Allgemein

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.

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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
• SANISAND-F
• SANISAND-MFs
• 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.…

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

In our latest paper published in 𝘊𝘰𝘮𝘱𝘶𝘵𝘦𝘳 𝘔𝘦𝘵𝘩𝘰𝘥𝘴 𝘪𝘯 𝘈𝘱𝘱𝘭𝘪𝘦𝘥 𝘔𝘦𝘤𝘩𝘢𝘯𝘪𝘤𝘴 𝘢𝘯𝘥 𝘌𝘯𝘨𝘪𝘯𝘦𝘦𝘳𝘪𝘯𝘨 (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 12^th: https://www.sciencedirect.com/science/article/pii/S0045782523005753?dgcid=coauthor

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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 12^th: https://authors.elsevier.com/a/1gdfi,63b-0MRi

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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 7^th: https://authors.elsevier.com/a/1gQ%7EbytxOTM4O

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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 Schmüdderich (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 30^th: https://authors.elsevier.com/c/1fuvT,63b~yZ2I

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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 (”Terzaghi”- and ”Butterfield”-version)
• Matsuoka-Nakai model (thanks to Christoph Schmüdderich!)
• 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…