SEISMIC REFRACTION SURVEYING IN SOILS WITH VARIABLE PROPAGATION VELOCITY.

A procedure is described for the analysis and interpretation of data from a seismic refraction survey of soil with a linear variation of wave propagation velocity with depth, with a deeply embedded shot point, and with refraction at the air interface, as well as at the lower boundary. The problem is solved analytically and a digital computer is employed to develop a series of charts which give arrival times at various distances as a function of soil characteristics for media with widely varying velocity distributions. The interpretation procedure consists of using these charts to determine the soil characteristics which agree most closely with the recorded response. Three applications are illustrated by the use of field data from a hydraulic landfill composed of maintenance dredgings.