Study Bearing Capacity Of Revolving Digging Cast-in-Place Bored Pile Through Load Transfer Method

Revolving digging cast-in-place bored pile is individual types of pile in loess areas, borehole wall is asperity what drilling by utilizing the technique for revolving digging, friction resistance along the pile is raised. This paper based on some typical static loading example in the east suburb of xi'an, Thorough analysis the process of load transfer, variety regulation, load-subsidence of single pile on axis load, respectively to unsaturated loess layer of the upper part and saturated loess layer of lower parts to should of the exertive characteristic of friction resistance along the pile make the further analysis, according to the different soil layer appearing different relation of stress-strain, The improved load transfer model that put forward the friction resistance along the pile and subsidence displacement—With the soil body variety of friction resistance along the pile trilinear model. That model makes use of stiffness coefficient ks2i a pile soil body at stage of elastic-plastic (s1i～s2i)may plus, minus or zero, unify linear-elastic and full plastic model, softening model and hardening model.Present the slow side form for the curve of Q-s, without obvious breakage characteristics pile foundation and those to superstructure of the extremely impressionable to subsidence, We should control them according to allow settlement of top pile. This paper gives an analysis method of calculating vertical bearing capacity of pile foundation according settlement of top pile, utilizing the load transfer function advanced from this chapter which 'Deepening study of load transfer function model'- friction resistance along the pile improved trilinear model, by dint of Atkins' iterative methods, calculating load of top pile under the circumstances elastic , elastic-plastic o r plasticity respectively to be placed in the settlement of top pile. deduce a series of formula that settlement of top pile and bearing capacity, in order to more overall emulating function mechanism of pile and soil, thus realize the ideal that settlement of top pile control bearing capacity .Last, carry on a verification to the improved trilinear model. During analysis the data of static loading test of teaching building of south suburb in xi'an, where is loess areas, to pile deformation of the end of elastic straight line as elastic deformation critical value s1i, then synthesizing all point draw up to a straight line whose the trend is more steady in the stageplasticity, the intersection point of this line and the curve of qs~s relation thorough actuarial measurement as plastic deformation critical value s2i. The stiffness coefficient of friction resistance along the pile ksli and ks2i take the value form gradient of at stage of elastic and elastic-plastic. The development trends of curve qs~s relation of main soil layer fits improved trilinear model in this paper.Put forward this text according to repeatedly for sinking declining deal control loading dint on behalf calculation method to experiment the floor the solid a verification with the some teaching in the south suburb of Xi' an, the calculating load carries the value and prognosticate physically the value proceed the comparison, result Q~s the curve of s than for fit together. And refrain from rash action the speed quicker. Explaining this text method can used for the leading engineering practices, having the good fulfillment value.