Search

Pile foundations frequently endure dynamic loads, necessitating an in‐depth examination of the cyclic shear properties at the pile–soil interface. This study involved a series of cyclic direct shear (CDS) tests conducted on sand and concrete with irregular surface, utilizing varying displacement amplitudes (1, 3, 6, and 10 mm) and joint roughness coefficients (0.4, 5.8, 9.5, 12.8, and 16.7). Discrete Element Method (DEM) models, informed by experimental data, facilitated mesoscopic mechanical response analyses. Findings indicate that the sand–concrete interface undergoes softening, with hysteresis loops' morphology dependent largely on displacement amplitude. A maximum ultimate shear stress corresponds to a specific critical surface roughness, while the initial tangent modulus escalates with increased concrete roughness. Volume variations of the specimen inversely correlate with displacement amplitude and directly with surface roughness. As displacement amplitude expands, there is a reduction in the maximum shear stiffness and an elevation in the maximum damping ratio. Empirical formulas for the surface roughness and normalized shear stiffness were proposed. Larger displacement amplitudes result in more substantial shear bands and heightened energy dissipation, yet the incremental energy ratio remains largely unaffected. Predominant energy dissipation mechanisms include both slip and rolling slip, with the former surpassing the latter in energy dissipation capacity. The anisotropy directions of contact normal, normal contact forces, and tangential contact forces consistently fluctuate with shear direction alterations. [ABSTRACT FROM AUTHOR]

This study introduces an innovative approach to improving speaking proficiency among Korean EFL learners through the use of vlogs, further evaluating their impact on learners' foreign language speaking anxiety (FLSA) and willingness to communicate (WTC). In this semester‐long experiment, 49 university students were divided into an experimental group (n = 25) and a control group (n = 24). The former engaged in vlogging activities, while the latter received traditional instruction devoid of social networking. Data were collected via pre‐ and post‐questionnaires on FLSA and WTC, coupled with pre‐ and posttests assessing speaking skills. Vlogging significantly decreased FLSA and bolstered WTC in Korean EFL learners, demonstrating a marked improvement when contrasted with the control group. Additionally, the experimental group, engaged in vlogging, displayed superior advancement in vocabulary, comprehension, fluency and task proficiency. However, no discernible enhancements were observed in speaking accuracy when compared to the control group. With the evidence of reduced anxiety, increased communication willingness and enhanced speaking proficiency in the vlogging group, this study provides a concrete foundation for EFL teachers to consider integrating vlogging and similar social media‐based activities into language instruction. This approach could contribute to creating more engaging and comfortable learning environments, aiding learners in overcoming affective barriers and improving their language skills. Practitioner notesWhat is already known about this topic Prior research in second language acquisition probed the impact of social media on diverse language learning areas: vocabulary, intercultural learning, speaking skills, pronunciation and writing skills.Social media‐integrated language learning demonstrated potential in enhancing oral proficiency among English as a Foreign Language (EFL) learners.Limited research exists exploring the influence of social media, especially vlogging, on EFL learners' speaking skills and affective factors such as Willingness to Communicate (WTC) and speaking anxiety.What this paper adds This study demonstrates that a learning environment cultivated via social media, particularly vlogging, improves speaking proficiency and positively influences affective factors like Foreign Language Speaking Anxiety (FLSA) and WTC.The findings suggest that social media‐integrated speaking activities, specifically vlogging, offer a beneficial and effective pedagogical strategy to ameliorate speaking proficiency, FLSA, and WTC in supportive and non‐intimidating contexts.Implications for practice and/or policy This study offers crucial insights for EFL teachers planning courses to enhance speaking proficiency:The integration of vlogging and similar social media‐based activities into language instruction is strongly supported by the evidence of reduced anxiety, increased communication willingness and enhanced speaking proficiency in the vlogging group. This study provides a concrete foundation for such innovative approaches.The creation of an engaging, interactive and stress‐free learning environment is essential, enabling learners to practice speaking English without anxiety. This approach can also aid learners in overcoming affective barriers and enhancing their language skills.EFL educators should prioritize improving key attitudinal factors, such as anxiety and WTC. These factors significantly contribute to the holistic development of oral proficiency.When incorporating social media‐based speaking activities like vlogging, teachers' targeted feedback on recurring learner mistakes can foster improvements in speaking accuracy.EFL teachers must recognize their critical role in nurturing a supportive, non‐intimidating environment, paving the way for learners to effectively enhance their speaking proficiency. [ABSTRACT FROM AUTHOR]

