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Item type:Publication, Access status: without files , Numerical analysis of quay walls under high-cyclic loading(2026-08-17); ; ; Numerical analysis of quay walls under high-cyclic loading. Validated numerical models for predicting long-term deformations of port infrastructure under high-cyclic loading are still limited in availability. In particular, the numerical representation of soil-structure interaction of quay walls subjected to cyclic loading has received little attention to date. This paper presents a methodology and its limitations for the inverse identification of constitutive parameters that are often difficult to determine in practice, as well as for the long-term prediction of cyclically loaded quay walls. Using the Athabaska quay wall as a case study, two-dimensional finite element analyses are performed in PLAXIS. The subsoil is modelled using a hypoplastic constitutive model with intergranular strain and the HCA model. The constitutive parameters are identified inversely by coupling numerical simulations with particle swarm optimisation (PSO). Measured horizontal quay wall displacements from 1996 and 2024 are used for comparison. With R2 = 0.92, the results show very good agreement between the simulations and the measurements. 50-year prognostic analyses show deformations of up to 10.3 cm and a declining deformation rate toward the end of the considered period. Overall, the coupling of numerical simulations with optimisation algorithms provides a transferable approach for the assessment of existing quay walls.Publicationtype: Journal Article3 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Zum geregelten Vibrieren von Profilen in den Boden(Ernst & Sohn, 2026-04-23); ; ; On controlled vibratory driving into the soil. Vibratory installation of profiles is established practice and, compared with impact driving, often offers advantages in installation time as well as reduced noise and vibration emissions. In practice, the key machine parameters (e.g., frequency, static eccentric moment, and, if applicable, static load) are still largely selected based on experience, although the installation process represents a complex, soil-dependent multi-objective problem. This paper consolidates research on cost-effective, tolerance-compliant profile installation. It presents developments in vibrators and experimental setups for sensor-based process monitoring, optimization criteria, and control approaches for adapting operating parameters. A focus is placed on processes at the profile toe in saturated soil during so-called cavitational driving. Numerical studies (CFD-DEM, SPH) and an instrumented test rig show that the upward motion can cause a pronounced drop in pore water pressure and local liquefaction of the soil beneath the profile toe, explaining the high process efficiency and indicating pathways to improve bearing capacity. In addition, data-driven methods (Dynamic Mode Decomposition) for short-term prediction of ground vibrations as a component of real-time monitoring and control are discussed. Finally, an outlook is given on the DFG project DROPS, which investigates downward forces as well as stiffness requirements of profiles and driving guides to meet installation tolerances.Publicationtype: Journal Article12 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Zur Modellwahl bei geotechnischen Randwertproblemen – Beispiele und kritische AnmerkungenModel selection for geotechnical boundary value problems – examples and critical remarks. Numerical methods are widely employed in both research and practice to model boundary value problems. In conjunction with observations and measurements, they facilitate a deeper understanding of mechanical processes at the micro and macro scales. At the microscale, the interactions between particles, pore water, and gas are of particular interest. Here, the application of computed tomography is unlocking a new realm for soil mechanics. While numerical models for this scale are, to some extent, still under development, the combination of imaging and modelling enables an enhanced understanding of these fundamental processes. At the macro-scale, dynamic and time-dependent soil-structure interaction problems present particular challenges. The installation of structures typically induces large soil deformations and associated changes in the soil state, necessitating the use of specialized numerical techniques. Furthermore, cyclic loading leads to the accumulation of deformations, which limits the serviceability of the structure over time. These phenomena will be demonstrated through examples, followed by the formulation of critical remarks.Publicationtype: Journal Article12 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Numerische Untersuchungen zur Definition von KastenfangedämmenNumerical investigations for the definition of box-type cofferdams. Cofferdams in cell and box form serve as temporary structures for enclosing large excavation pits or as permanent structures for bank reinforcements and breakwaters. Box cofferdams consist of two mutually anchored and parallel sheet pile walls, with fill material in between. Box cofferdams are often subjected to unilateral loads and are designed to withstand large horizontal forces such as water pressures, impact loads, or earth pressures. The recommendations of the Working Committee on Bank Reinforcements [1] provide guidelines for the design of cofferdams, primarily based on the studies by [2]. In the stability verification of box cofferdams, according to [1], it is assumed that a compact soil block exists between the opposing cofferdam walls. However, [1] does not explicitly define when two opposing walls are considered a box cofferdam structure. To define the applicability ranges for box cofferdams, extensive numerical investigations in the serviceability state were carried out for this article.Publicationtype: Journal Article13 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Zur numerischen Berechnung der globalen Standsicherheit von Bauwerken im Boden(2022-09); ; ; For the numerical calculation of the stability of structures in soil. The use of the finite element method (FEM) for the design and recalculation of geotechnical structures is steadily increasing. For both slopes and retaining walls, the advantages of the FEM are already used for accurate determination of the deformations and stresses of structures in the serviceability limit state (SLS). The application in the ultimate limit state (ULS) is currently still a research topic for structures with soil-structure interaction, such as retaining walls. An extended strength reduction, where component strength is reduced in addition to the shear parameters of the soil, is intended to account for the influence of the structure in ULS-simulations. In addition to the component strength, other parameters, such as the external load-bearing capacity of anchors or the contact friction between soil and component, play a role for determination of the governing failure mechanism. Using a Python script, the strength reduction approach implemented in PLAXIS 2D is re-implemented and verified exemplarily on a braced excavation pit and a tie-back quay wall. By extending the own strength reduction implementation with additional parameters, which are relevant for the stability of geotechnical structures, their influence on the stability calculation