Gray Theory Prediction In The Low Strain Pile Ultimate Bearing Capacity In Applied Research

Pile foundation has been widely studied because of its practical values, The ultimate bearing capacity of single pile is seriously an important parameter in pile foundation design . The field vertical load test of a single pile is the most basic method of determining the ultimate bearing capacity of it, However, some tests do not meet the standard of the code . This means that in many cases, the piles do not reach the failure . As a result, the exact value of ultimate bearing capacity cannot be achieved.Determining the ultimate bearing capacity by low-strain dynamic testing has been relatively paid more attention by civil engineering circles, because of its special merits, such as short test period, expended little funds, and the good checking effect of piles quality. Now, there are more than ten measures of low-strain dynamic testing have been studied and applied into pile projects. Except for their specialty and scope of application, the common characteristic of those measures is that the parameter of dynamics , such as dynamic rigidity, must be tested , and then some stable linearly relation between dynamic and static rigidity is expected, So can the ultimate bearing capacity obtained . this thought way leaded the result that the basic principle of by low-strain dynamic testing is too narrow, the conversion between dynamic and static rigidity purely depends on empirical formula.However, the way of determining the ultimate bearing capacity is Grey system theory in this paper, by which we directly use dynamic rigidity to determining the ultimate bearing capacity. It is that dynamic (not static) rigidity, who is the true value in fields of pile engineering after all, so can it reflect the true fact of piles and soil. By this way we may get rid of the demerit ,of which low-strain dynamic testing depends on empirical formula . That is to say a new thought about researching the ultimate bearing capacity of the single pile has been referenced.This paper, firstly, introduced the basic theory of low-strain dynamic testing response, and summarized the main factors which influence ultimate bearing capacity of single pile .Secondly, it given parts of information about Grey system theory . Thirdly, on the foundation of some former practical datum of pile foundation, and by Grey interconnect analysis, Grey modeling, remnant identifying, Grey prediction, the paper put forward the Grey prediction of the ultimate bearing capacity of the single pile . Then, the corresponding programs were written by MATLAB language. At last, the model are verified relatively high accuracy and can meet the practical need .