Haga Click aquí para instalar
In TRX-NeXT a considerable expertise in design, implementation and interpretation of geophysical surveys has been developed through the years. This professional skill, associated with dedicated work, high quality standards and client oriented service represents our "Core Business" and recognized specialty.
The wide variety of equipment and available techniques enables TRX professionals to face each project with the appropriate methodology, instrumentation and industrial scale approach. This capability and experience has been fully integrated with multidisciplinary interpretation methods allowing effective and practical solutions to various geo scientific problems.
" … When you can measure what you are talking about and express it in numbers, you know something about it." Lord Kelvin 1883.
Integration of geophysical and multidisciplinary methods in:
TRX is a recognized leading geo-scientific consultancy group in Noninvasive - Nondestructive techniques application and studies in URBAN and INDUSTRIAL environments.
This technique consists in measuring relative changes in the earth gravity field. Variations, also subtle of the subsurface materials density produce anomalies in the gravity field that can be measured accurately.
TRX-NeXT group uses a high resolution digital micro gravimeter Scintrex CG-5 model and state of the art software.
The application of this method allows obtaining information related to subsoil/rock magnetic properties. In practice it measures the effect on the relative content and distribution of magnetite and magnetic minerals in the subsurface allowing characterizing geological environments and identifying magnetic objects.
TRX-NeXT group uses four (4) high-resolution digital GEM GSM-19 Overhauser magnetometers, in gradiometer, walking mag configurations with omni directional sensors for low latitude investigations and GPS synchronized positioning.
The method allows to measure, in certain energy windows associated to unstable isotopes, relative concentrations of radioactive elements associated to minerals present in rocks, soils within the first dozens of meters of depth
TRX-NeXT group uses an Exploranium GR-256 and an RS125 Radiation Solutions spectrometer.
In electrical methods, a current I is transmitted into the ground with two electrodes (A, B), while the difference of potential V produced by the circulation of this current into the geological layers is measured with two other electrodes (M, N). This allows investigating the resistivity parameter distribution in the subsurface. As a function of the field configuration, soundings (VES) or multi electrode arrays, i.e. electrical tomography (ERT Electric Resistivity Tomography), can be acquired. Investigation depths of electrical methods are directly related with data acquisition array geometry and depends on the resistivity of the investigated medium.
The purpose of a VES is determining the vertical distribution of subsoil layer resistivities beneath the investigated point. TRX group commonly uses the "Schlumberger symmetric quadripole." This application, despite its relative complex execution logistics is considered a valid and robust tool for small-scale budget studies. The investigation depth of this method is in the order of 0.1-0.3 times the total length of the arrangement AB used. For this, lots of space is needed for the array in order to characterize deep targets (for a desired investigation depth of 200 m an arrangement of AB/2 = 1000m is needed along with at least 500W transmitter power!!!!).
ERT is a geophysical imaging technology that measures electrical resistivity in soil and rock using an array of electrodes and automated measurements from the ground surface. This application is the modern definition of a classic electric profiling system that takes advantage of technological innovations both in the acquisition (with computerized multichannel instruments) as well as in processing and quantitative 2D /3D interpretation. For Schlumberger, Wenner and Dipole-Dipole configurations the investigation depth of the method is in the order of 0.2 times the total length of the array).
TRX-NeXT group uses different units.
The induced polarization method quantifies the capacitive properties of geological formations or elements, minerals, fluids present in the subsurface that act as "mini-capacitors." These capacitive features could be clays, anomalous minerals as disseminated sulphides, while fluids might be represented by heavy metals pollution.
