New paper: Long-term settlement of dynamically loaded shallow foundations

Together with Dirk Wegener from GEPRO Ingenieurgesellschaft mbH (Dresden), we present an extension of conventional analytical settlement analyses that takes into account the accumulation of deformations due to cyclic loads with high frequencies, as they occur for example for machine foundations or railway tracks. The incorporation of a threshold strain amplitude, below which no accumulation of deformations occurs, in the HCA model is discussed. It is demonstrated that the simple analytical approach, which does not require numerical calculations, gives results very similar to more complex finite-element simulations performed with numgeo.

Find the authors’ version here and the journal publication here.

New numgeo release

We have once again released a new numgeo version, with many new features, a new html documentation, a “portable” numgeo version without additional software requirements and new examples.

Some specific new features:

  • Stabilized u-p elements with equal order interpolation
  • Improved numerical stability in infiltration processes
  • HCA model for clay available in the public version
  • Explicit dynamic analyses

The html documentation contains the full release notes.…

Workshop at TU Dresden

The first numgeo workshop took place on the 24th and 25th of January at the Institute of Geotechnics at TU Dresden. The focus was on the introduction to the various possibilities of the FE software and the simulation of different boundary value problems. The participants from the universities (TU Dresden, BTU Cottbus and Prof. von Wolffersdorff) as well as from practice used numgeo for the simulation of high-cyclically loaded foundations, for infiltration processes, for problems of soil dynamics and soil liquefaction as well as for the simulation of vibratory pile driving. In addition to the application, many technical discussions were held on the implementations in numgeo.

We would like to thank Prof. Herle for the invitation to the TU Dresden, the joint exchange on numerical geotechnics and the opportunity to present numgeo.

New paper: Validation and calibration of a hypoplastic model for expansive soils

The numerical modeling of swelling strain and swelling pressure of expansive soils when saturated with a unique set of material parameters is still a challenge that persists to this day. In collaboration with BTU Cottbus and Ruhr University Bochum, we have developed a new hypoplastic model for expansive soils. In our latest publication in the journal Bautechnik, we validate this model by back-calculating numerous laboratory tests and introduce a simplified calibration procedure.

New paper: Contributions to numerical modelling of geotechnical boundary value problems โ€“ automatic parameter calibration, earthquake-induced liquefaction and pull-out resistance of grouted anchors

In our latest paper in Bautechnik, we address two challenging topics: the automatic calibration of advanced constitutive models and the significance of the constitutive contact model in realistically simulating soil-structure interaction.

Automatic Calibration & Slopes under Seismic Loading:

We demonstrate the robustness and applicability of numgeo-ACT, a software for automatic calibration of soil mechanical material models for both monotonic and cyclic loading. Using the example of a water-saturated dam under seismic loading, we showcase both its robustness and its excellent predictive capability.

Pull-out Resistance of Grouted Anchors:

What impact does the choice of the constitutive contact model have on the predicted anchor pull-out resistance? Our investigations show that a simple Coulomb friction model cannot capture important components of the load-bearing mechanism. In contrast, the hypoplastic contact model implemented in numgeo leads to significantly better predictions.

New paper: Separating fluid and solid contact constraints for hydro-mechanically coupled finite elements discretising fluid displacement

Left: Deformed configuration of the solid phase during pile driving and field of effective horizontal stress.
Right: Deformed configuration of the fluid phase
During uplift of the pile, only the fluid phase follows the pile, while the solid phase separates from the pile tip

How to model the interface between a structure and a saturated porous medium?

In our latest paper published in ๐˜Š๐˜ฐ๐˜ฎ๐˜ฑ๐˜ถ๐˜ต๐˜ฆ๐˜ณ ๐˜”๐˜ฆ๐˜ต๐˜ฉ๐˜ฐ๐˜ฅ๐˜ด ๐˜ช๐˜ฏ ๐˜ˆ๐˜ฑ๐˜ฑ๐˜ญ๐˜ช๐˜ฆ๐˜ฅ ๐˜”๐˜ฆ๐˜ค๐˜ฉ๐˜ข๐˜ฏ๐˜ช๐˜ค๐˜ด ๐˜ข๐˜ฏ๐˜ฅ ๐˜Œ๐˜ฏ๐˜จ๐˜ช๐˜ฏ๐˜ฆ๐˜ฆ๐˜ณ๐˜ช๐˜ฏ๐˜จ (CMAME) we present a mortar contact discretization scheme enforcing contact constraints separately for the pore fluid and the solid.

Back-calculation of vibratory pile driving tests shows that the proposed scheme increases both numerical stability as well as predictive capabilities of the simulation compared to contact methods not distinguishing between contact constraints for the solid phase and the fluid phase.

Free access to the paper until November 12th:

New paper: A theory of porous media for unsaturated soils with immobile air

In most works, unsaturated soil is considered a three-phase medium composed of air, water, and solid, neglecting effects caused by the presence of residual water and/or entrapped (immobile) air.

We present a set of governing equations for unsaturated soils with residual water and entrapped air considering a mass transfer mechanism between the free air and the entrapped air. The performance of the model is examined in simulations of water retention curves, a rapid drawdown experiment as well as in the dynamic analysis of a centrifuge test on a dam subjected to earthquake loading.

Free access to the paper until April 12th:,63b-0MRi

New paper: Deep vibratory compaction

Determining the achieved densification by deep vibratory compaction is a challenging task, both practically and numerically.

In the framework of a DFG Project (German Research Council) and in cooperation with Keller Grundbau we have developed an efficient numerical scheme to estimate the effects of deep vibratory compaction using numgeo. A paper describing the approach has now been published in Soil Dynamics and Earthquake Engineering.

Free access to the paper until March 7th:

New paper: Factor of Safety for slopes subjected to earthquake loading

How to determine a Factor of Safety of water-saturated slopes under earthquake loading accounting for material-induced failure and the role of pore-fluids? Not an everyday question, but all the more challenging for it.

Together with Christoph Schmรผdderich (corresponding author), Felipe Prada and Torsten Wichtmann we present an extended strain-dependent slope stability concept by Nitzsche and Herle (2020) which allows advanced constitutive models to be included in the analysis. Tolerable computation times are achieved by using machine learning algorithms.

Free access to the paper until November 30th:,63b~yZ2I

New numgeo release

We have now released a new numgeo version, with plenty of new features, bugfixes and new examples.

In particular, we have added

  • an example for a 3D monopile simulation using the HCA model and
  • examples for infiltration problems using the 3-phase elements in numgeo.
  • a simulation of a 3D pile with comparison of the results to a commercial code

Some specific new features:

  • Compliant base boundary conditions
  • Including external files in input file
  • AVISA-2022 (thanks to Merita Tafili!)
  • Karlsruhe hydraulic model (soil water retention curve accounting for void ratio dependence and scanning curves)
  • Modified Cam-Clay (โ€Terzaghiโ€- and โ€Butterfieldโ€-version)
  • Matsuoka-Nakai model (thanks to Christoph Schmรผdderich!)
  • Support of (arbitrary) user-defined external solvers
  • Variable bishop effective stress parameter

The keyword reference manual contains a list of bugs we have resolved since the initial release…