Chapter 25 — Geotechnical Instrumentation and Monitoring (Digest)¶

Source: CFEM 2022 (4^th Edition), Chapter 25, by Pierre Choquet, Dr.-Eng., P. Eng. This page is an original digest with an elaborated reference section; it is not a reproduction of the copyrighted chapter.

Geotechnical design embraces uncertainty. That uncertainty is assessed during construction and operation using instruments. Chapter 25 surveys the instruments commonly used to monitor the short- and long-term behaviour of the ground supporting man-made structures, together with the data-collection and acquisition systems behind them.

The chapter is organised around six measured parameters, and this digest follows that structure before turning to the autonomous half of the subject — how readings are taken, transmitted, and presented without a person in the field.

25.1 — Introduction¶

The six principal monitoring parameters, and the instruments that measure them:

Parameter	Typical instruments
Groundwater pressure	Piezometers (standpipe, vibrating-wire, pneumatic, push-in, fully-grouted)
Displacement (surface and depth; x, y, z; relative or absolute)	Extensometers, settlement gauges, inclinometers, tiltmeters, geodetic methods
Strain (on ground or structure surfaces, or embedded)	Strain gauges
Load (structural element → ground)	Load cells (tie-back anchors, test piles)
Total pressure (ground–structure contact)	Hydraulic total pressure cells
Temperature (surface, or profile with depth)	Thermistors

The chapter also covers geodetic methods — total stations, levelling, differential RTK GPS, and newer methods such as LiDAR, ground-based InSAR and satellite InSAR — because they are used alongside geotechnical and structural instrumentation.

25.2 — Information sources (elaborated)¶

This is the section that makes the chapter a reference tool. Rather than a plain bibliography, §25.2 is a guided reading list organised by document type. Below, each entry is grouped and annotated with what it is and why it matters.

25.2.1 — The foundational textbook¶

Geotechnical Instrumentation for Monitoring Field Performance — John Dunnicliff (1993), Wiley, 577 pp. — the discipline's standard work, universally known as the "Red Book". Chapter 25 treats it as the single most recognised source in the field.
Dunnicliff's quarterly columns in Geotechnical News (CGS) — 93 columns, indexed and searchable in the public section of the CGS website. A running practitioner archive that extends the book.

25.2.2 — Textbooks and major guideline volumes¶

Reference	Coverage
De Rubertis, K. (Ed.), 2018 — Monitoring Dam Performance: Instrumentation and Measurements, ASCE, 442 pp.	The chapter's main source for metrological properties (§25.5) and geodetic monitoring; the ASCE/USSD dam-safety reference
Sharon, R. & Eberhardt, E. (Eds), 2020 — Guidelines for Slope Performance Monitoring, CSIRO Publishing / CRC Press, 331 pp.	Slope-specific monitoring philosophy and practice
Stark, Oommen & Ning, 2021 — Remote Sensing for Monitoring Embankments, Dams, and Slopes, ASCE GSP 322, 114 pp.	Remote-sensing state of practice (InSAR, LiDAR, photogrammetry)
ICE Manual of Geotechnical Engineering (Burland et al., 2012) — Ch. 94 Principles of Geotechnical Monitoring (16 pp.) and Ch. 95 Types of Geotechnical Instrumentation and Their Usage (26 pp.)	A second canonical treatment; Ch. 94 also covers contract practices
Walker & Awange, 2020 — Surveying for Civil and Mine Engineers, Springer, 411 pp.	Geodetic/surveying methods (§25.17)
Glisic & Inaudi, 2007 — Fibre Optic Methods for Structural Health Monitoring, Wiley, 281 pp.	The reference for fibre-optic sensing (§25.4.4)
Ferretti et al., 2007 — InSAR Principles: Guidelines for SAR Interferometry Processing, ESA TM-19	The principles behind satellite InSAR (§25.17.5)
Chartered Institution of Civil Engineering Surveyors, 2017 — Client Guide to Instrumentation and Monitoring, Survey Liaison Group, London, 28 pp.	Client-side procurement and scope guidance

25.2.3 — Standards¶

ASTM Subcommittee D18.23 (Field Instrumentation) — the US standard test methods and practices directly governing specific instruments:

