GPR void detection — subsurface cavities and karst mapping with ground penetrating radar

Subsurface Risk Engineering: GPR Survey for Voids, Mine Workings & Ground Instability

We use the Loza electromagnetic survey system to locate what creates risk before it becomes a failure: hidden voids, karst cavities, abandoned mine workings, seepage channels, and weak zones causing subsidence and sinkholes.

Void & cavity mapping: karst, solution pipes, washed zones, air-filled voids

Abandoned mine workings: stopes, shafts, chambers — including those absent from old plans

Subsidence & sinkhole risk: settlement, differential compression above disturbed ground

Infrastructure corridors: roads, pipelines, construction sites — paleorelief traps and weak soil lenses

Fault & fracture structures: discontinuities, groundwater discharge pathways

Dam & embankment integrity: seepage, suffosion, internal erosion, piping channels

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How subsurface failures develop — and where GPR intercepts the process

Leakage / Infiltration

→

Suffosion / Soil washing

→

Void / Loose zone

→

Settlement

→

Collapse / Failure

Ground penetrating radar detects the process at the leakage → suffosion → void stage — when remediation costs are a fraction of post-collapse repair. We have surveyed infrastructure across 63 countries in Africa, Asia, Europe, and South America.

Survey deliverables (decision-ready output)

Risk zoning map: where to investigate, reinforce, or avoid

Depth profiles tied to the engineering task — not raw radargrams

Void geometry and depth estimates within site conditions

Priority drilling recommendations: where to verify first

Correlation with existing geology, boreholes, and project constraints

2D conductivity and permeability proxy sections for fluid and void discrimination

Targets

Karst & cavities
Stopes & shafts
Faults & fractures
Paleochannels / buried ravines
Dams & embankments

Risks

Subsidence / sinkholes
Internal erosion / piping
Leakage & saturation
Slope instability
Infrastructure damage

Actions

Reinforcement / grouting
Drainage & water control
Route adjustment
Targeted drilling
Monitoring plan

Geotechnical risk mapping — GPR sections showing void zones and disturbed ground

Why our surveys reach what others miss

Most geophysical services for engineering tasks are limited to shallow investigation depths — sufficient for utility mapping, but not for detecting buried mine workings, deep karst cavities, or seepage zones in dam foundations. The Loza electromagnetic system operates at dipole frequencies down to 25 MHz, providing investigation depth sufficient for the geotechnical targets that actually matter: abandoned stopes, deep suffosion channels, bedrock faults below fill.

The system records the full electromagnetic response — structural and conductive — in a single survey pass. This means voids, fluid pathways, and weak zones are resolved simultaneously, without requiring separate surveys or method combinations.

Abandoned Mine Workings Detection: Stopes, Shafts & Chambers

Abandoned vertical workings are among the most dangerous geotechnical hazards. They are frequently absent from historical mine plans — and surface collapse typically occurs without warning, often under roads, buildings, or active mine infrastructure.

The Loza electromagnetic system is particularly effective for detecting large-form voids, backfilled stope zones, disturbed crown pillar areas, and high-risk collapse zones before you place heavy infrastructure or commission ground-level operations above them.

Kryvyi Rih, Ukraine — 2021 GPR detection of abandoned mine stopes — Kryvyi Rih iron ore basin, Ukraine 2021

Stope and disturbed zone mapping Ground penetrating radar section showing stope boundaries and crown pillar weakening

Work Examples: Underground Utility Detection & Pipe Mapping

GPR detection of underground communications and buried pipes

Resolution across different pipe diameters GPR radargram showing pipes of different diameters — depth and position mapping

Ground penetrating radar section — buried pipe detection and depth estimation

Pipe identification and lateral tracing GPR pipe identification — horizontal section showing utility corridor layout

3D section — pipe cluster localization 3D GPR section showing localization of buried pipe cluster and utility corridors

Water leak detection in buried pipes GPR detection of water leaks — saturated soil anomaly around buried pipe

Karst Cavity Detection and Sinkhole Risk Mapping

Karst is a progressive failure mechanism: dissolution opens cavities, weakens the rock roof, and generates sudden sinkhole collapse without surface precursors. The Loza system resolves cavity geometry, roof thickness, and infill state (air-filled vs. water-saturated) — the distinction that determines whether remediation is possible or urgent.

