The techniques instrumentation, software and methodologies developed by gtom are used to underpin studies in waste management, contaminated land remediation, the protection of groundwater and soils, as well as the detection and mitigation of. Comparisons have been made between the tomograms and the geological cross sections in order to assess the technique under in situ conditions. The conventional approach involves lowering a 3component borehole geophone down one hole while lowering a source down an adjacent holes, firing the source at some prescribed depth interval. However, where it can be time consuming for the engineer is in translating multiple plots into a 3d assessment of anomalies. Ultrasonic cross hole testing of deep foundations 3d imaging. The software analyzes wave speeds derived from arrival time data from the scans of all pairs of tubes to yield a wave speed map of the entire shaft volume. Some of the key uses for industrial ct scanning have been. A ray tracing approach to restoration and resolution. Public roads peering into the unknown, mayjun 2009 fhwa. Experienced user of geophysical and general business software including microsoft office, adobe acrobat, autocad 2007, surf seis, geosoft oasis montaj. It is showed that pfm is a very effective tool in crosshole tomography signal processing, and is prospective for utilization in other realms of engineering. A technique for measuring a signal that is broadcast from a transmitter or source located in one well, to a receiver array placed in a neighboring well. The geophysical tomography gtom team provides leadingedge technology for noninvasive geoelectrical imaging of the shallow subsurface.
As a project partner, volume graphics brings expertise in quality assurance and process optimization to the team via its advanced industrial computed tomography ct dataanalysis software. Crosshole tomography ct is an imaging method analogous to catscanning in the medical industry and uses acoustic waves. Sensitivity analysis of cross hole electrode arrays. Qualitative and quantitative analysis of certain electrode arrays. Our tomographic data interpretation is based on physically meaningful modeling of wave propagation with wave paths instead of conventional seismic rays. The crosshole sonic logging method is normally applied as a quality assurance qa technique for newly placed drilled shafts and auger cast piles, but can also be applied. Application of crosshole tomography for assessment of. Drilled shafts guidelines wv department of transportation. Founded more than 24 years ago we specialize in developing pile testing systems for quality control and integrity testing of deep foundations piles, shafts, caissons and barrettes read more. This software package includes crosshole survey design, model building and modeling, data preprocessing, cdp transformation, tomography, waveequation. Pditomo is software developed to supplement champ output from csl tests. As part of continuing research aimed at the detection of subsurface tunnels and voids, the u. Application of crosshole tomography for assessment of soil stabilization by grout injection. The crosshole sonic logging method is normally applied as a quality assurance qa technique for newly placed drilled shafts and auger cast piles, but can also be applied to slurry walls, mat foundations, and mass concrete pours.
Crosshole ultrasonic tomography and its application to karst. The chum cross hole ultra sonic monitor uses the crosshole sonic logging csl method to perform highresolution quality control of deep foundations the system uses an ultra sonic wave sent from a transmitter to a receiver pulled through water filled access tubes embedded in the concrete. Detection and mapping of fractures and cavities using. Crosshole sonic logging csl is a method to verify the structural integrity of drilled shafts and other concrete piles the csl method is considered to be more accurate than sonic echo testing in the determination of structural soundness of concrete within the drilled shaft inside of the rebar cage. The 3d ct wizard facility allows users to quickly set up and scan a component to obtain 3d ct data. The procedure involves solving a system of equations based on first arrival times fat in order to calculate wave speeds at various points within the shaft. Defects must be addressed if they affect two or more of the tested tube pairs at the same depth. Geological survey at a surface gold mine in the black hills mining district of south dakota. The techniques instrumentation, software and methodologies developed by gtom are used to underpin studies in waste management, contaminated land remediation, the protection of groundwater and soils, as well as the detection and mitigation of natural hazards. Using these measurements, calculations can then be made of the dynamic soil and rock properties for earthquake design analyses for structures per the usb, liquefaction potential studies, site. Causes and impacts in drilled shafts fhwacfltd08009, identifies conditions that affect the loadbearing capacity of drilled shafts by modeling various conditions and analyzing them with numerical methods. Bureau of mines recently completed a cooperative study with the u. It is possible to implement the deviation of the boreholes. Electrical resistivity tomography ert with downhole electrodessinglehole ert shert or crosshole ert chertis widely used in engineering projects.
