Crosshole equipment

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.

BIS SH DS

Generated wave types:

SH/P

Signal frequencies:

Up to 4 kHz (depending on geology and borehole distance)

Operational depth:

Up to 60 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 IPG800

Storage:

On drum

 

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.

bgk5

Natural sensor frequency:

10 Hz (others on request)

Sensor arrangement:

4 horizontal (45°)/1 vertical

Operational depth:

Up to 100 m

Receiver length:

600 mm

Receiver diameter:

51 mm

Receiver weight:

2.8 kg

Cable weight per metre:

145 g

Cable strength:

2150 N

Borehole diameter:

75 mm (or larger if spacers are used)

Clamping system:

Inflatable bladder

Depth indicator:

Cable marking every 2 m

Connector:

To any seismograph

Storage:

On drum

 

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.

IPG800

Impulse voltage:

800 V

Impulse energy:

1000 J

Power supply:

2 x 12 V (car batteries)

Shot release:

Single or continuous (5/10 shots)

Repetition rate:

10 s

Dimensions:

53 x 43 x 23 cm

Weight:

15 kg

Special features:

Impulse counter

 

Test trigger

 

Emergency OFF button

RCU:

Start/stop operation

 

Trigger output

 

Emergency OFF button

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.

bis sh

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

 

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.

bgk3 7

Natural sensor frequency:

10 Hz (others on request)

Sensor arrangement:

Tri-axial (BGK3) or 6 horizontal (30°)/1 vertical (BGK7)

Operational depth:

Up to 100 m

Receiver length:

705 mm

Receiver diameter:

50 mm

Receiver weight:

3 kg

Cable weight per metre:

145 g

Cable strength:

2150 N

Borehole diameter:

75 mm (or larger if spacers are used)

Clamping system:

Inflatable bladder

Orientation:

Magnetic compass (+/-2.5°)

Depth indicator:

Cable marking every 2 m

Connector:

To any seismograph

Storage:

On drum

 

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.

ipg5000 2

Impulse voltage: 5000 V
Impulse energy: 1000 J
Power supply: 230 V/110 V
Shot release:  Single or continuous 
Repetition rate: 8 s (or freely selectable between 3 and 8 s)
Dimensions: 52 x 32 x 53 cm
Weight: 60 kg
Special features:
  • Impulse counter
  • Test trigger
  • Emergency OFF button
  • Intern/Extern operation
RCU:
  • Single or continuous shot release
  • Impulse counter
  • Test trigger
  • Trigger output
  • Emergency OFF button