# GTK-Field — Geotechnische Feldversuche

> Geotechnische Feldversuche (iPhone/iPad app by Matthias Kroell.)

- Source: https://appshunter.io/ios/app/gtk-field/id6760727960 (this page in markdown: same URL + `.md`)
- Developer: [Matthias Kroell](https://appshunter.io/developer/1885952457)
- Category: Utilities
- Price: Free
- Age rating: 4+
- Requires: iOS 15.0 · 5 MB
- Languages: American English
- Released: 2026-03-27
- Data updated: 2026-07-23
- User reviews in markdown: https://appshunter.io/ios/app/gtk-field/id6760727960/reviews.md

## What is GTK?

GTK-Field is the professional field documentation app for geotechnical engineers in Austria, Germany and Switzerland. All investigations are documented according to European standards - directly on site, paperless and efficient.

INCLUDED MODULES

TEST PIT (Schuerfgrube)
Soil layer classification according to EN 14688-1/2 with 30+ soil types, BGR colours and hatching patterns. Dual-chip system for admixtures with intensity and grain fraction. True-to-scale layer profile in PDF.

GENERAL SITE OBSERVATION
Field observation with GPS positioning, photo documentation and standardised PDF report.

DYNAMIC PROBING (Rammsondierung)
Dynamic probing according to EN ISO 22476-2. Supports DPL, DPM, DPH and DPSH. N10 values are displayed live with colour coding (green / yellow / red) and exported as a complete PDF report with resistance diagram.

INFILTRATION TEST (Versickerungsversuch)
Determine kf-values directly in the field - standpipe test according to OENORM B 4422-2 (falling head, constant head, base infiltration) or pit infiltration test with simple and extended kf-calculation. Automatic evaluation using the Hvorslev method, drawdown curve and soil classification according to DIN 18130-1.

SAMPLE COLLECTION
Document soil samples by category A, B and C. Container management, laboratory status tracking (Pending - Submitted - Evaluated) and PDF report.

PDF EXPORT
All modules export standardised PDF reports including company logo, GPS coordinates, date, inspector and optional photo appendix - instantly shareable via email or AirDrop.

KEY FEATURES
- 100% offline - no internet connection required
- Automatic GPS positioning via iPhone
- Camera integration for photo documentation
- All data stored locally on device
- Cloud synchronisation via Supabase (optional)

Developed by GTK-Geotechnik Kroell ZT GmbH, Schmirn/Austria - by geotechnical engineers, for geotechnical engineers.
Questions or feedback: office@geotechnik-kroell.com


## Version history (last 5 releases)

### 1.5.0 — 2026-07-10

Troubleshooting

### 1.4.0 — 2026-07-08

Version 1.4.0 brings more flexible reports and many improvements:
• Site inspection: signer can now be selected per inspection, company name is taken automatically from the settings
• Sample data now available for all test types, including infiltration test and sieve analysis, try any module with realistic data in one tap
• The active project is now clearly marked in the project list
• PDF: consistent, cleanly formatted footers in all reports, improved text wrapping in the inspection report
• Reliability: protection against duplicate report creation, numerous minor fixes
Feedback welcome at matthias@geotechnik-kroell.com

### 1.3.0 — 2026-06-18

What's new in version 1.3.0:

- New module: Sieve analysis per DIN/OENORM EN ISO 3310 with automatic soil classification according to EN ISO 14688-2, grain size distribution curve and uniformity coefficients (Cu/Cc)

- Dynamic probing: Redesigned N10 chart with trend line (moving average) and color-coded bars for improved readability

- Improved trial pit profile display: Layers are shown proportionally to their thickness, with better page layout in the PDF reports

- Added legal notice regarding calculated and estimated values, accessible anytime in the settings

- Various layout and stability improvements in the PDF reports across all investigation types

### 1.2.4 — 2026-06-07

Version 1.2.3 – German Standards Profile (DIN)
New: Each project can now be switched between the Austrian (ONORM) and German (DIN) standards profile. A toggle in the project view automatically updates all PDF protocols – norm references in headers and footers adjust accordingly.
New for the DIN profile: Four infiltration test methods are available per DIN 18130-2 and DWA-A 138-1 – Open-End Test (borehole), borehole refill test, test pit refill test, and double-ring infiltrometer. The double-ring infiltrometer is fully supported with dedicated geometry inputs (inner and outer diameter, insertion depth) and circular-area-based kf calculation.
Existing projects automatically retain the Austrian standards profile.

### 1.2.2 — 2026-06-02

Version 1.2.2

· Test pit PDF: depth values now correctly displayed with two decimal places (e.g. 0.00 m – 1.30 m)
· Test pit PDF: groundwater level now only shown in the correct soil layer
· Test pit PDF: groundwater depth in the header now shows depth below ground surface
· All PDFs: decimal numbers consistently formatted with comma separator
· Infiltration test: drawdown curve now displayed compactly on page 1, saving one page
· Bugfix: decimal inputs using comma notation (e.g. 1,80 m) are now saved correctly

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*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-07-23.*