Standard	Subject
D4403-20	Standard Practice for Extensometers Used in Rock
D6230-13	Standard Test Method for Monitoring Ground Movement Using Probe-Type Inclinometers
D6598-19	Standard Guide for Installing and Operating Settlement Points for Monitoring Vertical Deformations
D7299-12	Standard Practice for Verifying Performance of a Vertical Inclinometer Probe
D7764-12	Standard Practice for Pre-Installation Acceptance Testing of Vibrating Wire Piezometers

ISO Technical Committee 182 / WG2 — the ISO 18674 series ("Geotechnical investigation and testing — Geotechnical monitoring by field instrumentation"), the international counterpart, published part by part:

Part	Subject	Status at time of writing
ISO 18674-1:2015	Part 1: General rules	Published
ISO 18674-2:2016	Part 2: Measurements along a line — extensometers	Published
ISO 18674-3:2017	Part 3: Measurements across a line — inclinometers	Published
ISO 18674-4	Part 4: Measurement of pore water pressure — piezometers	Published
ISO 18674-5	Part 5: Stress change measurements by total pressure cells	Published
Part 6 / 7 / 8 / 9	Hydraulic settlement gauges / strain gauges / load cells / geodetic monitoring instruments	Planned

DIN (Deutsches Institut für Normung) — vibration standards cited for §25.19:

DIN 45669-1:1995 — Mechanical vibration and shock measurement
DIN 4150-1:2001 — Structural vibration, Part 1: prediction of vibration parameters
DIN 4150-2:1999 — Human exposure to vibration in buildings (under revision)
DIN 4150-3:2016 — Vibrations in buildings, Part 3: effects on structures

Other agency standards and guidelines:

Transportation Research Board (TRB), 2008 — Use of Inclinometers for Geotechnical Instrumentation on Transportation Projects (Machan & Bennett) — a comprehensive technical note on inclinometer practice.
USGS, 2008 — Instrumentation Guidelines for the Advanced National Seismic System (ANSS), Open-File Report 2008–1262, 48 pp. — the source of the Class A–D strong-motion system classification used in §25.18.
COSMOS, 2016 — Guidelines and General Considerations for Strong-Motion Instrumentation of Tall Buildings — strong-motion guidance for tall structures.
US Bureau of Mines RI 8507, 1980 (Siskind et al.) — Structure Response and Damage by Ground Vibration from Mine Blasting — the classic blasting-vibration reference underlying §25.19.

25.2.4 — Regulation and manual references (dam safety)¶

The chapter's list of downloadable dam-safety instrumentation guidelines — the regulatory manuals that a monitoring programme is ultimately accountable to:

Manual	Publisher / year	Size
EM 1110-2-1908 — Instrumentation of Embankment Dams and Levees	U.S. Army Corps of Engineers, 2020	290 pp.
EM 1110-2-4300 — Instrumentation for Concrete Structures	U.S. Army Corps of Engineers, 1987 (under revision)	306 pp.
Embankment Dam Instrumentation Manual (Bartholomew, Murray & Goins)	U.S. Bureau of Reclamation, 1987 (under revision)	269 pp.
Concrete Dam Instrumentation Manual (Bartholomew & Haverland)	U.S. Bureau of Reclamation, 1987	153 pp.
Engineering Guidelines for the Evaluation of Hydropower Projects, Ch. 9 Instrumentation and Monitoring (2005); Ch. 14 Dam Safety Performance Monitoring Program (2017)	FERC	86 / 188 pp.
ICOLD Bulletin 158 — Dam Surveillance Guide (2018)	ICOLD	109 pp.
7 White Papers on Development and Implementation of Dam Safety Monitoring Programs (2008–2020)	U.S. Society on Dams (USSD)	series
Manual de Mecánica de Suelos: Instrumentación y Monitoreo del Comportamiento de Obras Hidráulicas (2012)	Comisión Nacional del Agua, Mexico	322 pp.

Cross-reference. The site digests several of these directly — see Monitoring Dam Performance (ASCE MOP-135) and Tailings Dam Safety (ICOLD Bulletin 194).

25.2.5 — Symposia series¶

Comprehensive instrumentation research has been published through the "Field Measurements in Geomechanics" (FMGM) symposia: Zurich 1983, Kobe 1987, Oslo 1991, Bergamo 1995, Singapore 1999, Oslo 2003, Boston 2007, Berlin 2011, Sydney 2015 and Rio de Janeiro 2018 — organised by volunteers (mostly academics) and published commercially. The next symposium was scheduled for London 2022 under ISSMGE sponsorship. These proceedings are where instrumentation case histories are reported in detail.