Crosshole resistivity tomography crt crosshole resistivity tomography crt figure 1. Using this data, one can proceed to the spatial distribution of such parameters as the. The first one is the classical refraction tomography with both shots and receivers at the ground surface. Pditomo pile dynamics has released the new pditomo software for analysis of crosshole sonic logging csl data. Tomography is a mathematical procedure that is applied to crosshole sonic logging csl data, providing the user with a visual image of a shafts internal defects.
These include the ground probe radar gpr, microgravity, the multielectrode resistivity method, the crosshole radio wave tomography, the transient electromagnetic method tem and. Borehole seismic methods largely fall into two categories, namely, crosshole seismics and seismic tomography. A ray tracing approach to restoration and resolution enhancement in experimental ultrasound tomography. Crosshole seismic tomography cst works carried out between specified boreholes. Crosshole seismic cs and downhole seismic ds tests are performed on soil and rock sites to measure the inplace shear and compression wave velocity profiles of the soil and rock versus depth. Various geophysical methods have also been trialed on site to detect underground workings. The aim of 3d imaging for ultrasonic cross hole testing data is to produce a geometrical visual presentation showing the location of any anomalies and defects in concrete detected in the pile. The signal energy or attenuation can also be used in tomography. Geophysics at the borehole and crossborehole scale carole johnson, john lane. Crosshole or crosswell seismic measures the velocity of seismic waves between boreholes. Software geotomcg was used to carry out the sirt traveltime inversion see. Processed csl results from chaw tomography results of anomalous zones from pditomo.
Pile dynamics has released the new pditomo software for analysis of crosshole sonic logging csl data. Highlights laboratory study of cross hole ert in wellknown and controlled conditions. Maswremi surface waves data processing and interpretation, 2. It analyzes wave speeds derived from arrival time data from the scans of all pairs of tubes to yield a wave speed map of the entire shaft volume. Crosshole ultrasonic tomography is referred to ray tracing by griding method and image reconstruction by combining the successively linearized iteration with damping leastsquares qr decomposition, with which the result has better precision than that with crosshole seismic tomography by using the same inversion method in engineering geological investigation.
Seismic methods can provide detailed information about rock properties and geological structure between boreholes. It is shown that while the geological sections do not contain velocity information they have provided structural constraints which provided. Many tomographic interpretations of crosshole seismic traveltimes have approximated the raypaths with straight lines connecting the source and receiver. Borehole radar can be used in a single hole reflec tion mode or in a cross hole tomography mode. High resolution crosshole 2d seismic tomography youtube. Demonstration of joint inversion velocity and anisotropy parameter for 3 boreholes and surface data in zondst2d. Interwell seismic tomography for solving engineering geological. Crosshole sonic logging and velocity tomography imaging of. Crosshole seismic tomography and borehole logging for. This technique is used to create a display of formation properties such as acoustic velocity and attenuation, seismic reflectivity, or electromagnetic resistivity in the area between wells. Application of pattern filtering method in crosshole. Cross hole sonic logging and frequency tomography analysis of drilled shaft foundations to better evaluate anomalies locations april 2014 doi.
For a pile with 4 testing tubes there are 6 vertical profiles of first arrival time of ultrasonic impulse. Using these measurements, calculations can then be made of the dynamic soil and rock properties for earthquake design analyses for structures per the usb, liquefaction potential studies. There are many types of tomography, and i work with one called electron tomography. The use of crosshole tomography to evaluate drilled shaft repairs les r.
Crosshole tomography analyses can be done to better characterize the shape of an anomaly identified in crosshol e sonic logging between a tested tube pair. The grl engineer prepares a final report summarizing the csl test details, csl test results, tomography analysis if performed and recommendations. X86 version of diinso is totally free and can be use in scientific purposes, but it also has not any guarantees, so use diinso at your own. Sales, rentals of seismic sources, receivers and processing software, training and support. When combined with an swave survey, the data can additionally be used to provide information on material stiffness properties see crosshole seismic surveys. The mapping results can be displayed with 3d modeling software. Geophysical tomography engineering geology our research. The most popular in engineering geophysics was crosshole seismotomography. May 20, 2016 pile dynamics has released the new pditomo software for analysis of crosshole sonic logging csl data. The engineer repeats the test for each pair of tubes. The information obtained from crossborehole tomography, when properly interpreted in the context of all available information, can often be invaluable for preparing accurate geological cross sections for reservoir development and planning. The flh study, velocity variations in cross hole sonic logging surveys. A powerful pattern filtering software has been developed by delphi tool, and batch signals can be more efficiently processed.
