Cone Penetration Testing (CPT) is the most versatile device for real time in situ soil testing, for characterizing the subsurface without disturbing the ground around it. CPT provides detailed information on subsurface soil type and density and geotechnical parameters.

CPT consists of a steel cone that is hydraulically pushed into the ground and sensors at the tip and sleeve of the cone collect data at a continuous rate. The friction sleeve around the steel cone collects resistance and the tip qualifies the strength of the soil.

Each CPT investigation with GPS will receive data for interpretation of soil behavior type based on Robertson 1986 Classification Method and graphic display of soil type, cone tip resistance, sleeve friction resistance, and pore pressure at u2 position.

Data includes tabulated of depth, soil type, tip resistance, estimated unit weight, effective overburden stress, constrained modulus in normally consolidated sands, constrained modulus in fine-grained soils, sleeve friction, effective friction angle in sands, normalized cone resistance and friction ratio, range of relative density, and calculated N60 values.  Other soil properties that can be estimate with some assumptions include undrained shear strength of normally consolidated marine clays, overconsolidation ratio, and soil permeability.  The tabulated data has standard increments of 0.25 feet with the values representing the arithmetic mean of the interval.

GPS takes the tooling of the CPT and combined with a limited access rig that can fit through a standard 36" opening to provide the optimal way of collecting shallow soil data.
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