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.
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.
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.
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.
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.
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.
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.