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Settlement Monitoring

Hydrostatic level gauges across three measurement principles and three range bands — 0.01 mm resolution, ranges to 2000 mm — plus layered settlement gauges for subgrade consolidation, covering everything from routine foundation pits to precision engineering.

SCST 01/02 · RLS · HYDROSTATIC + MAGNETOSTRICTIVE

SCST hydrostatic level gauge with precision-machined chamber and tubing connectors

Overview

Sub-millimeter settlement, from one pit to a whole district

Hydrostatic leveling networks measure each point's settlement relative to a stable reference cell using the connected-vessel principle. SoilCreate offers three sensing principles — differential-pressure, magnetostrictive and ultrasonic — so the right physics is matched to each project's range and accuracy needs. On most structures they are deployed together with our tiltmeter series for a complete deformation picture.

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Three principles, three range bands
From 0–200 mm best-value monitoring to 0–2000 mm extra-large range and ultra-high-accuracy non-contact measurement.
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0.01 mm-class resolution
Resolves the slow, small settlements that decide whether a structure is safe — long before they are visible.
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RS485 to DAQ & cloud
Every gauge feeds the SoilCreate data loggers and Monitoring Cloud for automated, unattended operation.

0.01 mm

Resolution / Accuracy

0–2000 mm

Maximum Range

Measurement Principles

RS485

Bus Output

How it works

One Liquid Loop, One Stable Reference

Every gauge in the network is joined at the bottom by a liquid line and at the top by a separate air line, forming a system of communicating vessels: at rest, all liquid surfaces settle to one common level H₀. When monitoring point i settles, its sensor moves down relative to that shared surface and the liquid column above it grows — the cell reads ΔPᵢ = ρ·g·(H₀ − z_sensor,i), so settlement is sᵢ = (ΔPᵢ − ΔPᵢ,₀) / (ρ·g). The glycol working fluid (≈1050 kg/m³) carries a density temperature correction ρ(T) = ρ₀[1 − β(T − T₀)], β ≈ 4×10⁻⁴/°C.

Settlement of any point appears as a taller liquid column relative to the shared surface H₀ — which is why the reference cell sits on bedrock that must not move, and why liquid and air lines are routed separately. Until the reference is verified by periodic leveling surveys, every "settlement value" is relative, not absolute.

Everything is relative to the reference

Hydrostatic leveling outputs settlement relative to the reference cell. If the reference itself moves, the whole network drifts with it — so the reference goes on long-term stable bedrock and its own stability is re-verified by periodic leveling surveys. When all points drift in the same direction at once, suspect the reference first.

The magnetostrictive variant: absolute position

SCST02 reads its float magnet by time-of-flight on a magnetostrictive alloy waveguide (FeNi, TbDyFe): a microsecond current pulse meets the magnet ring's axial field, and the Wiedemann effect launches a torsional strain wave traveling at ≈2850 m/s toward a detection coil (inverse Wiedemann / Villari effect). Position is x = v·Δt — 100 ps timing resolves 0.3 µm, drift stays under 5 ppm/°C, and because position is absolute, the reading is retained through power loss.

Hydrostatic level gauges

Three Principles, One Family

Differential-pressure for best value, magnetostrictive for extra-large range, ultrasonic for the most demanding accuracy — together they cover the full spectrum of settlement projects.

Parameter	Differential-Pressure (SCST01)	Magnetostrictive (SCST02)	Ultrasonic
Principle	Connected-vessel differential pressure	Magnetostrictive time-of-flight, absolute position	Non-contact ultrasonic
Range	0–200 mm	0–2000 mm	approx. 100 mm
Resolution / accuracy	0.01 mm resolution	0.01 mm accuracy	Ultra-high accuracy
Output	RS485	RS485	RS485
Key strength	Best value for money	Extra-large range; reading retained on power loss	No contact with the liquid surface
Best for	Foundation-pit settlement	Large-area precision settlement: metro operation, building clusters	Precision engineering settlement

Engineered So the Data Can Be Trusted

Most hydrostatic-leveling failures happen at installation, not in the sensor. Our delivery process enforces the details that keep a network honest for years.

Independent liquid & air lines

Liquid and air tubes are always routed separately — sharing one conduit causes siphoning and silently invalidates the whole network. We never compromise on this.

Reference cell on stable ground

Every settlement value is relative to the reference cell, so it is installed on long-term stable bedrock and periodically re-verified by leveling surveys.

Temperature-corrected fluid

Readings carry a fluid-density temperature correction, and antifreeze concentration is re-checked on a 1–2 year cycle for cold-climate reliability.

Layered settlement gauge · RLS

See How Each Soil Layer Consolidates

Surface settlement tells you how much; layered settlement tells you where. Magnet rings embedded at target depths track each stratum independently — essential for subgrade filling, surcharge preloading and construction above shield tunnels.

1
Magnet rings anchored to the soil
Each ring is set at a target depth with opening claws that grip the surrounding stratum — so it moves with the soil, not with the access tube.
2
Manual probe reading
A reed-switch probe lowered down the access tube locates each ring to ±1 mm — a simple, economical routine for short-term construction monitoring.
3
Vibrating-wire automation
A vibrating-wire option upgrades resolution to 0.05 mm and removes site visits entirely — built for long-term, remote operation.
4
Layer-by-layer consolidation curves
Depth-resolved settlement time series show exactly which stratum is still consolidating — the evidence engineers need to release the next construction stage.

