NEW NON-DESTRUCTIVE INSPECTION METHOD WITH GROUND PENETRATING RADAR TO
EVALUATE THE SUITABILITY OF THE BACKFILLING GROUTING INJECTION IN TUNNEL
This research focuses on the development of a new non-destructive
inspection method, based on the interpretation of electromagnetic waves
by means of a ground penetrating radar (GPR), in order to evaluate the
condition of the backfilling two-component mortar grouting behind the
segmental lining in tunnels made by tunnel boring machines (TBM). The
data processing by digital models and the analysis of the propagation
speed of the along the backfilling grouting layer have enabled the
technical and operational feasibility of this novel inspection method.
Once the conceptual framework of the research was defined, it was
possible to validate the developed method in a full-scale operational
environment in the Metro of Quito Line 1 (Ecuador). This validation
involved a battery of tests collating the results obtained through the
core-drilling extractions in comparison with the ones obtained with GPR.
As a result of these calibration tests, it was possible to identify a
range of propagation speeds linked to grouting in optimal execution
conditions, as well as other ranges associated with potential anomalies.
Finally, it was possible to implement this new inspection methodology on
a regular basis in the Metro of Quito, where the conventional quality
control by core-drillings was replaced almost entirely for the new
method with GPR.