Karst sinkhole collapse — surface expression

Karst sinkhole collapse — surface manifestation of subsurface cavity failure

GPR radargram — karst cavity detection Ground penetrating radar section showing karst cavity roof and void geometry

GPR Analysis of Building Foundations and Subslab Voids

Foundation GPR survey identified zones of active infiltration, fracturing, and preferential groundwater flow pathways beneath the building footprint. Risk zoning allowed targeted remediation — without full excavation.

$GPR survey of building foundation — infiltration zones and fracturing mapped in 2D sections$

Problem zones in office building foundation Foundation risk map derived from GPR survey — weak zones and water infiltration areas highlighted

Infrastructure Corridor Surveys: Roads, Pipelines, Linear Projects

Buried paleorelief is a systematic trap for linear infrastructure: old channels, hidden ravines, saturated lenses, and compressible peat layers that re-activate under load and generate differential settlement. GPR corridor mapping at 200–500 m/day covers alignments efficiently and flags risk zones before construction decisions are locked in.

Pipeline route — GPR geotechnical survey

Bedrock depth mapping, soil quality assessment, and integrity evaluation along the pipeline corridor.
1. Pre-construction risk reduction.
2. Informed route and design decisions.

GPR survey for pipeline construction — bedrock depth and soil quality mapping along route corridor

Road corridor — sinkhole and weak zone detection GPR road survey — sinkhole risk detection and subsurface void mapping beneath road corridor

Dam and Embankment Inspection: Seepage, Piping & Internal Erosion

Dam failures follow a predictable sequence: leakage → suffosion → piping channel → void → breach. The Loza system resolves this process at the seepage and early suffosion stage — when intervention cost is 1–2% of a post-failure remediation.

Seepage zone detection in earthfill dam

Loza-2N system, 6 m antenna (25 MHz). Fill thickness surveyed: up to 20 m. Leakage zones identified at 155 m and 180–200 m along dam axis.

GPR radargram of earthfill dam — seepage zone detection at 25 MHz, Loza-2N system

Dam body inspection — Far East, Ukraine Ground penetrating radar section across dam body — internal structure and moisture anomalies

Internal erosion — structural damage zones GPR section showing internal erosion damage zone within dam structure

Dam survey — Kazakhstan GPR dam inspection Kazakhstan — piping channel and seepage anomaly mapping

Fault structures and heterogeneity in dam body GPR radargram — fault-type structures and material heterogeneity in dam cross-section

Survey resolved fault-type discontinuities and significant material heterogeneity in the dam body — including zones of elevated seepage risk.

Loza-2N system, 6 m antenna (25 MHz).

Dam inspection — Kryvyi Rih, 2020 GPR dam inspection Kryvyi Rih Ukraine 2020 — seepage and structural integrity survey

Underwater GPR: Bathymetry, Sediment Profiling & Bedrock Mapping

Subsurface mapping through water — application areas:

Freshwater lakes and reservoirs

Rivers and water courses

Reservoir sedimentation surveys

Tailings pond bottom profiling

Subsurface parameters resolved:

Bedrock surface depth and morphology

Stratigraphic boundaries in sediment column

Sediment type and compaction state

Contamination layers (fuel oil, heavy sediments)

Through-water GPR — lake bottom survey Loza-2N GPR survey through water — lake bottom sediment profiling and bedrock depth mapping

Through-water GPR operation:
Lake bottom sediment mapping, bedrock depth

Loza-2N, 3 m antenna (50 MHz)

Turkey — reservoir sediment survey Underwater GPR survey Turkey — reservoir sediment stratigraphy and bedrock profiling

GPR survey for fuel oil contamination — lake bottom mapping GPR through-water survey — fuel oil contamination volume assessment at lake bottom

To assess fuel oil volume at the lake bottom, GPR soundings were conducted from the water surface. The Loza system was insulated from contamination and operated on foam floats, dragged from shore to shore at 1 measurement/second. Survey resolved heavy fuel oil deposits of 1.5–5 m thickness filling bottom depressions.

GPR section — lake bottom stratigraphy: water layer, fuel oil deposit, clay substrate

1. Water
2. Bottom depression filled with heavy fuel oil deposits
3. Clay substrate