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-TRTTM for pier
testing. It also allows exporting 3D files to AutoCAD.
