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IIT Tirupati Navavishkar I-Hub Foundation Website
Problem Statement
Locating utilities beneath reinforced concrete structures is one of the most challenging tasks in subsurface investigations. The dense rebar mesh often produces strong reflections that mask deeper anomalies, making conventional detection methods unreliable. A non-destructive, broadband geophysical technique was needed to penetrate the reinforcement layer and identify underlying utilities without damaging the structure.
Overview
A Ground Penetrating Radar (GPR) survey was carried out using a 250 MHz ultra-wideband (UWB) antenna to detect utilities beneath a reinforced concrete slab. The aim was to resolve the interference caused by rebar signatures while still imaging deeper subsurface utilities.
Engineering Impact
Demonstrated GPR’s ability to detect utilities hidden under rebar mesh—a task often considered infeasible.
Provided a non-invasive, reliable alternative to coring or destructive investigations.
Enhanced safety during renovation, retrofitting, and drilling works.
Added value to facility management and infrastructure monitoring by offering precise digital subsurface records.
Conclusion
The use of 250 MHz UWB GPR with dense 3D survey design proved effective for utility detection beneath reinforced concrete slabs. This case study highlights GPR’s potential in addressing complex subsurface imaging challenges in civil and structural engineering contexts.
Methodology
System Configuration: 250 MHz UWB antenna offering deeper penetration and wide frequency coverage.
Survey Design: Data collected in dense 3D grids to enable depth-slice visualization of utilities masked by rebar clutter.
Processing Workflow: Advanced processing including background removal, migration, and frequency filtering was applied to suppress rebar responses and enhance deeper reflections.
Key Findings
Rebar Mesh Imaging: Clear, shallow hyperbolic patterns from reinforcement were recorded, confirming the presence and spacing of rebar.
Utility Detection: Despite rebar interference, utilities beneath the slab were successfully identified in depth slices, thanks to the penetration capability of 250 MHz UWB.
Subsurface Clarity: Volumetric visualization enabled separation of shallow rebar reflections from deeper utility responses.
Structural Insight: In addition to utilities, layering beneath the slab was imaged, supporting a more comprehensive structural health assessment.
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