Home

CPT Cones and Cone Parameters

Cone with caliche coating
Minnesota GeoServices uses three types of cones, standard CPT cones, seismic cones and specialty cones as described below. All of our cones (standard, seismic and specialty) are 15cm2 area cones and are advanced using 36mm CPT rods without friction reducers. If necessary, 56mm casing is used to support the rods through soft surficial soils. The total pushing force of our CPT rigs is sufficient for nearly all soil investigative work in our standard CPT practice (up to approximately 140 feet).

The addition of seismic geophones to the CPT is a significant advance in the technology. The energy for the seismic waves on our rigs are created by pneumatic hammers incorporated into a steel beam in the jack system of the CPT rig. This creates a very powerful, repeatable energy source which is fast and easy to use.

  • Standard Piezocone Parameters (CPTU) – CPTU includes tip friction (Qt), sleeve friction (Fs), pore pressure (U2), and inclination (i) parameters.
  • Seismic Cone Parameters (SCPTU and SCPT) – Our SCPTU cone includes the standard piezocone parameters described above and adds shear wave (S1 and S2 waves), and compression wave (P-wave) readings.
  • Specialty Cone Parameters – Our current specialty cone is a Conductivity Cone (CCPTU), this cone includes the standard CPTU parameters and adds conductivity/resistivity readings. This cone is especially useful for environmental investigations due to its ability to indirectly differentiate between the soil types of water-bearing strata (for example organic content in clay), free-phase and dissolved phase contaminant plumes, salinity, total dissolved solids and other hydrogeologic conditions. Other cones and cone attachments are available by special arrangement.