Our self-contained unit is enclosed in an all weather van for year-round operation. It is mounted on an FL70, two-wheel drive, with four independent outriggers for leveling. A 200-gallon on board water tank is located in rear bumper. The total weight of the equipment is approximately 26,000 lbs. and may be loaded to approximately 30,000 lbs. The probe is located as near the center of gravity as possible to take advantage of the existing reaction force.
Typical probe depths normally range from 25 to 180 feet with some probes extending to 230 feet plus. Probe depths are often limited by the inherent of the cone itself, or the imposed load restriction due to repeated heavy stressing of rods. We feel that the Dutch Cone Penetrometer we are currently using strikes a good balance between the down pressure and overall cone and rod capacity.
Subsurface Technologies utilizes the Hogentogler Seismic/Pore Pressure 10 ton Subtraction Electronic Cone Penetrometer. The 10 sq. cm. sixty degree cone with the 150 sq. cm. sleeve conforms to all international standards. We also utilize the Enhanced Field Computer System (EFCS) for acquisition and presentation of data.
The cone is normally advanced at a rate of 2cm/sec. (ASTM standards). Rates can or may be reduced or stopped for short durations to monitor pore pressure effects or while taking shear wave velocities. Shear wave velocities are taken by stopping the probe at designated intervals to record data. Most Dutch Cone units utilize a friction reducer located approximately 24 inches above the cone. The reducer enlarges the hole, thus reducing drag on the rods. Attempting to obtain data while pulling rods would result in a void area between the cone and the soil.
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