Dimension	Magnet-Ring Manual	Vibrating-Wire Automated
Accuracy	±1 mm	±0.05 mm
Site visits	Weekly readings	None — fully remote
Installation effort	Low	Moderate
Best for	Short-term construction	Long-term operation

Typical deployments: expressway subgrade, airport runways, surcharge-preloading programs and ground above shield-tunneling drives.

Selection guide

Settlement & Tilt: Pick the Right Product in One Glance

Settlement and tilt are usually monitored together on the same structure. This matrix covers both — tiltmeter details are on the Tiltmeter Series page.

Application Scenario	Recommended Product	Why
Foundation-pit settlement	Differential-Pressure Level Gauge (SCST01)	Best value for money
Large-area precision settlement	Magnetostrictive Level Gauge (SCST02)	Extra-large 0–2000 mm range
Precision engineering settlement	Ultrasonic Level Gauge	Ultra-high accuracy, non-contact
Layered subgrade consolidation	Layered Settlement Gauge (RLS)	Depth-resolved, layer-by-layer settlement
Dilapidated building / tower tilt	Wireless Tiltmeter (LoRa)	Cable-free deployment, long battery life
High-support formwork / tunnel	Wired Tiltmeter (RS485)	Higher accuracy, continuous acquisition
Bridge tilt monitoring	Wireless Tiltmeter (NB-IoT)	More reliable remote transmission

Installation

The Install Gates That Keep a Network Honest

None of these checks can be done at the factory — each one is confirmed on site, item by item, before the system goes live.

1
Keep every cell within range of the loop
Mount the reservoirs so height differences stay inside the sensor's range — beyond it, the differential-pressure output saturates.
2
Route liquid and air lines separately
Never share one PU conduit. A shared line creates a siphon: air squeezes the liquid column into interrupted flow and the whole network fails at once. This rule has no exceptions.
3
Put the reference cell on stable bedrock
All values are relative to the reference — install it on long-term stable bedrock and re-verify its stability with periodic leveling surveys.
4
Fill to level and purge air
Inject working fluid until every reservoir level is in place. A cell with trapped air bubbles reads erratically — re-bleed until the reading stabilizes.
5
Set the antifreeze verification cycle
Check or replenish antifreeze concentration every 1–2 years — concentration drifts with evaporation and refills, and an under-strength fluid freezes in cold climates. Check before winter, not after the first freeze.

Magnetostrictive cells: three boundaries

The magnet ring slides over the waveguide but must never touch it — contact damages the alloy waveguide and scraps the unit. Keep clear of welders, variable-frequency drives and heavy-current cables, and flag-and-exclude data logged during welding work. A single waveguide runs to 7.5 m at most; beyond that, switch to a segmented scheme. All three are confirmed at selection stage — discovering them on site usually means changing the model.

Layered settlement (RLS): set right before grouting

Pre-embed the access tube in the borehole at its design position. Slide each magnet ring over the outside of the tube with its claws opened to grip the surrounding stratum — an unanchored ring follows the casing, not the soil, and every "settlement" it reports is false. Record each ring's as-built depth against its stratum number before sealing the hole — a depth mismatch is the most fatal error in later data interpretation. On the vibrating-wire version, equalize the external spring pre-tension across points, or initial values carry a systematic offset into the whole history.

Gravity dam — hydropower settlement monitoring scenario — Dam & hydropower scenario — settlement networks alongside IPI and piezometers

Metro station platform — operation-period settlement monitoring scenario — Metro operation-period scenario — large-area precision settlement

High-rise construction site — foundation pit settlement monitoring scenario — Foundation-pit & building-cluster settlement scenario

FAQ

Field Questions, Straight Answers

Compiled from our after-sales records and the fault tables in the field manuals.

All points are drifting in the same direction — is the whole site settling?

More likely the reference cell itself is settling. Every value in the network is relative to it, so a moving reference drags all readings the same way. Re-verify the reference with a leveling survey and, if confirmed, re-select a stable reference location.

One point's reading keeps jumping around.

Air bubbles trapped in that cell. Re-bleed the cell until the reading stabilizes.

Readings respond sluggishly to known movement.

A blocked or over-bent liquid line. Clear the tube and ease the bend radius along the run. If a 4–20 mA channel reads exactly zero, check for reversed polarity or a broken wire with a multimeter.

What maintenance does the liquid loop need — especially in cold climates?

Verify or replenish antifreeze concentration on a 1–2 year cycle: concentration drifts with evaporation and refills, and an under-strength fluid freezes in winter. In cold regions, check before each winter rather than reacting to a freeze. Readings also carry the working fluid's density temperature correction.

Our magnetostrictive gauge jitters or spikes — is it broken?

Check the site log before suspecting the sensor. Sustained jitter points to strong electromagnetic interference — add shielding and re-route cabling away from welders and VFDs. A single spike usually coincides with welding or VFD transients: flag and exclude that period. No change at all suggests the magnet ring has detached; an outright invalid output means the waveguide is damaged and the unit is replaced as a whole.

A layered-settlement magnet ring suddenly shows a centimeter-level shift.

Don't alarm on a single reading. After rain, moisture in the probe can false-trigger the reed switch and mimic a sudden sink — dry the probe and re-measure. If an entire hole never moves, the casing is settling or the rings never gripped the soil: re-install. If a single ring reads in reverse, re-check the tape-cable depth markings. Re-measure first, check records second, conclude last.