The crosshole test provides a depth profile of shear wave velocities (VS) and compressional wave velocities (VP) between boreholes at a high vertical resolution. The method is used to determine soil dynamic parameters, such as shear modulus, Poisson ratio and Young’s modulus. Engineers use these key parameters to predict the response of soils to dynamic loading.
Depths shallower than 60 m
In general, the crosshole test is used for shallow geotechnical investigations mostly in depths until around 60 m. Especially for this shallow application an extra leight-weight and cost-effective crosshole system supplied by a power of 800 V is proposed.
Source
BIS-SH-DS | S-Wave Source
The borehole source BIS-SH-DS generates horizontally polarized shear waves (SH) and compressional waves (P). The seismic signals are highly repeatable. The source works in dry or water filled boreholes and can be used in vertical or horizontal boreholes. Energy released by the IPG800 discharges through a system of coupled coils. They generate a mechanical impact to the borehole wall that releases seismic waves.
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.
Download product sheet.pdf
Receiver
BGK5 | Borehole Geophone
The borehole geophone BGK5 is used to receive P- and S-waves in dry or water filled boreholes. The borehole geophone BGK5 consists of four horizontal sensors, separated by 45° intervals, and one vertical sensor. The geophone is coupled to the borehole wall by a pneumatic clamping system (inflatable bladder). Air is supplied to the BGK5 through an electro-pneumatic hybrid cable with a Kevlar tension string. The cable is terminated by a connector to the seismograph.
Download product sheet.pdf
Power supply
IPG800 | Impulse Generator
The Impulse Generator IPG800 is the high voltage supply to the seismic borehole source BIS-SH-DS. The energy is stored in capacitors which discharge through a mechanical switch. The lightweight IPG800 is incorporated in a robust PeliTM case.
The IPG800 is operated by a Remote Control Unit (RCU) which is used to start a pre-defined sequence of shots or to stop the operation. The RCU is connected to the seismograph to send an accurate trigger signal.
Download product sheet.pdf
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Depths greater than 60 m
In case of deeper underground investigations the performance of crosshole test requires a more powerful and heavier crosshole system that works with 5000 V and is applicable in depths greater 60 m.
Source
BIS-SH | S-Wave Source
The borehole source BIS-SH generates horizontally polarized shear waves (SH) and compressional waves (P). The seismic signals are highly repeatable. The source works in dry or water filled boreholes and can be used in vertical or horizontal 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 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.
Download product sheet.pdf
Receiver
BGK3/7 | Borehole Geophone
The borehole geophone BGK3 is used to receive P- and S-waves in dry or water filled boreholes. The borehole geophone BGK3 consists of a tri-axial sensor whereas the BGK7 consists of six horizontal sensors, separated by 30° intervals, and one vertical sensor. The geophone is coupled to the borehole wall by a pneumatic clamping system (inflatable bladder). Air is supplied to the BGK3/7 through an electro-pneumatic hybrid cable with a Kevlar tension string. A magnetic compass shows azimuthal deviation to North and can be used to get the orientation of the geophone in the borehole. The cable is terminated by a connector to the seismograph.
Download product sheet.pdf
Power supply
IPG5000 | Impulse Generator
The Impulse Generator IPG5000 (formerly named IPG1005) is the high voltage supply to the seismic borehole sources BIS-SH and SBS42. The energy is stored in a large capacitor bank which discharges through a mechanical switch.
The IPG5000 is controlled by a Remote Control Unit (RCU). The RCU allows the user to start the seismic survey by a single or continuous shot release. The repetition rate is freely selectable under continuous operation. The RCU is connected to the seismograph to send an accurate trigger signal.
