KTE provides a wide variety of Cone Penetration Testing (CPT) services. We operate two 30-ton CPT rigs manufactured by Vertek as well as several Geoprobe rigs and limited access rigs that are capable of performing CPT.
Each 30-ton rig uses 15 sq cm piezocones and are used on projects that are readily accessible. These rigs are climate controlled and have on board computers and printers for real time CPT data plotting and analyses (see example plot). Results can also be e-mailed to our client directly from the field. These rigs also have a built in seismic hammer in the front jack pad which is accuated by the operator inside the rig. This allows for efficient seismic shear wave measurements during a CPT sounding (see example shear wave traces). The CPT soundings are performed in accordance with ASTM D3441 methods.
Vertek data acquisition and plotting software is used for acquiring and plotting the CPT data in the field. CPT plots with a wide variety of parameters and color soil classification profiles are provided. In addition, we utilize CPTINT software developed by the University of British Columbia to provide averaged CPT data (generally over one foot intervals) and interpreted strength parameters (i.e. SPT N values, Undrained Shear Strength, Friction Angle, etc.). In addition to the data provided in the field, a summary report with a description of the work performed and a complete set of the CPT output is also forwarded to our clients. CPT data files are e-mailed to our clients for use in other commercially available evaluation software. The data is in a simple comma delineated format and can be easily changed to other formats when required.
CPT soundings with the Geoprobe rigs and limited access rigs are performed using a cordless CPT system manufactured by Geotech AB of Sweden. With this system we use 10 sq cm piezocones and do not need a cable from the piezocone to the data acquisition system. Instead the CPT data is transmitted through the push rods using a sound signal. The data from the sound signal is received by a microphone and sent to the data acquisition system and finally to the computer where CPT data is plotted in real time (see schematic of cordless CPT system).
This cordless system has the advantage of use with any of our Geoprobe rigs with augering capabilities (Geoprobe 6600) or our limited access rigs. The reaction to push the CPT soundings is provided by screw in anchors (4-10 inch sizes generally used) that are attached to the foot of the rig. For locations on concrete, four 3/4 inch concrete anchor bolts are used for reaction to hold down the foot of the rig. The “anchored down” rigs generally provide about 15 tons of reaction to push with. This is about half of the reaction from our full size rig. As a general rule the anchored down rigs cannot push through soils with tip resistance greater than 300-400 tsf.