Pressuremeter Modulus and Limit Pressure of Clayey Soils Using GMDH-Type Neural Network and Genetic Algorithms

Pressuremeter modulus ((E_{M})) and limit pressure ((P_{L})) are used for the calculation of the settlement and bearing capacity of foundation respectively. As the determination of these parameters from pressuremeter test (PMT) is relatively time-consuming and expensive, various empirical correlations have been proposed to correlate the (E_{M}) and (P_{L}) to other soil parameters. For the existing equations are incapable of estimating these PMT parameters well, in present research group method of data handling type neural network is used to estimate the (E_{M}) and (P_{L}) of clayey soils. The (E_{M}) and (P_{L}) were modeled as a function of three variables including the moisture content ((omega)), plasticity index and corrected SPT blow counts ((N_{60})). A database containing 51 data sets have been used for training and testing of the models. The performances of proposed models are compared with those of existing empirical equations. The results demonstrate that appreciable improvement with respect to the other correlations has been achieved. At the end, sensitivity analysis of the obtained models has been performed to study the influence of input parameters on model outputs and shows that the (N_{60}) is the most influential parameter on the PMT parameters.