25.3 — Human factors¶

Chapter 25 devotes early attention to human factors, drawing on three Dunnicliff chapters: systematic planning, specifications for procurement, and contractual arrangements. Its argument is enduring: simple mechanical/hydraulic instruments once worked in the hands of diligent engineers with a clear sense of purpose; as technology advanced, "an increasing number of instrumentation programmes have been in the hands of people with incomplete motivation and sense of purpose," and many failures became failures of the instrument–person marriage rather than of the instruments. Written decades ago, the chapter notes the point is "if not even more so" today, given the faster pace of construction.

25.4 — Measuring principles¶

Geotechnical instruments rest on electrical, mechanical, hydraulic and pneumatic principles. The two dominant electrical principles:

Vibrating wire (VW) — by far the most prevalent. A pre-tensioned steel wire (typically 0.25 mm diameter, 5–15 cm long) is excited by two electromagnetic coils; the wire resonates at a frequency (1,000–2,000 Hz) that varies with tension. Proven in European concrete dams after WWII for robustness and long-term stability; now spans pore pressure, settlement, extension/compression, strain, load, stress and earth pressure. Temperature is often built in via a sealed thermistor.
MEMS accelerometers — superseded servo-accelerometers and electrolytic tilt sensors around 2010 for tilt and inclination, with equal or better metrology plus better robustness and temperature-offset behaviour. Circuits can include a microcontroller and ADC, giving digital output on an RS-485 bus.
Digital-output instruments (a related family) — piezoresistive water-level sensors with 4–20 mA output, multi-parameter water-quality probes, and digital thermistor strings, using RS-485 or the USGS-developed SDI-12 protocol.
Fibre-optic sensing — immune to lightning and electrical transients; available as point sensors, semi-distributed (Bragg-grating) and fully distributed (Brillouin scattering, strain/temperature every metre over cables up to 30 km).

25.5 — Metrological properties¶

Because instruments are often irreplaceable once installed, excellent metrology is expected. The properties (after De Rubertis, 2018), with typical VW values:

Property	Meaning	Typical VW value
Resolution	Smallest distinguishable change	Many times finer than accuracy
Accuracy	Match to an acceptable standard	±0.1 % F.S. (NIST-traceable)
Precision (random error)	Closeness to the mean of repeated readings	±0.025 % F.S.
Repeatability	Agreement of consecutive measurements	Same as precision (VW)
Linearity (non-linearity)	Departure from a straight line	0.1–0.5 % F.S.
Bias	Average indicated vs actual value	Same as accuracy (in practice)
Long-term stability	Output drift over years at constant input	Established by decades of case histories

The chapter's key insight for monitoring: change, not absolute value, is usually what matters — which makes precision more important than accuracy.

25.6–25.7 — Static vs dynamic; the instrument chain¶

Static monitoring dominates geotechnics (slow ground response), while dynamic monitoring covers earthquakes, blasting and machine vibration. Terminology is clarified along the chain: sensor → transducer → transmitter → instrument, a distinction the chapter uses consistently in later sections.

25.8 — Groundwater pressure (piezometers)¶

The chapter's longest instrument section, covering:

Casagrande standpipe piezometers — the simple, robust baseline.
Electric pressure transducers — VW and other types.
VW piezometer in a Casagrande standpipe — hybrid installation.
Zoned installation in a borehole — isolating a measurement zone with grout seals.
Push-in piezometers — rapid deployment where the ground permits.
Fully-grouted piezometers — the method (Contreras, Mikkelsen, McKenna, Vaughan, Penman references in the list) that has become standard for many embankment-dam installations.
Negative pore pressure / suction — the hardest measurement, with its own technique.

25.9 — Tilt and inclination¶

Tiltmeters — for structures and local tilt.
Inclinometers — the workhorse for lateral ground movement, read at fixed increments (e.g. 0.5 m / 2 ft) with probe-type systems.
In-place inclinometers and ShapeArrays — permanently installed profiles, with the chapter giving selection considerations for each (§25.9.3.1–25.9.3.2).

25.10 — Settlement, heave and differential settlement¶

Covered instruments: probe extensometers, borehole extensometers, liquid settlement cells, differential liquid settlement cells, and horizontal inclinometers — together spanning the range from surface settlement to deep heave.

