Research And Application On The Prediction Ultimate Bearing Capacity Of A Single Squeezed Branch Pile Based On The Grey Theory

The field vertical load test of a single pile is one of the best and intuitionistic method of determining the ultimate bearing capacity of a single pile, it's also the prescript method of our country's criterion. But in many cases we can't destroy the testing pile, achieve the integrated curve of the Q-S and the exact value of ultimate bearing capacity of a single pile for the limit of the testing equipment, expenditure, work plan and the condition of the terminate testing ect.So it is an event of significance to acquire the prognosticate data through the finite data which obtain by the field vertical load test.The Squeezed branch Pile is a kind of new-type pile foundation which developed at the beginning of the 1990s. It has made the good economic and social benefits for its higher bearing capacity and low settlement. But little correlative researches had been done because of the complex load transferring rules of this kind pile. In respect to this case, this paper proposes to predict the ultimate bearing capacity of squeezed branch pile by Grey system theory. According to the Grey system theory, this paper proposes the non-same step GM(1,1) model which can be applied to predicate the ultimate bearing capacity of squeezed branch pile. And applies them to practical projects, their corresponding programes were written in MATLAB7.01 language, and predicate the settlement of squeezed branch pile based on the curve of piles in different load-level. The results show that the non-same step GM(1,1) model can meet the project requirement. And the one to nine degree GM(1,1) is the best for the ultimate bearing capacity prediction.At the same time, based on the results of static loading test, the influence factors of the ultimate bearing capacity of squeezed branch pile are analyzed by gray system theory in this paper.The analysis result shows that the correlation index order is plates resistance, shaft resistance and toe resistance.At last, use the Hyperbola method to predict the Ultimate bearing capacity of single pile and compare with the prognosticate results which by Grey method, the predicated results obey the Gaussian distribution and meet the demand of the project.