Executive Summary : | Soil characterization is crucial in geotechnical engineering, and the Standard Penetration Test (SPT) is a commonly used method. However, the SPT-N value provides unreliable information about dynamic soil properties, making it necessary to develop complementary techniques. One such technique is studying seismic waves, which can generate near-surface seismic waves that contribute valuable information on Earth's subsurface structure. Indian researchers are currently using costly foreign software like PLAXIS, FLAC, and ABAQUS to model the wavefield. This study aims to develop a seismic SPT method that accurately estimates dynamic soil properties. The proposed method uses 4-8 3D seismographs along the ground surface to capture waves generated by the SPT hammer, yielding information about dynamic soil properties like layer depth, shear modulus, density, bulk modulus, and Poisson's ratio. A novel "Sliding Fourier Transform (SLFT)" based time-frequency processing tool is developed to identify the exact arrival time of seismic waves. The method requires no human input, eliminating misjudgment-related errors. A 3D numerical subsurface modeling algorithm is also proposed to simulate seismic waves generated by the SPT hammer, reducing uncertainties and improving field test accuracy. The first-of-its-kind Make in India wavefield modeling software for SPT will be released for Indian companies and researchers. This proposal will enable traditional SPT to predict dynamic soil properties, enable users to numerically model the test for validation, and empower the Atma Nirbhar Bharat initiative. |