25.11–25.14 — Cracks, strain/load, earth pressure, temperature¶

Crack and joint opening — crackmeters, jointmeters, soil extensometers.
Strain and load — strain gauges, load cells (concrete, steel, anchors).
Earth pressure — total pressure cells, push-in pressure cells.
Temperature — thermistors and thermistor strings (also the reference parameter for many other instruments' compensation).

25.15 — Automated data acquisition and telemetry¶

ADAS (Automated Data Acquisition Systems) are field-deployable devices that collect and store measurements from many sensors via cable or radio, and optionally transmit them to a remote computer without human intervention. Required features:

Signal management for mixed sensor types (VW, MEMS digital, 4–20 mA, 0–5/0–10 V analog, RS-485/SDI-12 digital).
Battery power (alkaline, lithium, or lead-acid + solar).
On-board data storage.
Low-throughput communications — radio, cell modem or satellite, on a schedule.
Optional local alarm/control.
A continuum from 1-channel standalone loggers to 1,000+ channel networks.

The chapter distinguishes a datalogger (one device carrying all/most features) from an ADAS (an elaborate logger that can also form a network, manage alarm conditions, and control external devices — SMS, valve actuation, siren/flashing light). Note the market trend: small loggers now carry features once found only in ADAS networks.

Small dataloggers (§25.15.1) — 1–10 channels, low power, "D"-cell 3.6 V batteries giving ≥1 year autonomy, operating range −40 °C to +80 °C, and increasingly a low-power licence-free radio (a few km in open terrain, ~1 km urban).

Integrated ADAS networks (§25.15.2) — two architectures:

Few central acquisition systems + long cable runs — drawbacks: cable cost, trenching/conduit, lightning-transient risk near the surface, added resistance, and splice-error risk. The chapter's recommendation is explicit: keep sensor cables short and add more acquisition points.
Hub-to-node radio networks using small radio-enabled loggers near the instruments — either a star configuration or a mesh network where loggers relay for each other to a gateway, then to the office by cellular, satellite, Wi-Fi or LAN.

25.16 — Software for data management, visualisation, alarming and reporting¶

Most loggers/ADAS emit delimited value files (*.csv, *.dat) with a timestamp column and one column per channel — often raw readings, which most users prefer to keep. Spreadsheets suffice for small jobs; larger or longer projects need dedicated software, which typically offers:

Dashboard (project overview, real-time values, sensors on alarm)
Real-time display with a colour code (Green: OK / Yellow: threshold / Red: alarm)
Trend lines (reading vs time, with scroll and zoom)
Alarm checking with automatic SMS/email
Virtual variables (calculated from one or more sensors)
Access controls (user profiles)
File converter (import from most logging systems, spreadsheets, manual records)
Correlation (XY) graphs (e.g. piezometric level vs rain; strain vs temperature)
Profile views (in-place inclinometers, ShapeArrays)
Automated reports on schedules
Smartphone/tablet visualisation and cloud hosting
Multi-language support
Import of geodetic (total station) and InSAR data
GIS / Google Earth geo-localisation

25.17 — Geodetic measurements¶

Ground-surveying methods detecting horizontal and vertical movement across a survey control network of monuments or on-structure points:

Total stations and levels — the core survey instruments; robotics, reflectorless and automatic target recognition enable automated operation. Typical accuracy: 1–5 arc-seconds in angle; 1–1.5 mm + 1–2 ppm in distance.
Rotating lasers — for alignment and grade.
Laser scanners — dense 3D capture (see Adamson et al., 2019, in the reference list).
GNSS — absolute positioning.
Satellite InSAR — comparison of repeat SAR images; X-, C- and L-band; pixel size 0.25–20 m (commonly 1–3 m), precision 1–20 mm; >50,000 points per km² over areas exceeding hundreds of km²; measurement along the radar beam (≈50–70° from horizontal), so true vertical displacement needs trigonometry; revisit a few days to 14+ days. Ascending+descending constellations add horizontal information.
Ground-based InSAR — terrestrial radar interferometry for local coverage.
UAV photogrammetry — aerial survey for deformation (see Stafford et al., 2019).

25.18–25.19 — Strong motion and vibration¶

Strong-motion accelerographs — 3D accelerometer + recorder, capturing peak particle acceleration (in g) and the time history. Best practice: one unit in the free field, plus one at the structure's highest point and intermediate positions, GPS-synchronised when multiple units are used. Classified A–D per USGS (2008) for the ANSS network; Canada operates the CNSN (100+ high-gain seismographs, 60+ accelerographs).
Vibration monitors — triaxial velocity sensor (geophone) + datalogger, measuring particle velocity in cm/s (blasting, traffic, ambient vibration — governed by the DIN 4150 series).

