The Seismic Cone Penetration test (SCPT) consists of measuring the travel times of body waves propagating between a wave source and the ground surface and an array of geophones in an in-situ seismic cone penetrometer. These body waves comprise shear waves (S-waves) and compressional or primary pressure waves (P-waves). Performing this measurement during CPT soundings is much quicker and less expensive that standard crosshole tests or downhole tests.
The seismic cone penetration test (SCPT) combines the seismic downhole method and the logging capabilities of the cone penetration test (CPT) to provide rapid, reliable and economic means of determining soil stratigraphy, relative density, strength, shear and compressional wave velocities. From interval shear wave velocity and the mass density of a soil layer, the dynamic shear modulus of the soil over a specific interval may be calculated.
The dynamic shear modulus is a key parameter for the analysis of soil behavior in response to dynamic loading from earthquakes, ice, vibrating machine foundations, waves and wind.
Seismic waves generated on the surface are detected downhole by three geophones mounted inside the penetrometer, a simple method requiring no field assembly. Recording multiple seismic tests and CPT data in a single push contributes to site information gathering and project efficiency. CPT seismic waves traces have been recorded at depths of up to 300 feet below ground surface. Variations in seismic characteristics are easily recognized by plotting several data points versus depth.
The cone penetration test is briefly paused to conduct seismic tests at specific depths. Individual seismic tests include the recording of two opposing shear S-waves and one compression P-wave. Each seismic test is graphically compiled to create a profile for seismic wavespeeds, damping characteristics, and soil strength parameters.
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