Development of nondestructive techniques of preliminary soil foundations geotechnical assessment

Introduction. Modern nondestructive techniques of wave analysis can be applied for the rapid preliminary geotechnical soil assessment. One of these techniques is Multichannel Analysis of Surface Waves (MASW) which allows to obtain velocities profile of shear waves and an initial shear modulus for upper section at minimal duration and labor costs. But for soil deformation properties assessment it is required a deformation modulus obtained by means of direct technique of plate load test. The purpose of the performed study is assessment of the correlation between plate load test deformation modulus and initial shear modulus obtained via wave analysis. Materials and methods. Plate load tests were carried out for various plates and moduli of deformation were calculated. Deformation modulus adjustment factors were applied to perform a comparative analysis of different sizes plates at 5000 cm2 plate. Wave analysis was carried out by the active method of MASW. Results. During comparative analysis a correlation coefficient was evaluated for two cases: the deformation modulus was determined strictly according to GOST 20276-2012; deformation modulus was determined for the loading interval 0.050-0.125 MPa. In the first case “correlation coefficient-unit weight” indicative dependence was observed. The regression equations for the both cases was presented. Conclusions. Correlation between two types of tests was performed by results of in-situ tests. The proposed empirical regression equation allows to obtain the value of the deformation modulus on the basis of wave analysis data and to perform rapidly a soil foundation geotechnical assessment for the future construction.