Instrument Categories¶
Geotechnical instruments are grouped by what they measure. The four foundational categories below cover the vast majority of field-monitoring programs.
1. Lateral Movement¶
Instruments: Inclinometers, Tiltmeters, In-place Inclinometers (IPIs)
Applications: Slope stability, tunnel linings, retaining walls, landslide early-warning.
Principle: A probe or fixed array measures deviation from vertical along a guide casing installed in boreholes. Repeated surveys (or continuous IPI readings) reveal shearing planes and the depth of movement.
Typical readout: deviation-vs-depth profiles; cumulative displacement plots.
Representative instruments: Digital MEMS inclinometers, wireless tilt arrays..
Field Practice: Inclinometer Casing Installation (RST Instruments) Technology Demo: Real-Time ShapeArray (Measurand)
2. Subsurface Water¶
Instruments: Piezometers (vibrating wire, standalone, multi-level)
Applications: Pore water pressure monitoring, dam seepage detection, dewatering for excavations, groundwater studies.
Principle: A diaphragm and pressure transducer measure water pressure at a sealed filter tip. Vibrating-wire sensors convert pressure to a frequency signal that is robust over long cable runs.
Typical readout: hydraulic head (m) vs time; pressure (kPa).
Representative instruments: Vibrating wire piezometers, wireless piezometer nodes..
Field Practice: Taking Baseline VW Piezometer Readings (RST Instruments)
3. Deformation / Settlement¶
Instruments: Extensometers (rod, magnetic, multipoint), Settlement plates, Hydrostatic profile gauges
Applications: Embankments, soft-soil consolidation, deep excavations, pile load tests.
Principle: Anchor points at multiple depths are referenced to a surface datum. Relative movement between anchor and surface indicates compression/extension of the intervening soil/rock column.
Typical readout: settlement (mm) vs depth; ground-strain distribution.
Representative instruments: Borehole extensometers, magnetic extensometer spider systems..
Field Practice: Installing SAAV Extend ShapeArray (Measurand)
4. Load & Stress¶
Instruments: Load cells, Strain gauges, Stressmeters, Rock-bolt load cells
Applications: Foundation load tests, rock bolt stresses, bridge structural testing, tiebacks.
Principle: Direct measurement of force or strain via bonded resistance foil gauges, vibrating-wire load cells, or hydraulic flat jacks. Output converted to engineering units (kN, MPa).
Typical readout: load (kN) vs time; creep curves.
Representative instruments: Vibrating-wire load cells and strain gauges for structural monitoring.
Field Practice: Connecting Instruments to Dataloggers (RST Instruments)
How to Use This Page¶
| Goal | Suggested next step |
|---|---|
| Find Instrument specifications | Instrument Categories → |
| See real-world deployments | Applications → |
| Commissioning / installation procedures | Reference Manuals → |