Dilatometer Testing

Gregg deploys a seismic dilatometer (SDMT) made by Studio Marchetti in Italy. The probe is capable of conducting dilatometer and seismic testing down to 50m, or approx. 150ft in depth. The DMT equipment can be advanced with any of Gregg Drilling’s CPT push rigs or a standard drill rig. Static push is recommend compared to a driven or hammered method. The DMT pressures can be covered to a p and p reading which in turn can be used for numerous soil correlations including:

  • Constrained Modulus
  • Undrained Shear Strength
  • Earth Pressure Coefficient
  • Overconsolidation Ratio (OCR)
  • Friction Angle


The dilatometer blade is advanced into the ground using standard push equipment and rods. At the starting depth of the test, advancement is stopped and the operator inflates the membrane and takes two readings. This process takes approximately 1-minute.

A-pressure: the pressure required to just begin to move the membrane against the soil (lift-off)
B-pressure: the pressure required to move the center of membrane 1.1mm against the soil.

An optional C-reading or “closing pressure” may be taken by slowly deflating the membrane soon after B is reached. The blade is then advanced one depth increment (20cm) and the process is repeated.

Download the Dilatometer specification sheet for more details.