TRX-NeXT group uses the following instrumentation:
Seismic methods are the most commonly conducted geophysical surveys for engineering investigations. They provide engineers and geologists with the most basic of geologic data via simple procedures with common equipment. Any mechanical vibration is initiated by a source and travels to the location where the vibration is recorded. These vibrations are seismic waves, which include compressional and shear waves, that are measured by seismographs. The Seismic reflection technique maps the subsurface stratigraphy based on density and velocity contrasts between earth materials. The seismic wave, generated at the ground surface, travels through the earth and is reflected an interfaces where a change in density and velocity occurs. The reflected waves are detected by a geophone array and recorded by a seismograph. The Seismic refraction method uses seismic waves, introduced into the ground by a hammer/weight-drop source, to define the compressional velocity of the subsoil. The seismic wave changes direction and speed, being refracted, as it propagates through the earth. When the refracted seismic wave reaches an interface at a critical incident angle, the energy travels along the interface and rebound seismic wavelets back to surface. Geophones placed at selected intervals along the ground surface detect the ground motion and send an electrical signal, via a cable, to the seismograph. The seismograph digitizes, amplifies, filters and records the incoming signals. Analysis of the arrival times of the refracted wave provides a means for calculating the seismic velocity and modeling depths to subsurface layers.
TRX NeXT group offers a full range of micro tremors and surface waves methods, modern techniques used for in situ measurements of shear wave velocity (Vs) profiles using ambient noise. Among these seismic methods TRX is specialized in the application of ReMi (refraction micro tremors), MASW (Multichannel Array of Surface Waves), SPAC, FK, etc.
TRX is pioneer in the ReMi method application and is the official representative in Latin America with exclusivity in Venezuela, Colombia, Ecuador and Chile.
The main advantages of these methods are:
Para la adquisición y procesamiento/interpretación de datos TRX usa una unidad digital de alta resolución modelo DAQ-Link III de 48 canales, geófonos de 1, 4.5, 10 Hz y de banda ancha (1-315 Hz) ecualizados electrónicamente y software de última generación.
Seismic methods, further to providing information about subsurface geometry, allow derivating geotechnical parameters directly related to the geomechanical and dynamics properties of the investigated formations.
TRX Group is specialized in the application of different seismic methods in shallow investigations applied in geotechnical and engineering projects.
Among the methods used:
TRX-NeXT group uses high-resolution digital, 24 and 48 channels, DAQ-Link III seismographs and multiple 32 bit 3-channel wireless iSeis Sigma units with 4.5, 10, 14 Hz and broadband (1-315 Hz) electronically equalized Geophones
Vibration monitoring represents the response analysis of sites, sensitive areas or structures to ground / foundations motion, generally produced by industrial activities or natural movements. This assessment evaluates the dynamic characteristics of the investigated site and quantifies the possible involvement of events represented by repetitive or temporary movements to structures or humans.
TRX - NeXT group uses a 6 channel digital unit Syscom 3000 CE-2012 model, a triaxial high resolution MS 2006+ geophone and latest generation software
TRX Group offers a wide experience in acquisition and advanced processing / modeling of Electromagnetic (EM) methods. The availability of a broad range of modern equipment and software, allows the maximum use of information supplied by these technologies.
EM methods allow to measure subsurface conductivity (reciprocal of resistivity) variations. The ground electrical conductivity depends on different parameters of soil and geology of the site as:
The main advantage of EM methods over traditional applications of resistivity is not sensitive to noise associated with surface geological features such as laterite, weathering, etc., and inappropriate contact of the electrodes with the ground.
Conceptually, there are two major categories of electromagnetic methods, those working in the Frequency Domain (FDEM) and those working in the Time Domain (TDEM). A “third” method is the VLF - VLF / R EM, which could be grouped among the frequency domain ones.
The frequency domain method is a technique that uses the inductive properties of a continuous primary electromagnetic field to measure the conductivity of the material through which the field passes. Because the material of which the subsurface is composed controls the ability of the subsurface to carry an electrical current (or hold a secondary field), the conductivity of a material correlates well with grain size (and generally increases with decreasing grain size) these methods can be used to both identify lateral boundaries between different materials and lithology of the materials. Frequency domain methods are also highly sensitive to the chemistry of materials, and therefore can be used for many groundwater applications such as the delineation of shallow high-TDS and contaminant plumes (DNAPL and LNAPL) and the delineation of weathered, altered, or vertical water-bearing zones in bedrock. In addition, these methods are very sensitive to metallic material, and can be used to detect metallic pipes, USTs and drums. The main advantages of this method are given by the speed of execution, reduced costs and not requiring contact with the ground. Innovations in quantitative processing techniques present the method as an important tool in engineering, geotechnical and environmental applications.
