The application of grey theory to data processing of fast load test is discussed. According to the grey theory

the author attempts to predict both t-s and P-S curves of the test and obtain the similar settlement which traditionally gained by slow load test. A VB program has been worked out. The contrast between the predicted settlement of an engineering example and the real settlement shows that the prediction of two curves made by grey theory is feasible. The precisions of two kinds of GM(1

1) model used for long distance prediction are estimated; and a conclusion is drawn that the extrapolation of P-S curve more than two or three grades is not accurate enough. The model must be modified when it is used to do long-distance extrapolation.