A tomogram is a series of 2d images, called slices which stack together to form a 3d image. Crosshole seismic surveys are well established for noninvasive investigations of geological structure and are well suited for detecting hazards beneath buildings. Crosshole sonic logging evaluates the integrity of the concrete of drilled shafts and other bored or. Industrial computed tomography ct scanning is any computeraided tomographic process, usually xray computed tomography, that uses irradiation to produce threedimensional internal and external representations of a scanned object. The conventional approach involves lowering a 3component borehole geophone down one hole while lowering a source down an adjacent hole s, firing the source at some prescribed depth interval. New tomography software for cross hole sonic logging. Cross hole sonic logging foundation test group consulting. Crosshole seismic tomography outline borehole seismic tomography involves the measurement of the travel times of seismic ray paths between two or more boreholes in order to derive an image of seismic velocity in the intervening ground.
New astm standard for inclination piletest is the technical contact. The tools used for crosshole seismic tomography are basic borehole source power supply bbsps, pwave source sbs42 and hydrophone string type bhc4 by geotomographie. The geotechnical engineering circular number 10 of the usa federal highway administration states that tomography provides enhanced evaluation of potential defects and is among techniques that, while requiring specialized expertise for data interpretation, may be warranted for large structures. Crosshole seismic tomography which involves measuring travel times of seismic ray paths between two or more boreholes in order to derive an image of seismic velocities between the wells offers an. The results of crosshole seismic tomography at sites where there is good geological control are presented. Such an approach is now used in a lot of software implementing methods of seismic tomography. Refraction waves forward modeling and inversion in arbitrary layered medium, 3. The grl engineer uses the cross hole analyzer system champq to lower the probes to the bottom of the shaft and moves both the transmitter and receiver upward in unison, until the entire shaft length is scanned. We propose a cross hole imaging approach based on seismoelectric conversions sc associated with the transmission of seismic waves from seismic sources located in a borehole to receivers. Effective area is the percentage of crosssectional area with wave speeds greater than the effective wave speed ews selected by the user by the user, 3194 ms processed csl results from chaw tomography results of anomalous zones from pditomo. The primary application of borehole seismic tomography is in engineering studies for the identification of features such as fault zones and voids.
Since concrete strength is related to wave speed, this analysis is useful in cases. The program replaces an older tomography program, with significant advantages. Crosshole sonic logging csl is the most accurate and reliable technique for assessing the integrity of deep foundation elements constructed onsite from concrete or grout. There are many programs designed to view tomograms, and i have listed some of the more popular choices below particularly programs which can segment and visualize. Forward modelling in crosshole seismic tomography using. Swave borehole tomography a tool for geotechnica l site. Zondst2d is designed for twodimensional interpretation of seismic tomography data on refracted and reflected waves land, crossborehole and water variants. Crossborehole tomography can be thought of as an extension of sonic logging to the reservoir cross section between two boreholes.
Seismic data processing software geotomographie gmbh. For additional information on crosshole sonic logging csl and 3d tomography or. First, the crosshole seismic tomography method eliminates. X86 version of diinso is totally free and can be use in scientific purposes, but it also has not any guarantees, so use diinso at your own risk. Pdf application of crosshole seismic tomography in. Although the ability of engineers and facility managers to detect such corrosioncausing voids during construction is possible using a new frequency tomography analysis method developed by hajali. Tomographic analysis uses the cross hole sonic logging csl first arrival time fat data that is converted to velocity based on the distance between the transducers. Sis offers inhouse 2d and 3d computed tomography software. Ultrasonic cross hole testing of deep foundations 3d imaging yury volkovoy and richard stain sonic coring or more properly ultra sonic cross hole logging is a common test for concrete foundations and has been since the late 1960s. In the reflection mode, radar provides an image of discontinuities in the bedrock surrounding a borehole, including bedding planes, lithologic contacts, fractures, and cavities. Electrical resistivity tomography ert is a popular geophysical subsurfaceimaging technique and widely applied to mineral prospecting, hydrological exploration, environmental investigation and civil engineering, as well as archaeological mapping. Zhonglin was the first full time data scientist we brought on to help first. Laboratory study of the crosshole resistivity tomography.