The time domain method is a technique that uses the inductive properties of a transient primary electromagnetic field to measure the ground response or resistivity of the material through which the field passes after the primary field is turned off.
It is a method whose results, in terms of possibility to characterize the electro stratigraphic sequence, are comparable to those of electrical methods with the clear advantage of greater speed of execution, not requiring contact with the soil or large arrays and its economy of execution (as compared to the quantity and quality of data obtained). Innovations in quantitative processing techniques present the method as an important tool in engineering, geotechnical, hydrology and environmental applications.
The VLF method uses the signal of powerful remote radio transmitters set up in different parts of the world for military communications. In radio communications terminology, VLF means very low frequency, about 15 to 25 kHz. Relative to frequencies generally used in geophysical exploration, these are actually very high frequencies. The radiated field from a remote VLF transmitter, propagating over a uniform or horizontally layered earth and measured on the earth's surface, consists of a vertical electric field component and a horizontal magnetic field component each perpendicular to the direction of propagation. This allow characterizing variations in resistivity in the subsurface to a depth of several dozens of meters by the time electrical properties in the subsoil are affected from the interaction with low frequency radio waves
TRX - NeXT Group uses a Geonics EM-16 /16R unit.
The TRX group is specialized in radar applications both in the classic Ground Penetrating Radar (GPR) as in the Interferometric Radar version.
The TRX NeXT group offers a full range of options in GPR applications, the most versatile tool in no invasive, NO-DIG, trenchless investigations.
Ground penetrating radar (commonly called GPR) is a geophysical method that has been developed for shallow, high-resolution, subsurface investigations of the earth. GPR uses high frequency electromagnetic waves (generally 25 MHz to 2.0GHz) to acquire subsurface information. EM pulse energy is propagated downward into the ground and is partially reflected back to the surface from boundaries at which electrical property contrasts are found (the principle is similar to the one of seismic reflection). GPR is a method that is commonly used for civil engineering-geotechnical, geological, environmental, archaeological, and other shallow investigations (1-40m).
TRX group uses four (4) high resolution units with a broad range of shielded and unshielded antennas. 3 IDS GPR RIS K2 multichannel-multi frequency + 1 Mala Ramac GPR with a full range of shielded antennas (80, 200, 600 and 2000 MHz), dual frequency shielded antennas (2x200-600 MHz, 600-1600 MHz), a 4-channel multi polar dual frequency unit, plus surface unshielded antennas 25, 50, 100, 200, 400 and a borehole 300 MHz unit. This with latest generation software capable of a 3D CAD interpretation output.
Radar Interferometry is an innovative remote sensing technique that allows vibration and full-scale displacement monitoring of structures (bridges, dams, towers, buildings, etc..) and earth surfaces (instable slopes, landslides, volcanoes, glaciers, mining fronts etc.).
An interferometric radar is constituted by a high frequency (17-20 GHz) electromagnetic waves transmitter and receiver. The transmitted waves are reflected by the object of interest and measured by a high resolution receiver. There are two interferometer radar configurations for engineering applications:
For the acquisition and processing / interpretation of data the TRX group uses IDS IBIS S and L (M) units with the latest technology processing / interpretation software and direct support of the manufacturer experts.
TRX group, which operates in this specialty since 2004, offers the full range of tools for foundations / piles testing.
Piles and other structures belonging to foundations can be very important structural engineering elements (for dynamic loading and role) and very expensive construction elements. These conditions have led the need for high quality control to installation processes and monitoring of post-construction characteristics of the foundations elements. Rules and regulations of different countries define references and precise procedures for foundation testing.
