Effect of Source Energy for SASW Testing on Geological Sites

A number of Rayleigh wave tests were performed on two geological sites by employing a cylindrical mass of 65 kg dropped from a height ranging from 1 to 4 m. For each test, the mass was dropped freely either (1) directly on ground surface, or (2) on a steel circular base plate kept on the ground. Various combinations of source to first receiver distance (S) and receiver spacing (X) were employed. It has been noted that the value of λ _max increases continuously with an increase in the source energy; where λ _max refers to the maximum wavelength up to which the shear wave velocity profile can be obtained with the usage of the spectral analysis of surface waves tests. The inclusion of the steel base plate below the dropping mass leads to a further increase in the value of λ _max . It is also observed that, for the same height of fall, a ground stratum with relatively greater stiffness tends to provide an increased value of λ _max .