Seismic tomography, crosshole, downhole geotomographie gmbh. Application of seismic tomography and geotechnical. Swave borehole tomography a tool for geotechnica l site characterization thomas fechner,geotomographie gmbh, neuwied, germany. Ahsin farid geophysicist fugro middle east linkedin. This section contains examples for setting up and running an cross hole tomographic inversion using sippi using the reference data from arren. In the built environment engineered surfaces or infrastructure e. Digisens 3d tomography software solutions for industry and. Borehole logging and crosshole seismic tomography investigation of unconsolidated soil materials in sikeston, mo, helped in defining the engineering properties of the investigated earth material interposed between two boreholes for a depth of 39 m below the surface. Deep tunnel detection using crosshole radar tomography. Seismic tomography is a technique for imaging the subsurface of the earth with seismic waves produced by earthquakes or explosions. Rayfractr geophysical software for geotechnical engineering and exploration generates subsurface velocity models from seismic first break data.
Tomography tomograph y provides a high resolution 2d or 3d volumetric image between two boreholes can image the entire length of the borehole no diminishing returns with depth tomography is data intensive specialized 3d software is required for true 3d imaging artifacts c an be present due to limited ray coverage near image boundaries. Crosshole seismic measurements for detection of disturbed. Ultrasound tomography startup star star star star star. More than two years experience of onshore geological environments and engineering relates geophysical projects at sites throughout the uae and qatar. Pditomo is a 3d tomography imaging tool that supplements the champ output. The analysis first identifies design criteria and construction. Ct testing is often performed after the csl testing has been performed to obtain more information about the size, shape, location, and severity of a suspected defect in a shaft. The use of crosshole tomography to evaluate drilled shaft repairs. Crosshole seismic tomography geophysics geoscienceworld. The software is used to process seismic crosshole testing data obtained after astm4428 and to output results. The hydrophone string has 24 channels with 1 m spacing. Now however testconsult has developed a new way of presenting results, using crosshole tomography techniques to produce both 2d and 3d images of the pile shaft. It predicts driving stresses, hammer performance, the relation between pile bearing capacity and net set per blow and the total driving time. Cross hole seismic tomography outline borehole seismic tomography involves the measurement of the travel times of seismic ray paths between two or more boreholes in order to derive an image of seismic velocity in the intervening ground.
Seismic data can be sorted and edited and traveltimes can be determined. Inversion of the seismic data confirms the value of tomographic imaging as a means of expressing the results in a form that is of practical value to the engineer. Cross borehole tomography can be thought of as an extension of sonic logging to the reservoir cross section between two boreholes. We use the windowsbased tomo1 software and slicerdicer software for users of an olson instruments crosshole sonic logging system. Timelapse crosshole electrical resistivity tomography. At a minimum, addressing flaws and defects must include recording offset csl measurements between all tube pair combinations where a flaw or defect was identified, as well as cross hole tomography ct using all offset data. Our reconstruction processing engine is optimized for multicore processors, efficient memory access and low cost graphics processing card. This method provides little indication of concrete soundness outside the cage. Rayfract seismic refraction and borehole tomography software provides subsurface seismic velocity models for geotechnical engineering and exploration.
A new technology for oil field characterization article pdf available in geophysics 143 january 1995 with 171 reads how we measure reads. This direction is used for detailed studies of rocks velocity structure in the. Model stacking technique to improve the quality of resistivity models. Pdf crosshole sonic logging and frequency tomography. Industrial ct scanning has been used in many areas of industry for internal inspection of components. Solutions for borehole and nearsurface seismic surveys. The geophysical tomography team crosshole resistivity.
In crosshole seismic tomography, however, these datapicking errors may not be treated as random variables with a gaussian distribution and the solution may often be biased. Computed tomography ct dataanalysis software cutting. Grl operates the largest dynamic pile testing firm in the world, as well as an industry leading provider of integrity test methods for deep foundations including thermal integrity profiling, crosshole sonic logging, and low strain integrity testing. Figure 1a is a sample shot gather on which the first arrivals of the far offset traces cannot be clearly identified and thus the picked times are not reliable at all. Crosshole sonic logging evaluates the integrity of the concrete of drilled shafts and other bored or castinplace deep foundations. The use of crosshole tomography to evaluate drilled shaft. Directinverse solver diinso is an electrical resistivity tomography ert software which orient to solve 3d direct and 2d3d inverse problems on direct current dc. We accompany manufacturers in designing and dimensioning 3d systems and software solutions. Fewer boreholes are needed to achieve a continuous picture of the subsurface thereby reducing overall costs and the risk of missing target features. A ray tracing approach to restoration and resolution enhancement in experimental ultrasound tomography show all authors. One borehole is used for source while other borehole is used for receiver. It analyzes wave speeds derived from arrival time data from the. List of tomography companies, manufacturers and suppliers.
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