25.20 — Presentation of instrumentation data¶

The chapter's closing argument: all data must share a common timestamp, and that timestamp is the only link between monitoring data and construction activities (which unload and then reload the ground). Environmental factors — temperature and rainfall — must also be recorded, because unloading can open cracks that rainwater then exploits (Figure 25-23). Integrating monitoring data with construction activities and environmental factors remains a challenge for most commercial plotting programs — and any programme must allocate adequate resources so that data is presented and interpreted without ambiguity.

Key takeaways¶

Six parameters, one discipline. Groundwater pressure, displacement, strain, load, total pressure and temperature — each with its own instrument families.
§25.2 is the chapter's most reusable asset — a guided map of the standards (ASTM D18.23, ISO 18674, DIN 4150), textbooks (Dunnicliff, De Rubertis, Sharon & Eberhardt, Hoek), regulation manuals (USACE, Reclamation, FERC, ICOLD) and symposia behind monitoring practice.
Vibrating wire and MEMS dominate electrical measurement; fibre-optic sensing is the emerging third family.
Precision beats accuracy for monitoring, because change is what matters.
Keep sensor cables short and distribute acquisition — long surface runs invite lightning damage and splice errors.
Automation is a spectrum, from a 1-channel logger to a 1,000+ channel ADAS network with alarms and control.
Timestamp everything, and record temperature and rainfall — otherwise the data cannot be interpreted against construction activity.
Human factors decide success. The instrument–person marriage matters as much as the instrument.

Full reference list¶

Reproduced as the chapter's bibliography, for lookup. Standards are revised on their own cycles — verify the current edition.

Adamson, D., Alfaro, M., Blatz, J., Bannister, K. — Construction and Post-Construction Deformations of an MSE Wall using Terrestrial Laser Scanning. Geo St John's 2019, Canadian Geotechnical Society.

Anderson, C., Vessely, M., Christiansen, C., 2020 — Advances in Unstable Slope Instrumentation and Monitoring. TRB / NCHRP, National Academies, Washington DC.

Burland, J., Chapman, T., Skinner, H., Brown, M. (Eds), 2012 — ICE Manual of Geotechnical Engineering, Ch. 94 (Dunnicliff, Marr & Standing) and Ch. 95 (Dunnicliff). ICE Publishing, London.

Choquet, P., Juneau, F., Debreuille, P.J., Bessette, J., 1999 — Reliability, Long-term Stability and Gage Performance of Vibrating Wire Sensors with Reference to Case Histories. Proc. 5^th Int. Symp. on Field Measurements in Geomechanics, Singapore.

Choquet, P., Taylor, R.M., 2014 — Automatic Data Acquisition Systems (ADAS) for Dam and Levee Monitoring. Geo-Congress 2014, ASCE, 180–191.

Client guide to instrumentation and monitoring, 2017 — Chartered Institution of Civil Engineering Surveyors for the Survey Liaison Group, London.

Contreras, I.A., Grosser, A.T., VerStrate, R.H., 2007 — The use of the fully-grouted method for piezometer installation. Proc. 7^th Int. Symp. on Field Measurements in Geomechanics, Boston. (See also the 2008, 2011, 2012 and 2020 updates by the same authors.)

COSMOS, 2016 — Guidelines and General Considerations for Strong-Motion Instrumentation of Tall Buildings.

De Rubertis, K. (Ed.), 2018 — Monitoring Dam Performance — Instrumentation and Measurements, ASCE, 442 pp.

DIN — DIN 45669-1:1995; DIN 4150-1:2001; DIN 4150-2:1999 (under revision); DIN 4150-3:2016.

Dunnicliff, J., 1993 — Geotechnical Instrumentation for Monitoring Field Performance, Wiley, 577 pp.

Dunnicliff, J., 1994 — Contract Practices for Geotechnical Instrumentation. Geotechnical News, Vol. 12, No. 3.

Elwood, D.E.Y. & Martin, C.D., 2016 — Ground response of closely spaced twin tunnels constructed in heavily overconsolidated soils. Tunnelling and Underground Space Technology, 51, 226–237.

Ferretti, A., Monti-Guarnieri, A., Prati, C., Rocca, F., 2007 — InSAR Principles: Guidelines for SAR Interferometry Processing and Interpretation. ESA TM-19.