and the resulting failure mechanisms is investigated.Publicationtype: Journal Article37 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Zur Tragfähigkeit von granularen Lastverteilungsschichten über StabilisierungssäulenApproach to determine ultimate stress mobilization in the Interface of rigid inclusion head and load transfer platform. One field of application for rigid inclusions is the soil improvement for large-area structures such as (fibre-) reinforced slabs of logistics centers and other complexes. To optimise the slab (thickness and reinforcement), a load transfer platform (LTP) is usually installed above the columns. The aim of the LTP is to decouple the rigid inclusions from the structure and to enable a shallow foundation design of the slab. The interaction between columns, LTP and slab must be taken into account, which can cause additional stresses in the LTP and in the slab. In this paper, the approach proposed by french ASIRI recommendation for a granular LTP over rigid inclusions is presented, considering the conventional failure mechanism according to German standard DIN 4017. In a parameter study, influencing variables on the limit state of the LTP be evaluated. In addition, the results of FE calculations on an axisymmetric unit cell with a stiffness reduction of the surrounding soil are used. The FE calculations show that the allowable limit stress increase with a reduction of the LTP thickness, but up to the critical height additional bending moments in the slab must be taken into account. The bending moment increases with a reduction of the LTP thickness.Publicationtype: Journal Article150 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Messtechnische Begleitung der Einbringung einer Tragbohle mittels Vibration und Schlagrammung(2020-06-01); Measurement monitoring of the installation of a king pile with vibration and impact ramming. The installation of combined sheet steel pile walls is still a challenge. Distorted king piles can lead to a failure in the connection between the king pile and the sheet pile. There is only little of rules how to choose the driving hammer and guiding which is suitable for the soil and installed pile. Currently the proof for combined walls is only done for the final state. Hence a proof for the combined walls is required which takes the installation process in account and a guideline for choosing the correct guiding for the installation of king piles is required. Unfortunately, the dynamics of the installation process of king piles is not well known. That's why the installation of a big king pile is investigated on a construction site at the harbor of Rostock. It's possible to measure the acceleration, change in length and inclination at the king pile. Further the dynamics and movements of the installation devices, which are influenced by the ram guide, can be investigated. The following change in the position of the foot of the king pile can be derived.Publicationtype: Journal Article110 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Evaluation of clogging and wear of tools in loose rock based on model tests(2019-06); ; Evaluation of clogging and wear of tools in loose rock based on model tests. The occurrence of clogging of the cutting wheel and in the mixing chamber as well as the wear of cutting tools still represent a problem in mechanized tunneling with earth pressure balanced shield drives (EPB) and hydroshield drives. Despite different procedures for prognosis based on the plasticity and consistency indices, still massive delays of tunnel excavation occur due to clogging because interruptions are needed for cleaning of the cutting wheel and the mixing chamber. Besides the clogging problems, also abrasiveness of the subsoil frequently represents a problem, because strongly abrasive soil leads to the frequent need for changing the cutting tools. A correct assessment of clogging potential as well as of abrasiveness, especially in loose rock and mixed soils still represents a difficult task for the employer and his ideally all-embracing request for bids as well as for the contractor who has to consider the clogging potential and abrasiveness as exactly as possible in his offer. In this contribution, a new cutting wheel model test is presented, which is, in contrast to existing methods, supposed to consider the interaction of human influence, machine and subsoil in a harmonic way for the prognosis of clogging problems and problems of cutting tool wear in mechanized tunneling.Publicationtype: Journal Article127 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Zur Anwendung von Einplatinen-Computern in der bodenmechanischen Forschung und Lehre am Beispiel eines einaxialen Druckversuchs zur Untersuchung teilgesättigter, granularer Böden(2019-03-01)On the application of single-board computers in soil mechanical research and teaching using the example of an uniaxial compression test for the investigation of unsaturated granular soils. For some years, single-board computers and microcontrollers are increasingly applied in circles of hobbyists, in teaching at schools and universities, but also in industry and science. In this contribution, it is demonstrated, how a soil mechanical testing apparatus is developed and built, based on a practical experimental measurement project from soil mechanics research on unsaturated granular soils. The contribution focuses on the application of single-board computers in soil mechanics research and teaching. Here, different benefits can be found, e. g., from the point of view of research, the liberty of developing new experimental apparatuses, and from the point of view of teaching, the motivation to acquaint students of soil mechanics with laboratory measurement technique and (physical) programming, a domain of civil engineering studies that rather misses out, or that is rather approached very cautiously by students despite its growing importance.Publicationtype: Journal Article136 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Zum besonderen Quellverhalten von Tarrastonen(2018-12); ; ; About the extraordinary swelling behaviour of Tarras Clay. In the course of the currently ongoing variant analysis for a new fixed link across the Fehmarnsund Tarras Clay has been found at various depths. Just like 50 years ago, it presents a serious challenge to the construction measures. Especially the shrinkage and swelling behaviour of the clay as well as its very low shear strength in the area of slickensided discontinuities may cause serious problems with regard to a new bridge or tunnel construction. This article compares the composition, the microstructure and the swelling behaviour of different soil samples that were classified as pure Tarras Clay in order to point out correlations. For instance, it was shown that no reliable statement can be made about the swelling behaviour based on the grading curve of the examined clay samples. However, plasticity index and water absorbency represent much more reliable indicators. Two clay samples were tested, whose granulometric composition, clay mineralogy and settlement behaviour were almost the same, but their swelling properties were found to be very different. In this article the reasons are discussed and the microstructure of Tarras Clay is analysed in greater detail. Furthermore, the test results are compared to literature values of better researched London Clay.Publicationtype: Journal Article126