Hammer Plate Mean?
A hammer plate is a metal plate on which a sledgehammer is struck to generate seismic waves to conduct seismic refraction surveys. Seismic refraction is one of the methods of geophysics used to investigate subsurface ground conditions for trenchless operations. It utilizes seismic waves sourced from the ground surface.
A seismic wave is energy transfer by way of particle motion and is of three types namely, compression wave, shear wave, and surface wave.
Trenchlesspedia Explains Hammer Plate
The hammer plate is used as a seismic source to generate shear and compression waves. The hammer plate apparatus is placed about 9.1 meters or less from the geophone. This ensures maximum reliability of the reflected wave energy. The hammer plate is struck at 5 to 10 sites within 9.1 meters of the geophones. The seismograph records the generated waves canceling out surface waves and extra noise.
Energy from the struck hammer plate is transmitted through the ground by elastic waves.