About
A geotechnical engineering practice that builds its own tools
GeotechLogic is a small geotechnical software business based in Victoria, Australia. PVDCal is its first product: the ground-improvement solver its founder wanted on every soft-clay project, made available to other engineers.
Who builds it
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. The physics in the solver is the physics in those papers, and the validation figures are the ones a reviewer would ask for. The business is a sole practice, so the person who answers your message is the person who wrote the code.
Where it lives
GeotechLogic is an Australian business operating under Australian Consumer Law and the laws of Victoria. Your account and your data are held in Sydney, Australia; your project files stay on your own computer. Payments are handled by Paddle, the Merchant of Record, so PVDCal never sees your card.
Provenance
Why you can put your name on the number
Software that produces a figure for a report has to be attributable. Here is what stands behind PVDCal, with a link to each piece of evidence.
The method is published
The consolidation model behind PVDCal, a stress-dependent permeability and compressibility formulation for PVD-improved clay, was published in the peer-reviewed geotechnical literature in 2015 and has been cited and used since. The numerical scheme that solves it, a cell-centred finite-volume method in radius and depth, is described in full in the Numerical Method chapter of the user guide.
Read the method page →The solver is checked against closed-form solutions, inside the app
Eight benchmarks — Olson–Barron, Hansbo with and without smear, Terzaghi, Carrillo, vacuum, partial penetration and the layered stack — run from the About menu of the application itself, on the same code that produces your results. The mean absolute error is at most 0.53 percentage points of the degree of consolidation.
See the benchmark table →The back-analysis is tested on a real embankment
The Ballina trial embankment in New South Wales, a published full-scale test on soft estuarine clay with settlement plates and piezometers, is used as the field check. Calibrated on the first 400 days, the forecast of final settlement was 1.5 % away from the measured value; on 700 days, 0.8 %.
See the Ballina case →Everything is written down
A 249-page user guide covers every card, every equation and every validation figure, and it is free to download without an account. If the guide and the application ever disagree, that is a bug we want to hear about.
Download the user guide →Scope
What PVDCal is, and what it is not
It is a unit-cell solver for prefabricated vertical drains: one drain, the soil cylinder it serves, resolved in radius and depth. It is meant to sit beside your existing software, not to replace it.
It does
Drain spacing for a target, settlement and consolidation against time, uncertainty bands, and back-analysis of settlement plates and piezometers, all for the drain system itself.
It does not
Stability, lateral displacement, differential settlement across block edges, structures, or anything outside the treated area. Those stay with your three-dimensional and finite-element tools.
Your responsibility
PVDCal is an engineering aid. The inputs, the interpretation and the design decision remain with the engineer who signs, as the terms say plainly.
Questions about the company or the method?
Write to us. Messages are answered by the engineer who builds PVDCal, normally within two working days.