Three-dimensional Reflector Tracing system (TRTTM) records seismic waves
generated and detected by an array of sources and receivers coupled to the
ground in boreholes. For applications in advancing tunnels TRTTM uses 3D
'tube array' of sources and receivers coupled to the tunnel walls. The
technique resembles medical ultra-sound imaging. Stacking and
triangulation of recorded waves generates color-coded anomalies at the
reflector locations within the volume of surveyed ground. These images of
reflectors are considered reliable as far as 300ft/100m from the array
dependent on the type of ground. The magnitude of an anomaly is
proportional to the absolute change in seismic impedance (product of
velocity and natural density) at the reflector boundary. The blue to
purple color of the anomaly indicates ground changing from higher to lower
seismic impedance, while yellow to red indicates higher seismic impedance.
After all survey parameters are introduced, the image is generated in less
than an hour.
C-TG 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.