fugro cpt geotech

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CPT Geotechnical Services

Fugro has pioneered the development of Cone Penetration Technology (CPT) for both geotechnical and environmental studies. The conventional approach to such studies usually involves drilling for soil and groundwater samples. Samples are then taken to a laboratory for testing and engineering analysis. Over the years, CPT has become a preferred method for conducting site investigations of subsurface conditions. The speed and data quality of CPT systems surpass conventional methods of field data acquisition. Technology now exists to measure soil properties including subsurface contamination. In addition, typical information obtained by CPT testing includes tip resistance, sleeve resistance, pore pressure, resistivity and dynamic soil properties.

How does the CPT system work? A cylindrical steel cone is pushed hydraulically into the soil (to depths in excess of 200 feet) to identify soil types and groundwater migration pathways. Because it is “pushed,” it does not produce drill fluids or drill cuttings. With conventional drilling methods, disposal of drill cuttings and fluids often poses significant hazardous waste problems. Through the use of electronic strain gauges that measure physical soil properties, the acquired data produces a continuous, real-time stratigraphic record (or “sounding”). Five minutes after the sounding is complete, the computer produces a printout of the data complete with a stratigraphic column.

A 30-foot sounding can be completed in thirty minutes or less compared to several hours with conventional drilling and continuous sampling. The precision of the Fugro instruments eliminates much of the subjectiveness of conventional soil logging, giving the geotechnical engineers / hydrogeologists immediate information for a realistic look at subsurface conditions. Further, the study can be tailored in the field to identify geological trends and optimal locations for groundwater samples or monitor wells.

CPT advanTagesGeotechnical and environmental site investigationsContinuous soil stratigraphyIdentification of thin seams and layersEstimation of geotechnical and hydrogeological propertiesPrompt collection and interpretation of field data (2 to 3 times faster than traditional methods) Economical (typically ⅓ the price of borings)Elimination of drill cuttings; site remains undisturbedEnvironmentally friendlyEnhanced operational safetyInclement weather operabilityTerrain adaptability (land, marsh and open water)

Local Expertise. Worldwide Strength.Fugro Consultants, Inc. is an engineering and consulting firm that provides site exploration, geotechnical engineering, advanced soils testing, construction quality testing, nondestructive testing, engineering geophysics, pavement design and management, roofing, and specialty testing. We are part of the multi-disciplined, publicly traded Fugro Group of companies with over 10,500 employees in 275 offices operating in 50 countries. (888) 241-6615 www.fugroconsultants.com

TyPes of Cone ProbesThe Piezo/Conductivity Cone Penetrometer records the dynamic pore pressure while simultaneously measuring the cone point resistance, sleeve friction, and electrical conductivity continuously during penetration.

The Push-In Groundwater Sampler is a surface-activated sampler that allows a sample to be obtained at a discrete depth with a teflon or stainless steel bailer.

The Push-In-Soil Sampler can be used to obtain a 1.5 in. diameter soil sample with a length up to 18 inches.

The Push-In Piezometer (monitor well) can be permanently installed with PVC casing to collect data on depth to groundwater, hydraulic gradients, thickness of free product, and groundwater flow direction.

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Cone Tip

Conical Tip

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PVCRiser

PVCScreen

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ConclusionExcellent tool for site investigations (speed of data collection, reliability and repeatability)Close correlation between tip resistance and soil shear strengthContinuous record of soil stratigraphy and soil properties Helpful guide in selecting samples for laboratory testing and QA/QC testingEffective interpolation of conditions between soil borings (e.g., CPT every 1000 ft.; soil borings every 3,000 ft.)

Fast and economicalUseful instrument for identifying sensitive areas including weak levees, bridge scour, and subsurface contamination Complementary tool for construction QA/QC (e.g., levees, bridges, facility expansion)

soil ParameTers Using CPT TeChnologySoil ClassificationUndrained Shear Strength, Cu

Standard Penetration Resistance, (N)Friction Angle, ØIn-Situ Relative Density, Dr

In-Situ Permeability, kConstrained Modulus, M Young’s Modulus, EDynamic Shear Modulus, G0

fugro cpt geotech

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