This article provides a comprehensive overview of the activities of the Working Group 2.1 "Piles" of the German Society for Geotechnics (DGGT) in 2023. The group focused on the calculation and design of piles, particularly in relation to the second generation of Eurocode 7. They also worked on national mirror committees for relevant European execution standards and international standards for pile testing. The article discusses the progress and challenges of finalizing Part 3 of Eurocode 7, which includes piled foundations. It also highlights the expansion of the chapter on piled foundations in EN 1997-3 to cover new aspects such as the design of pile groups and combined pile-raft foundations. The text emphasizes the importance of referring to the relevant standards for accurate and up-to-date information on pile execution and testing. Ongoing research on the influence of groundwater flow on cast-in-place concrete piles and the significance of adequate concrete cover during pile construction is also mentioned. The working group is open to input and suggestions from colleagues in the field and plans to develop a new chapter on the design of combined pile-raft foundations and the design of piles under seismic loads. [Extracted from the article]

Basic and detail design of the Ruhr‐ und Harborcanal bridge in Duisburg The Oberbürgermeister Karl Lehr bridgesection in Duisburg is one of the four Ruhr crossings and has an overarching function for urban traffic and in particular for the industrial location around the port of Duisburg. As a result of the increased load from general traffic and freight traffic from the port, the bridge turned into a bottleneck. In order to cope with the increasing traffic load and increase its capacity, the existing traffic areas of the bridges needed to be expanded. A basic overhaul and extension of the existing, partly very old bridge structures, was ruled out due to their design and structural condition. Therefore, all structures along the bridge section will be replaced by new structures in the same position. This article explains the key aspects of the design and execution planning of the Ruhr and Harborcanal bridges, provides insights into the structural implementation and provides compact information about the overall project. [ABSTRACT FROM AUTHOR]

Optimization of void formers in reinforced concrete slabs for arbitrary combinations of internal forces The use of void formers in reinforced concrete slabs makes an important contribution to reducing greenhouse gas emissions in the construction industry. While the flexural strength of reinforced concrete slabs is generally not changed by the hollow bodies, the shear strength is reduced compared to a solid slab. The advantages of structures with void formers can be further exploited through optimized void former shapes, whose geometry is designed in such a way that the possible reduction of concrete volume is maximized and the reduction of load‐bearing capacity is minimized. This paper describes a method for optimizing the volume displacement of void formers for any given combination of bending moments and shear forces. A genetic algorithm is used in combination with nonlinear FEM simulations. The results of 39 optimization runs with different combinations of internal forces are presented and the effects of the bending moments and shear forces on the possible volume reduction are worked out. The inversely proportional relationship between volume reduction and shear strength is shown. The practical benefit is shown in the form of an application example for a foundation slab with optimized void formers arranged according to the stress, thus minimizing the total volume of concrete used. [ABSTRACT FROM AUTHOR]

Due to the installation of energy piles, the surrounding soil will be inevitably disturbed, leading to a smaller void ratio and larger thermal conductivity. This study proposes a new closed‐form solution to calculate the heat exchange of energy pile foundations considering smear effects on the different soil thermal properties in the smear zone and undisturbed zone. The analytical model adopts the separation of variables to solve the governing equations. The eigenvalues are obtained according to a series of recurrence formulas and a transcendental equation. The solution is verified against existing analytical solutions in literature and numerical simulation, and an excellent agreement is obtained. The parametric study shows that a larger thermal conductivity of the soil in the smear zone results in a lower temperature at any given time. If the smear effects are not considered, the temperature will be overpredicted, especially for the pile and the soil in the smear zone. The proposed solution precisely predicts the soil temperature in the smear zone and undisturbed zone, which can contribute to the thermo‐mechanical behaviour of energy pile foundations in further work. [ABSTRACT FROM AUTHOR]

Due to the installation of energy piles, the surrounding soil will be inevitably disturbed, leading to a smaller void ratio and larger thermal conductivity. This study proposes a new closed‐form solution to calculate the heat exchange of energy pile foundations considering smear effects on the different soil thermal properties in the smear zone and undisturbed zone. The analytical model adopts the separation of variables to solve the governing equations. The eigenvalues are obtained according to a series of recurrence formulas and a transcendental equation. The solution is verified against existing analytical solutions in literature and numerical simulation, and an excellent agreement is obtained. The parametric study shows that a larger thermal conductivity of the soil in the smear zone results in a lower temperature at any given time. If the smear effects are not considered, the temperature will be overpredicted, especially for the pile and the soil in the smear zone. The proposed solution precisely predicts the soil temperature in the smear zone and undisturbed zone, which can contribute to the thermo‐mechanical behaviour of energy pile foundations in further work. [ABSTRACT FROM AUTHOR]

