical model to predict P~s curve and bearing capacity of single pile.By analyzing the compacting effect caused by pile-sinking of pressed pile in loess and it's influence on bearing capacity and settlement, two parameters, Kc and Ke are introduced to modify the soil cohesive c and deformation modulus Es. The experiential formula between Kc and base resistance q from CPT and, the relationship between Ke and C#(strength of concrete) are also created by fitting 94 pressed pile testing date. Based on analyzing the compacting effects caused by driving pile in loess and it's influence on bearing capacity and settlement, another two disturbance parameters, c and e , are proposed for multiplying respectively the parameters of soil cohesive c and deformation modulus Es to reflect thiseffect. By fitting 51 driven pile testing date, we created an experiential formula between the e and R(the modulus ratio between pile and surrounding soil), also an experiential formula between the c and base friction resistance fs/pa from CPT of pile surrounding soil. At last, the load transmission property of cast-in-place piles, the developing cause of friction resistance and base resistance, and some factors which influence pile's bearing capacity and settlement are analyzed. Then, we introduced two parameters, e and c to represent the disturbing effect in pile construction on parameters of modulus Es and cohesive c, which determined by the pressed piles. By fitting 106 testing date of cast-in-place piles, the experiential formula between the e and C# as well as L/d(ratio of length and diameter of pile) and, the experiential formula c and base resistance qc/ pa from CPT of pile surrounding soil are given. Finally, we put some examples to testify this theory.