Optical Borehole Inspection with the DMT SlimBoreholeScanner

The DMT Slim Borehole Scanner is the ideal solution for structural and geotechnical analyses of rock and soil and geotechnical investigations in geology and engineering. The tool for optical inspection and documentation offers highly precise monitoring for slim and short boreholes and early detection of a possible fault in tunnel construction as well as other applications. In addition, it can be employed as a mobile monitoring tool for the determination of fracture widths.

The device can be manually operated with a borehole diameter between 1" and 1.8”. It is lightweight and easy to use. Therefore, it is ideally suitable for regular inspection and scanning of, for example, roof bolt holes drilled in rock for tunnel construction projects.

Accurate and Comprehensive Inspection of Geological Structures

During insertion in a drilled hole, the scanner is illuminated by a ring of LEDs. The camera captures 360° images from the walls of the borehole. These images are stacked slice by slice to provide an image of the complete borehole. This method of frequently sampling boreholes delivers optimized data where every set of measurements or every borehole can be compared with each other. 

DMT's Slim Borehole Scanner is a self-confined unit powered by internal batteries. All measurements are stored on an internal storage memory and can be accessed immediately after sampling. Optional database-, readout or interpretation software allow for easy handling of large amounts  of measurements and safety qualifications of rock. The software can be used to semi-automatically measure and determine the width of a fault.


Applications of Geophysical Borehole Logging in Civil Engineering

Thanks to the database, the current scans of the structure can be compared with older borehole scans, providing an easy way to measure progress and changes during the construction process. With the Borehole Scanner, the three-dimensional positions of the interfaces of the roof of the tunnel can be determined.The geological methods also allow for early detection of a possible fault such as fracture zones and quick reactions to any difficulties encountered during the construction of a tunnel. Rock disruption and rock mass structure can be assessed as well as other structural features of the tunnel. This method enables the engineer to update the geological-geotechnical model of the tunnel during the construction process, improving precision and reliability of the geological model.

Applications of Borehole Logging for Injection Techniques

The borehole logging method offers serveral advances for injection techniques. The borehole scanner can be used to detect cavities and determine openings of discontinuities, für example of joints and faults. Mineralized or open joints can be detected through analysis of the borehole images. The SlimBoreholeScanner enables its user to asses the rock disruption and thus optimise the injection techniques according to on-site rock conditions. Finally, it allows for documentation of successful injections. Borehole logging offers benefits for the whole lifetime of a roadway.

Benefits of Borehole Scanning for Engineers and Scientists

With the DMT Slim Borehole Scanner advances the scientific aspects of visual inspection applications in engineering by visualizing rock structure under the surface of the earth. The subsurface exploration system provides samplings for further investigations and evaluations.

It is the perfect device to avoid any incorrect instructions and the most appropriate tool for on-site inspection of subsurface conditions and geological structures. To prevent faulty observations, this instrument assists scientists in assessing the accuracy and applicability of their estimations. This high precision monitoring device will prove itself to be highly useful for civil engineering applications as well as scientific observations on-site and in laboratory environments. The borehole scanner also has an option for intrinsical safety for mining applications, for example in coal mining with ATEX certification [ I M1 Ex ia I M1 ].

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