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Geotomographie - Model BIS-SH -S-Wave Borehole Source
The borehole source BIS-SH generates horizontally polarized shear waves (SH) and compressional waves (P). This source is used for crosshole testing and S-wave tomography. The S-wave tomography links high-resolution borehole geophysics to soil dynamic properties. S-waves need to be generated with different polarization in order to be easily recognized during data processing. Due to its shorter wavelength compared to P-waves the S-wave provides a much higher resolution. The source works in dry or water filled boreholes and can be used in vertical or horizontal boreholes. The source is coupled to the borehole wall by a pneumatic clamping system. Mechanical impulses are released through manual or automatic triggering of the impulse generator (IPG5000) controlled by the remote control unit (RCU). The seismic signals are highly repeatable.The borehole source BIS-SH generates horizontally polarized shear waves (SH) and compressional waves (P) in dry or water filled boreholes.
Energy released by the IPG5000 discharges through a system of electromagnetical coils adjacent to a copper plate. If the plate is rejected a mechanical impact to the borehole wall is generated. The remote control unit (RCU) converts the reference signal of the impulse generator to an accurate time break with an accuracy of a few microseconds.The borehole source is coupled to the borehole wall by a pneumatic clamping system (inflatable bladder). The orientation of the source is controlled from surface by a torsionally stiff hose.
Test showed that the S-wave source BIS-SH is highly repeatable up to frequencies of 4-5 kHz.
- Generated wave types: SH/P
- Signal frequencies: Up to 4 kHz (depending on geology and borehole distance)
- Operational depth: Up to 100 m
- Source length: 880 mm
- Source diameter: 65 mm
- Source weight: 8.5 kg
- Cable weight per metre: 665 g
- Borehole diameter: 75 - 100 mm (or larger if spacers are used)
- Clamping system: Inflatable bladder
- Orientation: Torsionally stiff hose
- Depth indicator: Cable marking every 2 m
- Connector: To Impulse Generator IPG5000