Geotechnics · DSS · DTS · DAS · OFDR · FBG
Start with the measurement question, then select the fibre-optic technology
There is no single “DFOS geotechnical sensor”. Vibration, temperature, slow deformation, a dense local profile and critical points require different equipment.
landslides and slopeslevees and damsembankments and tunnelsstrain, temperature and vibration
DAS mainly measures dynamic phenomena, DTS temperature, DSS/DTSS long-range static strain, OFDR a very dense profile over a shorter section, and FBG selected points. These technology names are not interchangeable.
A fibre-optic sensor measures a physical quantity transferred to the fibre. Displacement, settlement or stress may require a model, sensor geometry, temperature compensation and boundary conditions. A robust monitoring architecture can combine DFOS with surveying, inclinometers or piezometers.
What is the geotechnical question?
Select the technology by the phenomenon, length scale and required spatial resolution.
Where is slow deformation developing?
DSS/DTSS creates a static-strain profile that can be compared with the baseline and subsequent campaigns.
Where is seepage occurring?
DTS observes thermal anomalies; active DTS can analyse the ground’s thermal response.
Where is vibration occurring?
DAS records seismic activity, traffic, machinery and other dynamic events.
What is happening in a short critical section?
ODiSI/OFDR provides a dense strain profile over a selected section, while FBG measures critical points.
Technology selection matrix for geotechnical monitoring
Length, resolution and measured quantity matter more than one maximum-range figure.
| Phenomenon / objective | Technology | What it provides | INTERLAB portfolio |
|---|
| vibration, seismicity, machinery | DAS | dynamic strain and a time–distance signal | iDAS-MG, QuantX |
| seepage and thermal anomalies | DTS / active DTS | temperature profile and thermal response | ULTIMA, XT-DTS |
| settlement and slow slope movement | DSS / DTSS | long-range static-strain profile | Silixa iDSS, fibrisTerre |
| critical section of 20–100 m | OFDR / HD-FOS | dense strain or temperature profile | ODiSI 7100 |
| critical point | FBG | tilt, displacement, strain, temperature or vibration | HYPERION and OS sensors |
Important: DAS is not the default method for slow settlement. ODiSI does not measure settlement directly, and FBG is a point or multipoint sensing system rather than continuous DFOS.
The INTERLAB portfolio from kilometres to millimetres
Each platform has a different role in the measurement architecture.
DSSSilixa iDSS
Long-range static-strain profiling for slopes, settlement and infrastructure.
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BrillouinfibrisTerre
Distributed strain and temperature measurement for geotechnics and natural geohazards.
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OFDRODiSI 7100
High-resolution measurement over a selected section where metre-scale resolution is insufficient.
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DASSilixa iDAS-MG
Dynamic phenomena, microseismic monitoring and flexible DAS measurement configurations.
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DTSSilixa ULTIMA
Temperature profiling for seepage, leakage and thermal testing after suitable sensing-cable design.
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FBGHYPERION si155
A platform for point-sensor networks measuring strain, temperature, tilt, displacement, pressure and vibration.
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The measurement chain starts with the cable
Mechanical coupling and compensation are part of the result.
Define the phenomenon
Strain, displacement, temperature and vibration are not the same parameter.
Select the cable construction
A strain-coupled cable transfers deformation, while loose-tube construction can support temperature measurement or compensation.
Establish the reference
A baseline, temperature and boundary conditions allow the trend to be interpreted.
Combine methods
Surveying, inclinometers and piezometers provide an absolute reference and validation.
Frequently asked questions
What is the difference between DAS, DTS, DSS, OFDR and FBG?
DAS mainly measures vibration, DTS temperature, DSS a long-range profile of static strain, OFDR a very dense profile over a short section, and FBG selected points.
Which technology is suitable for a landslide?
DSS/DTSS is a natural candidate for slow deformation. DAS can add dynamic events, while FBG can monitor critical points.
Does ODiSI measure settlement directly?
No. It measures fibre strain or temperature. A displacement profile requires a sensor geometry, reconstruction model and boundary conditions.
Can DTS detect seepage through an embankment?
It can indicate thermal anomalies associated with water flow. Active DTS can be used where the natural thermal contrast is weak.
Does DFOS replace inclinometers and surveying?
No. These technologies measure different quantities. The most reliable picture comes from combining methods.
Is ordinary telecom cable sufficient?
DAS can often use existing fibre, but static-strain and temperature measurement requires an appropriate cable construction and controlled coupling.
Select equipment for the measured phenomenon and scale of the asset
Send us the asset cross-section, deformation mechanism, cable plan, length, required resolution and list of existing instruments.
Technical sources: Silixa iDSS · fibrisTerre · Luna ODiSI 7100 · sensor–ground coupling
