FIELD TESTING

Self-contained electronic quasi static cone penetration units (CPT) provide rapid in situ subsurface data acquisition. CPT provides measurements of cone tip resistance, local friction, inclination, dynamic pore pressure and temperature. CPT also assists with seismic shear wave studies using seismic cone geophones. Analysis of liquefaction potential is becoming an area of increasing importance for CPT.

Geotechnical field testing, in conjunction with exploration drilling programs, includes the "standard penetration" tests, impact hammer cone penetration-penetrometer pull-friction tests, in situ permeability tests (flow-meter pressure or draw-down), vane shear strength, dilatometer and preliminary field classification. Field testing services also include density testing and observation of engineered fill construction. Field densities are obtained by the nuclear and sand-cone (ASTM and CTM) methods and supplemented by the "drive cylinder" (ASTM) method.

A variety of earth materials sampling and testing devices are available to the drill exploration units including "standard penetration", piston-Shelby, California, Shelby, and ring-lined thin-wall and are used for recovery of environmental and "undisturbed" soil samples. The custom-made Taber Consultants 2.5" I.D. thin-wall sampler provides drive samples with a lower disturbance ratio than available from commercially-produced samplers. Core-barrels - diamond or carbide-tipped; with or without retractable Shelby liner (brass or stainless steel for environmental samples) - are used for sampling of rock and consolidated materials. The impact penetration hammer is also equipped with calibrated hydraulic jacks to measure withdrawal force as well as perform other field tests.

Equipment available in-house also includes signal enhanced seismic timing units. These compact geophysical testing instruments can often rapidly define and delineate materials distribution and excavation characteristics. Additional field testing capabilities include resistivity, pH and plate-bearing and pile-load tests (with a series of calibrated 100-ton capacity rams and auxiliary equipment).