Cones & Modules
Mechanical and electrical (both analogue and digital) CPT cones
Eijkelkamp GeoPoint SoilSolutions provides high-quality cones, both mechanical and electrical. The electrical cone contains temperature-compensated strain gauge transducers to measure the tip resistance and the sleeve friction. In case of a digital cone, built-in analogue to digital conversion (32-bit resolution) and built-in cone ID with calibration factors eliminates the effects of user and system errors on the measurements. The cones can be supplied as compression cones (with independent load cells for the tip resistance and the sleeve friction) or subtraction cones (a more robust design and therefore more durable).
Available options for the electrical cones include:
- Analogue cones, with or without built-in amplifier
- 32-bit digital cones (class 1+)
- Subtraction and compression type (class 1)
- Pore water pressure in u1, u2 or u3 position
- 1, 2, 5, 10 or 15 cm2 cross-sectional area
- 10 to 200 kN max load
- Ball- or T-bar cone
Expandable with modules to measure and capture:
- Temperature
- Magnetic field
- Video
- Fluorescence
- Electrical conductivity
- Thermal conductivity
- Seismic waves
- Water content/dielectric constant
Other than the seismic module, which can be combined with all electrical cone types, the modules must be used in combination with a 15 cm2 cone or be applied on a stand-alone basis with a dummy tip.
Electrical SonicCPT cone
When a cone cannot be pushed any deeper due to the encountered friction, it may be possible to reduce the friction along the CPT rods by applying some vibration. While a standard electrical CPT cone may not be able to withstand such action, the SonicCPT cone can. Any electrical subtraction cone without pore water pressure measurement can be supplied as a SonicCPT cone.
Seismic module
Seismic cone penetration testing has demonstrated to be a very accurate and reliable method to determine low strain in situ compression (P) and shear (S) wave velocity profiles. These velocities are directly related to the various soil elastic constants (such as the Poisson’s ratio, shear modulus, bulk modulus and Young’s modulus) and they are used in both static and dynamic soil analysis (to assess the response to earthquakes or dynamic loads produced by wind turbines or rotating equipment). Another important use of estimated shear wave velocities in geotechnical design is in the liquefaction assessment of soils (since the shear wave velocity is influenced by many of the same variables that influence liquefaction).
The following options are available for this module:
- use of either geophones or accelerometers as seismic sensor
- use of either single or dual array of seismic sensors
Magnetometer module
A magnetometer is a scientific instrument used to measure the strength and/or direction of the magnetic field. A mass of ferromagnetic material creates though a detectable disturbance in this magnetic field. This magnetic anomaly produces a weak alternating magnetic field that is picked up by the magnetometer.
The magnetometer module can detect objects within a radius of approx. 2 m and is very suitable for:
- Unexploded bomb/ordnance surveys
- Determination of the length of foundation/sheet piles
- Determination of the position of retaining or tieback anchors
- Determination of the position of power cables
Conductivity module
The dielectrical parameters of the soil, the electrical conductivity and the electrical permittivity vary predominantly with the soil’s water content and the contamination with hydrocarbons. Furthermore, electrical conductivity is inversely proportional to particle size (e.g., clays usually have higher conductivity than sands). The conductivity is measured between two insulated electrodes, using the soil mass as dielectric correlated material.
Video module
The video module records images that show soil texture, colour, grain size and other features of the soil passing the miniature colour camera. When using an ultraviolet (UV) light source the module can also indicate the presence of hydrocarbon compounds (as they generally fluoresce when excited by UV light). The material obtained can be represented as a boring log, which can be viewed together with the CPT data that were obtained as the video module was pushed into the soil on the back of an electrical CPT cone.
Gamma-ray (spectrometer) module
The technique of measuring the natural radiation in the earth’s surface is called “radiometry”. During a radiometric survey the gamma radiation emitted by the surrounding soil is measured, either simply by recording the intensity of the gamma radiation (“counts”) or by determining the spectrum of the intensity. The latter will allow quantification of the various naturally radioactive elements, such as potassium (K), uranium (U) and thorium (Th). The outcome can then be used for soil classifications as every type of soil and mineral has its own so-called fingerprint of these three elements.
