GS4 Ground Imaging Tomography

The GS4 Ground Imaging system uses finite differencing wave propagation and automatic signal processing techniques to quickly obtain high resolution, accurate 3D ground images. It illustrates significant advancements in 2D and 3D seismic refraction data processing and presentation.  We provide fast, high quality 3D seismic data processing service. The following are examples of 3D seismic data interpretation projects.

Assessing the effectiveness of compaction grouting.
Detecting dam scour depths.
Mapping bedrock.

Assessing the effectiveness of compaction grouting

Rapid and inexpensive seismic method was utilized by Ability Industries ltd in Rocky Mountain National Park, Haifa, during rehabilitation of a historic placed-rock armored slope structure located below roadway grade along the outboard lane.  The GS4 software was used to generate accurate before-grouting and post-grouting volumetric difference images that depicts the effect of grouting, including the resultant grout columns and ground densification characteristics.
 

GS4 software incorporates time, frequency, and velocity filters, and uses advanced pattern matching analysis of the signal spectrogram as well as the waveform to automatically determine consistent travel time picks.  GS4estimates travel times by propagating a wave across a continuous velocity model using wave front vector interpolation, resulting in efficient and accurate travel time estimates. This technique quickly converges to the solution of minimum travel time error with minimum velocity variation, providing consistent results.

Detecting dam scour depths 

Seismic signals collected on dam surface were processed by GS4 software. 3D volumetric ground image which engineers can easily interpret were provided. The detected scour hole is represented by the pink color in the tomography, the position and volume can be viewed in detail by slicing, zooming and rotating. The 3D tomography result can be sliced in X, Y, Z direction as well as by its physical character, the velocity, or the density of the material. We provide fast, high quality 3D seismic data processing service

GS4 sensor strings were laid on top of concrete road. Hammer was hit next to each sensor to generate seismic waves. A water pipe under the road was revealed within 20 minutes after finishing data collection.

Hardware

• Motes with one or four, 10Hz-10kHz range accelerometers, digitize and store signal, automatic trigger detection with pre-trigger sampling, high-speed data transfer, dynamic PGA for broad dB range, signal conditioning, and oversampling.

• Cables rugged with metal connectors.

• Power with 12V battery powers up to 12 motes or 80' of sensor string.

• Laptop with Ethernet adapter, supports up to 100m Ethernet cable connection between laptop and motes. Image processing device – 32 asics block + arm processor communication controller