There are two main fields of application of geophysical methods of testing foundations / piles, the integrity analysis and dynamic load tests and the characterization of the dimensions / lengths of the foundations.
Foundations Integrity Assessment & Dynamic Load Tests
The PIT method (Pile Integrity Testing), defined as Low Strain Dynamic testing, allows to detect defects, soil inclusions and pile necking, diameter increases (bulbing) as well as approximate pile lengths using a sonic pulse. It is applicable to the top of piles and surface structures accessible from the surface and where has not yet built the super structure above them. In the scope of this test the TRX group offers the combination of the Sonic Echo method, which requires a measurement of the travel time of seismic waves (time domain), and the Impulse Response method which uses spectral analysis (frequency domain) for interpretation. The equipment and software used by the TRX group comply with ASTM D5882-07 norm and many other regulations and specifications.
TRX group uses a unit of "pulse echo" - "transient response" (Pile Dynamics PIT-FV).
The borehole Sonic method may evaluate the quality of the concrete of deep foundations by the Single Hole Sonic Logging (SSL) method, in addition to performing Cross Hole Sonic Logging (CSL). Drilled shafts are prepared for the test by installation of PVC or steel tubes during their construction. During the test a transmitter is lowered down one of the tubes and sends a high frequency signal to a receiver inserted in another tube. Transmitter and receiver move down each pair of tubes, scanning the entire length of the shaft.
The equipment and software used by the TRX group meets or exceeds the specifications of ASTM D6760-08 - Standard Test Method for Integrity Testing of Concrete Deep Foundations by Ultrasonic crosshole Testing and many other codes and regulations.
The PDA method (Pile Dynamic Testing) is defined as High Strain Dynamic testing and allows evaluating piles integrity as well as its load capacity and dynamic response. The Pile Driving Analyzer (PDA) acquires data from accelerometers and strain transducers attached to the pile or shaft, while it is impacted by a pile driving hammer or other suitable drop weight. The PDA analyzer and software used by the TRX group comply with ASTM D4945 and many other codes and specifications.
The main objective of the Dynamic Testing is to obtain the breaking capacity of the soil. However, alongside other information can be obtained by the test. Some of the most important are:
For the acquisition and processing / interpretation of data TRX group uses a PDI high-resolution Pile Dynamics PAX 2011 unit and CAPWAP latest generation software.
Foundation / Piles Dimensions and Length Characterization
The methods described below can be additionally used by TRX group for determining the dimensions and/or length of foundations / piles. The surface methods allow the investigation of foundations / piles whose structures are accessible
The PIT method (Pile Integrity Testing), described above, allows to investigate the length of piles using a sonic pulse.
TRX group uses a unit of "pulse echo" - "transient response" (Pile Dynamics PIT-FV)
Through the use of different frequencies antennas (especially high frequency ones) GPR sections can show dimensions and integrity of foundations.
TRX group uses a multichannel acquisition unit IDS RIS K2 with mono statics antennas, bi static and cross-polar mono and bi frequencies of 2000, 600, 200 MHz with the possibility of “transillumination" between concrete surfaces.
Is a borehole method that is used for determining the depth and unknown geometry of an foundation or pile, using a sonic transmitter and receiver to obtain electromagnetic waves reflections along the structure surface.
TRX group uses a Pile Dynamics unit.
This method that is used for determining the depth and unknown geometry of an foundation or pile using a GPR antenna to obtain electromagnetic waves reflections along the structure surface.
TRX group uses an IDS RIS K2 GPR with a 300 MHz antenna probe.
The Parallel Seismic (PS) method is a borehole test method for determining depths of foundations. The method requires the installation of cased borehole close to the foundation being tested. The method can be used when the foundation tops are not accessible or when the piles are too long and slender (such as H piles or driven piles) to be testable by sonic echo techniques.
TRX group uses a high resolution DAQ LINQ III - 24 seismograph and two triaxial sensors (ultra-thin for small holes).
