Comparison of pressuremeter and plate loading results to determine the deformation modulus in fine-grained soil

The pressuremeter test (PMT) and plate load test (PLT) are principal in-situ experiments for measuring soil stiffness and deformation parameters. Although the PLT can be costly and complicated at great depths the PMT can be easily done in a borehole. Empirical equations linking the parameters from these tests can be useful for cross-checking the parameters obtained by the two methods and can reduce costs. In the present study, PMTs and PLTs were carried out on fine-grained soil from two sites in Iran. The pressuremeter modulus (E_PMT) and limit pressure (P_L) from the PMT and plate load modulus (E_PLT), subgrade reaction modulus (K) and reload modulus (E_r) from the PLT were determined and the relationships between them were investigated. A reliable and significant statistical model for these empirical equations has been was proposed. It was found that the average E_PMT was about 25% higher than that of the E_PLT and an exponential relationship could be determined linking the parameters at each site. A logarithmic relationship has been proposed between E_r and E_PLT. The mean absolute percentage error (MAPE) for calculation of the E_PLT, K and E_r for both sites was less than 15.14, indicating that the proposed equations estimated their values with good accuracy. Comparison of data from PLTs and PMTs in another area recorded a MAPE of less than 13.08.