Principle and application
A settlement plate is a steel plate placed at the base of the embankment, on the natural ground, before the first layers are placed. A rod protected by a casing rises from it and is extended with each new layer. Levelling the top of the rod measures the settlement of the foundation over time.
For embankments on soft clay, consolidation settlement can take months or years and reach metres. The settlement versus time curve shows how far consolidation has progressed, allows the final settlement to be estimated (for example, with the Asaoka method) and guides decisions such as the rate of fill placement, when to remove the surcharge and when to start paving.
Typical applications: highway and railway embankments on soft soil, bridge approach fills, port and industrial yards, fills with vertical drains and surcharge, and foundations of tanks and stockpiles.
Installation step by step
Layout
Plates are set out at the control sections, usually on the centreline and edges of the embankment, and placed on the levelled natural ground.
Installation and zero reading
The plate receives the rod and the protective casing, which isolates the rod from friction with the fill. The initial reading is taken before any load is applied.
Extension
With each layer, rod and casing are extended, and the top is levelled before and after the splice so the reference is never lost.
Levelling
Readings by precise levelling from benchmarks installed outside the zone of influence of the embankment.
Analysis
Settlement versus time and fill height versus time curves, settlement rate and estimate of the final settlement.
Quality controls: stable benchmarks checked periodically, precise levelling with closure within tolerance, splices levelled before and after, physical protection of the rods against equipment traffic and a record of fill height at each reading.
According to DNER-PRO 381
| Standard | DNER-PRO 381/98 (design of embankments on soft soils for transport works, Brazil) |
|---|---|
| Surveying | ABNT NBR 13133 (topographic surveying) |
| Technical reference | Almeida, M. S. S.; Marques, M. E. S. Aterros sobre Solos Moles: projeto e desempenho (Oficina de Textos, 2010); Dunnicliff, J. Geotechnical Instrumentation for Monitoring Field Performance (Wiley, 1993) |
| Measured quantity | Vertical settlement at the base of the embankment |
| Reading method | Precise levelling from stable benchmarks |
| Frequency | Follows the pace of fill placement: more frequent while layers are placed and less frequent during consolidation |
| Deliverable | Plate as-built, reading sheets, settlement versus time and fill height versus time curves, settlement rate, final settlement estimate and report |
Carried out to the same QA/QC, HSE and site standards as every Damasco Penna service, described in Quality and field operations.
Frequently asked questions about Settlement Plates
What is a settlement plate used for?
To measure the settlement of an embankment foundation over time. The settlement curve shows how much the soft soil has already consolidated and how much is still to come, which guides the pace of construction.
Why monitor settlement during construction?
Because consolidation of soft clay is slow and actual settlement often differs from the design prediction. Measuring it makes it possible to adjust the rate of fill placement, decide when to remove the surcharge and avoid paving too early.
Settlement plate or piezometer?
Both. The plate shows deformation and the piezometer shows the dissipation of pore pressure; read together, they confirm the progress of consolidation and the safety of the embankment.
How long does monitoring last?
From the first layer until settlement stabilises, which can take from a few months to years, depending on the clay thickness and the use of vertical drains.
Related services
Settlement Plates for your project
Tell us about the project and we will put together the monitoring plan and the quote.