Cross-Panel velocity and/or attenuation tomography (X-PanelTM) generates
images of anomalies in seismic velocity or attenuation within the volume
of surveyed ground using travel times or power loss of seismic waves that
travel between pairs of boreholes (panels), or between boreholes and an
accessible and sufficiently competent surface of the ground. The technique
closely resembles the medical CAT scan. The pattern of boreholes
determines if the images are two-dimensional (the fence profile) or
three-dimensional : typically when the panels intersect within the imaged
volume.
After all survey parameters are introduced and verified, the image is
generated in less than two hours dependent on the number of panels and
required resolution.
C-TG continues using
magnetostrictive actuator driven by a swept
frequency signal as
very repeatable and reliable seismic source
This approach allows transmitting controlled broad-band seismic waves into
the ground by significantly reducing loss of seismic energy in higher
frequency range due to plastic deformation of the ground. In turn,
broad-band seismic waves provide significant improvement in resolution for
both TRTTM
and X-PanelTM
techniques. This effect is particularly important for imaging piles as
part of bridge abutment and pier foundations to assess their type, depth,
patterns, and overall conditions.
C-TG also relies mainly
on using
accelerometers and pressure sensitive hydrophones
for detection of seismic signals. Sensitivity of these two types of
transducers is proportional to the second power of the frequency of
seismic vibrations. This type of response provides the most effective
compensation for frequency related exponential attenuation of seismic
waves in the ground.
TomoViewTM is a stand-alone graphic engine software that has
capabilities for
data input, survey coordinate verification, imaging local geology and site
conditions, adding comments, and enhancing analysis of processed ground
images for TRTTM in tunnels, X-PanelTM for
cross-hole site investigations, CSLTM for drilled shafts, and SHPS-TRT
TM for pier testing. It also allows exporting 3D files to AutoCAD.