Gray Prediction Of The Vertical Bearing Capacity

The nltimate bearing capacity of a single pile is an important parameter in pile foundationdesign.The field vertical load test of a single pile is the most basic method of determining theultimate bearing capacity of it.However,some tests do not meet the standard of the code.Thismeans that in many cases,the piles do not reach the failure.As a result,the exact value of ultimatebearing capacity cannot be achieved.In respact to this case,this paper proposes to predict it byGrey theory.Grey theory was established by Deng Julong in 1982.The writer combines the Grey theorywith engineering practice.On the presupposition of classification on Q-S curve of the verticalloading test of a sing pile,this paper puts forward SGM and QGM models respectively,andapplies them to practical projects.Their corresponding programes were writen in FORTRAN90language.SGM is fit for the prediction of ultimate bearing capacity of progressive failure piles.According to a lot of data on field static load tests in Xi'an,the paper proposes the ultimate-loading standard of then.By the standard,the writer proposes SGM and RSGM models.SGM isformed on basis of 1-AGO.This model can adjust its mistakes dynamically and checkedautomatically by itself.The typical project analyses the distinguishing feature of SGM and requirements in chossing test data.Many projects in Xi'an verified the similar result of practicalQ-S curve with the predicted one. It can satisfy the project requirement very well.QGM is raised on analysis of Index Law and Grey theory.This model is suitable for theprediction of successive failure piles.This paper offers the steps of building the model.and givesresidaul model RSGM that can increase the predicted precision.Its trait is clarified through a typical sample.In 20 projects its prediction error is below 15%,which testifies that the model hasrelatively high accuracy and can meet the practical need.