| 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.As a way to determinate the bearing capacity of pile, prediction method has been widely used these years. Its economic effect is very clear, definite in meaning, simple in calculating, wonderful in the modeling effect and good in explanation, so nowadays it is becoming a practical tool in the field of engineering and economic management. Compared with traditional methods, it has definite advantage whether in testing equipment, work condition or expenditure for the testing. Using prediction can give the most technical economic effect, providing design with reasonable data of pile's bearing capacity, bringing into play pile's bearing capacity completely, thus can save the engineering cost.This paper, firstly, introduces the transferring machanism of load which the pile is undergone and summsarize the factors Which influence the ultimate capacity of single pile in loess. Secondly, it given parts of information about Grey system theory.Thirdly, a group of prediction models that can predict the ultimate bearing capacity of a single pile are established by the gray system theory, including Non-equi step GM(1,1) model (NEGM), Self-Adjusting NEGM and Self-Adjusting NEGM with Residual Error Modification. Then, the corresponding programs are written by MATLAB language. And a practical engineering data verifies that these models can meet the project requirement. Moreover the Self-Adjusting NEGM with Residual Error Modification has the most high accuracy. |
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