Induction Field (IF) method is used for the determination of the unknown depth of steel or continuously reinforced concrete piles. This is an electrical method that relies on detecting the magnetic field in response to an oscillating current impressed into a steel pile. In order for this method to work, the pile must, therefore, contain electrically conductive materials. For reinforced concrete piles, this usually implies that reinforcing rebar extends along its full length. A sensor is placed down a drillhole located close to the pile and detects the changing magnetic field strength. This sensor could be a magnetic field sensor or a coil. Along the length of the pile, the magnetic field strength will be relatively strong. However, the magnetic field strength will be significantly diminished at levels in the drillhole beneath the bottom of the pile to a residual conductivity value of the soil or bedrock. This change in the magnetic field strength is used to determine the depth of the pile.
TRX group uses a Mount Sopris unit
The TRX group offers a wide range of methods to log / testing well. Among these:
Single Point Resistance. Resistivity. Used in hydrology studies to determine the conductivity of formation water and boundaries of layers. Single point logs cannot be used for quantitative interpretation, but they are excellent for lithologic information. The resistance of any medium depends not only on its composition, but also on the cross sectional area and length of the path through that medium. Single point resistance systems measure the resistance, in W, between an electrode in the well and an electrode at the surface or between two electrodes in the well. It is applied in an uncased borehole.
Self Potential. Spontaneous potential. The spontaneous potential log is a record of potentials or voltages that develop at the contacts between shale or clay beds and a sand aquifer, where they are penetrated by a drill hole. This method is used in a timely manner to solve aquifers boundaries or water movement. It is applied in an uncased borehole.
Gamma spectrometry. It is the most important logging tool in hydrogeology. Provides information about the boundaries of layers, the clay content and, indirectly, permeability. It can be run in wells with PVC or iron pipes. Because of its sensitivity to clay minerals, one of the most common uses for this log is to delineate clays and shales; however, it is also very effective for the identification of potassium-bearing, uranium-bearing and thorium-bearing sediments and rocks under certain conditions. The natural gamma log is particularly useful where geologic layers of contrasting natural gamma radiation are juxtaposed, such as sand vs. clay, arkose vs. limestone, and granite vs. schist; and for mineral exploration. The natural gamma tool has no casing restrictions and is capable of measuring natural gamma radiation in the vadose zone. It is an essential tool (along with the TV camera) to the reevaluation of old wells design.
Water depletion, flooding, salinization, and a shortage of clean drinking water are problems that continue to grow worldwide. Regular and reliable measuring and monitoring of groundwater levels have become more important than ever. TRX uses and represent the products of Schlumberger Water Services SWS.
SWS sensors of can be applied to:
The TRX group offers both the Downhole as the Crosshole methods using mechanical high-energy sources which produce an excellent signal noise ratio indispensable to obtain good quality data.
The two methods can be applied to engineering and geotechnical studies:
The full wave sonic log allows determining the speed of both shear Vs and compressional Vp waves. Subsequently, elastic moduli, Poisson's ratio and parameters associated with rock quality can be assessed. This defines the method as fundamental tool in engineering/construction projects, mine design and in excavation technologies optimization (blasting or tunneling machine selection). Additionally, in open holes, allows estimating fracturation, porosity and permeability.
This tool is assuming an increasingly greater role in the hydrogeological, environmental, geotechnical and mining industry. Measurements can be made inside the same well or can be made between wells in a tomographic form (transmitter and receiver in separate wells). Measurements in a single well permit, in particular, the location and orientation of layering and fractures and a number of other parameters. Tomography can map the fracture zones between wells. This information is very important in the study of fractured limestone aquifers as well as in the study of contaminant transport. Some applications are:
The TV record allows inspection of well conditions, see the lithological texture, size and color of rock grains and evaluate the water level and characteristics inside the well. These records can be obtained in wells filled with water or air. The image can be displayed in real time and results represents the ideal method to study fractured rock aquifers and the physical condition of operational and disused well casings.