Glisic, B., Inaudi, D., 2007 — Fibre Optic Methods for Structural Health Monitoring, Wiley, 281 pp.

McKenna, G.T., 1995 — Grouted-in Installation of Piezometers in Boreholes. Canadian Geotechnical Journal 32, 355–363.

McRae, J.B., Simmonds, T., 1991 — Long-term Stability of Vibrating-wire Instruments: One Manufacturer's Perspective. Proc. 3^rd Int. Symp. on Field Measurements in Geomechanics, Vol. 1:283–293, Balkema.

Mikkelsen, P.E., 2002 — Cement-Bentonite Grout Backfill for Borehole Instruments. Geotechnical News, Vol. 20, No. 4, 38–42.

Mikkelsen, P.E. & Green, E.G., 2003 — Piezometers in Fully Grouted Boreholes. 6^th Int. Symp. on Field Measurements in Geomechanics, Oslo.

Pantony, B., Fraser, S., Sinacori, J., 2021 — Satellite InSAR for Geotechnical and Structural Monitoring. Canadian Geotechnique, Vol. 2, No. 1.

Penman, A.D.M., 2002 — Measurement of Pore Water Pressures in Embankment Dams. Geotechnical News, Vol. 20, No. 4, 43–49.

Pieraccini, M., Miccinesi, L., 2019 — Ground-Based Radar Interferometry: A Bibliographic Review. Remote Sensing 11(9).

Richards, D.J., Clark, J., Powrie, W., Heymann, G., 2007 — Performance of push-in pressure cells in overconsolidated clay. Geotechnical Engineering 160, GE1, 31–41.

Richards, D.J., Powrie, W., Roscoe, H., Clark, J., 2007 — Pore water pressure and horizontal stress changes during construction of a contiguous bored pile multi-propped retaining wall in Lower Cretaceous clays. Géotechnique 57(2), 197–205.

Ridley, A.M., 2015 — Soil suction — what it is and how to successfully measure it. 9^th Symp. on Field Measurements in Geomechanics, Australian Centre for Geomechanics, Perth, 27–46.

Schuyler, J.N. & Gularte, F., 2000 — Automated Tiltmeter Monitoring of Bridge Response to Compaction Grouting. SPIE 7^th Annual Int. Symp. on Smart Structures and Materials, Newport Beach, CA.

Sellers, J.B., 1994 — Load Cell Calibrations. Geotechnical News, Vol. 12, No. 3.

Sellers, J.B., Taylor, R., 2008 — MEMS Basics. Geotechnical News, Vol. 26, No. 1.

Sharon, R., Eberhardt, E. (Eds), 2020 — Guidelines for Slope Performance Monitoring, CSIRO Publishing / CRC Press, 331 pp.

Siskind, D.E., Stagg, M.S., Kopp, J.W., Dowding, C.H., 1980 — Structure Response and Damage by Ground Vibration from Mine Blasting. US Bureau of Mines RI 8507.

Soe Moe, K.W., Cruden, D.M., Martin, C.D., Lewycky, D., Lach, P.R., 2009 — Mechanisms and kinematics of river valley landslides in Edmonton. Annual Canadian Geotechnical Conference, GeoHalifax.

Stafford, D.M.J. et al., 2019 — Preliminary deformation detection of high-fill sections along the Inuvik-Tuktoyaktuk Highway using UAV photogrammetry. Geo St. John's 2019, CGS.

Stark, T.D., Oommen, T., Ning, Z., 2021 — Remote Sensing for Monitoring Embankments, Dams, and Slopes: Recent Advances, ASCE GSP 322, 114 pp.

Tedd, P., Powell, J.J., Charles, J.A., Uglow, I.M., 1990 — In situ measurement of earth pressures using push-in spade-shaped pressure cells — 10 years' experience. Geotechnical Instrumentation in Practice, Thomas Telford, London, 701–715.

U.S. Geological Survey, 2008 — Instrumentation Guidelines for the Advanced National Seismic System. Open-File Report 2008–1262, 48 pp.

Vaughan, P.R., 1969 — A Note on Sealing Piezometers in Boreholes. Géotechnique 19(3), 405–413.

Walker, J. & Awange, J.L., 2020 — Surveying for Civil and Mine Engineers, Springer, 411 pp.

Acknowledgement (original chapter). The chapter's author thanks the instrumentation suppliers who provided the figures and photographs for the original publication. Those figures are not reproduced here.