TASK 1
Design
Give a target degree of consolidation and a date. The tool searches the radius of influence and returns the spacing that meets it, for square and triangular patterns.
Prefabricated vertical drains
Drain spacing you can put your name on.
Design, simulate and back-analyse prefabricated vertical drains for the layered profile you actually have — and get a P10–P90 band you can defend, not one false-precision number.
- 1 · GroundEvery layer as it is, with smear?, vacuum, staging and creep?.
- 2 · TargetThe degree of consolidation you need, and the day you need it.
- 3 · AnswerThe spacing band, and a report you can issue.
A unit-cell? solver resolved in radius and depth, in your browser, beside the software you already use. Once built, calibrate it against your settlement plates and piezometers.
See a real report first — the worked Design example (PDF, 11 pages) →Sign-up opens with the public launch. Early-access accounts are set up by hand, with the example projects and the full user guide.
Slide 1 of 3 · The unit cell and a design result
ILLUSTRATIVE RUN · SQUARE100/100 met
Us = 90 % at t = 365 d
One run of the worked Design example. The sampling seed travels in the project file, so opening it and pressing Calculate returns these same three numbers.
- P10 · design basis
- 1,141 mm
- P50 · median
- 1,337 mm
- P90 · fast soil
- 1,609 mm
What it does not do. PVDCal solves consolidation in the unit cell around one drain. It does not assess slope or embankment stability, lateral spreading and deformation, or ground outside the treated area. Those remain separate analyses. The full list of limits.
01 — One soil model, three questions
Design, simulate, and learn from the field
The same solver runs in three directions, so a design and the back-analysis that later checks it share one set of physics.
TASK 2
Simulate
Give a spacing. The tool returns settlement and degree of consolidation against time, with the effective-stress profile and the compression path behind them.
TASK 3
Back-analysis & forecast
Give settlement plate and piezometer records. The tool calibrates the ground parameters that explain them, then forecasts the rest with a credible range.
02 — Video demo
A design run, start to finish
Two minutes, recorded in the application: the example project is opened, the target is typed, Calculate is pressed, and the spacing, the consolidation curve and the run summary are read. Nothing is staged.
The demonstration film was recorded with fresh random profile draws rather than a saved seed, so on-screen numbers differ slightly from take to take while a saved project reproduces its numbers exactly. The worked example in the user guide is the reference set.
Read the transcript instead ↓Hide the transcript ↑
- Open PVDCal in your browser. Project › Open › Example projects: three worked examples are built in.
- 1 · The design target. Type the degree of consolidation and the date it must be reached by.
- 2 · The drain and the pattern. Band-drain size, square or triangular grid, smear. In Design the spacing is the output.
- 3 · The soil profile. Each parameter can be a range; a range is what turns one answer into a band.
- 4 · The loading schedule. Construction stages, each placed over a ramp and then held.
- Calculate. 100 soil profiles are drawn from the ranges; each bar is one sample closing in on its spacing.
- Results. A menu of cards: spacing, consolidation curve, run summary, mesh, sensitivity.
- Drain spacing as P10 / P50 / P90. Square and triangular patterns, with the safe end marked.
- The consolidation curve. The band across all samples, and the time to reach the target.
- Format any axis. Bounds, scale, ticks, units and labels, per axis, on every chart.
- Export. Every chart downloads its data to Excel; Back-calculation also writes a Word report.
- The run summary. A written engineering report of the run: inputs, performance and recommendations.
- The mesh behind the numbers. Every run is a finite-volume solution on a grid you can inspect: drain, smear zone, layers.
- What moves the answer. One bar per input: which uncertainty is worth reducing first.
No sound track; the captions are part of the picture. Download the film (MP4, 8 MB).
03 — Real ground, not a chart
The complications design charts leave out
Charts assume one uniform layer, instantaneous loading and a constant coefficient of consolidation. Ground obliges none of that, so PVDCal carries each complication explicitly — and cites where it comes from.
Layered profiles
Every layer keeps its own compression indices, preconsolidation pressure, void ratio and permeability. Flux continuity is enforced at each interface.
Smear and transition zones
The disturbed annulus and the transition to intact soil are meshed explicitly, with mesh faces landing exactly on the zone boundaries.
Vacuum preloading
Suction enters as a wall value on the drain, with depth loss, and adds to the embankment schedule rather than replacing it.
Partially penetrating drains
Drains that stop short of the base are modelled as they are: the untreated layer keeps draining vertically, with a full-disk core below the tip.
Staged loading
Ramps, rest periods and multi-stage construction, with unload and reload following a recompression path rather than the virgin line.
Creep and stress dependence
Secondary compression through the Cα/Cc ratio, and a consolidation coefficient that follows effective stress instead of staying constant.
A smooth transition through yielding
The compression index is blended across the yielding zone rather than stepped at the preconsolidation pressure, because a natural deposit does not yield all at once.
A heat map of the whole cell
Play consolidation through the programme as an animated map of radius against depth, slice it at any depth or radius, and export it as an animation for your report.
04 — Where it fits
Between the design chart and the full FE model
Three ways to size a drain field. PVDCal takes the part the chart treats most coarsely and the finite-element model treats most expensively: the drain system itself.
CHART = design chart or spreadsheet · FE = full finite-element model
Soil profile
PVDCal
Any number of layers, each with its own parameters
CHART
One uniform layer
FE
Any number of layers
Smear zone
PVDCal
Smear and transition zones meshed explicitly
CHART
A single permeability ratio
FE
Modelled, if you build it
Loading
PVDCal
Staged, ramped, unload and reload, vacuum
CHART
Instantaneous
FE
Staged, if you build it
Consolidation coefficient
PVDCal
Follows effective stress and void ratio
CHART
Constant
FE
Depends on the constitutive model chosen
Answer
PVDCal
A P10 / P50 / P90 band from the parameter ranges
CHART
One number, read off a curve
FE
One number per run; bands need many runs
Learning from monitoring
PVDCal
Back-analysis of plates and piezometers, then a forecast
CHART
None
FE
Manual trial and error
Time to a result
PVDCal
About a minute per design; a back-analysis in under half an hour
CHART
Minutes
FE
Hours to days, including the model build
Outside the drain field
PVDCal
Not covered — by design
CHART
Not covered
FE
Stability, lateral movement, structures
Outside the treated area — differential settlement, stability, structures — the other tools remain the right ones. How the division of labour works →
05 — Back-analysis and forecast
Let the embankment tell you what the ground is
Feed in settlement plates and piezometers. PVDCal searches the parameter space for the soil that explains the record, reports how well it fits, and forecasts the remaining settlement with a credible range.
On the Ballina trial embankment in New South Wales — a published full-scale test on soft estuarine clay — the forecast from a 400-day record landed within 1.5 % of the final measured settlement, and within 0.8 % from a 700-day record.
- Forecast error from a 400-day record
- 1.5 %
- forecast error from a 400-day record
- Forecast error from a 700-day record
- 0.8 %
- forecast error from a 700-day record
06 — Who builds it
The person who answers is the person who wrote the solver
PVDCal is written and maintained by a practising geotechnical engineer and researcher whose work on the consolidation of PVD-improved clay is published in the peer-reviewed literature. GeotechLogic is a small software business in Victoria, Australia.
Try it on your own profile.
PVDCal is opening soon. Ask for early access and we will set you up with the example projects and the full user guide.