Pulse Transmission System for Measuring Wave Propagation in Soils

A soil testing system for measuring wave propagation through soils using a pulse transmission method has been developed. By mounting very sensitive P and S -transducers in the cap and pedestal of a triaxial testing device, the system can even detect strongly attenuated waves that propagate through dry sand. In addition, the wave forms during consolidation and undrained compression tests can be used to investigate the process of soil structure change during deformation. The measured wave velocities are compared with results obtained using the resonant column method and in-situ wave velocity determinations. The pulse transmission method gives a higher S -wave velocity than the resonant column method, especially for clay samples. This difference may result from disturbance of the peripheral part of resonant column specimens. The pulse transmission method gives good agreement with the in-situ velocity measured by the suspension type S -wave logging, whereas the resonant column method gives lower velocity than the in-situ measurement by up to 50% in clays.