The city of Gothenburg in western Sweden is currently experiencing the construction of one of the biggest infrastructure projects in the country – The West Link (Västlänken). The West Link is an 8 km double‐track railway project, of which 6 km will be through underground tunnels with two new stations, Haga and Korsvägen, and construction of a bigger Central station. The construction of the project began in May 2018 and the finalization is expected in 2026. The project is split into five different sections which were awarded and are being executed individually. The widely varied geological profile of the area consisting of weak‐to‐very weak clay and silty‐sandy‐gravelly moraine along with challenging local conditions like existing waterways, traffic routes, and buildings requires a range of soil improvements and shoring system solutions suiting the local conditions. Some techniques executed by Keller include dry deep soil mixing (DDSM) to stabilize the quick clay to facilitate excavation, jet grouting for water sealing, excavation support in addition to soil improvement purposes, uplift piles over a flowing river, drilled steel piles at the bottom of excavation pit as foundation support, drilled steel pile wall, and sheet piling. Apart from technical challenges, the West Link has strong focus on adopting sustainable solutions like methods to reduce disposal of wet masses from jet grouting. A team of experts of design and execution from different parts of the world is working together to make it a success story. [ABSTRACT FROM AUTHOR]

The demolition of old bridges and the construction of new bridges are obviously not as good as retaining old bridges through the transformation in a short period of time. To continue using the old bridge and implement the new bridge and the old bridge at the same elevation, the old bridge overall jacking of 2.57 m is the only feasible plan (Figure 2). The old bridge in the middle is retained and still used, and the new bridge on both sides is adopted to broaden the bridge. [Extracted from the article]

Hydraulic heave in round excavation pits with relief boreholes – calculation approach The use of relief boreholes to reduce the effect of a vertical upward flow has proven to be a constructive measure to avoid the risk of hydraulic heave in excavation pits in groundwater. The applicable standards and regulations, however, only provide general information on the use of relief boreholes. A concept for the verification against hydraulic heave failure using relief boreholes is missing as well as defined information on the arrangement of the relief boreholes and the influence of the excavation geometry. Therefore, the aim of the research work at the Chair of Geotechnical Engineering of RWTH Aachen University was to develop a concept for the proof against hydraulic heave failure with the arrangement of relief boreholes. The result was a calculation approach that determines the decisive fracture body under consideration of the flow conditions due to the relief boreholes. This fracture body can then be used for the proof against hydraulic heave failure. Based on this, dimensioning diagrams were finally generated for typical excavation pit geometries in dimensionless representation. [ABSTRACT FROM AUTHOR]

The temporary bridges over the Ahr A devastating flood in the Ahr valley in July 2021 claimed 134 lives and caused massive damage to the infrastructure, including bridges. The flood wave was caused by a combination of factors, including heavy rainfall, a large catchment area, saturated soils, narrow valleys, and slate slopes. The numerous bridge structures partially acted as a temporary dam, which eventually failed and was washed away under the pressure of water and debris, causing the already flood‐like flow of the Ahr river to accumulate into a flood wave. Around 60 bridges were destroyed, and in the town of Bad Neuenahr‐Ahrweiler alone, 23 out of 25 bridges were destroyed. In order to quickly provide helpful solutions for the affected citizens, some temporary bridges had to be erected to bridge the planning and construction time for new permanent structures. This article reports on these temporary bridges and their construction. [ABSTRACT FROM AUTHOR]

Role allocation during the development, update and utilisation of the specialized model subsoil – Recommendation No. 4 of the working group 2.14 (DGGT) "Digitalization in geotechnical engineering" Regarding the classical workflow in civil engineering, the responsibilities between geotechnical engineers, the client and other project partners like technical planners and construction companies are clearly defined and well established. In infrastructure construction, however, it will be prospectively obligatory that the geotechnical expert delivers a specialized model subsoil in addition to the geotechnical report. As this specialized model subsoil needs to be directly interconnected with other specialized models to build up the overall BIM model, the geotechnical expert will most likely be deeper embedded in the planning and construction process over the whole project life cycle. Furthermore, due to the need of standardization in the BIM process and the need to develop a suitable model structure for all specialized models, the client will also gain further responsibilities compared to the classical planning process. As an example, the clients have to define a clear and explicit model structure for the geotechnically related specialized models, too. This leads to an expansion as well as adaption of responsibilities throughout the project handling. Within this fourth recommendation of the DGGT working group 2.14 "digitalization in geotechnical engineering" the existing organizational structures within BIM projects are described and the responsibilities are defined focusing on the development of the specialized model subsoil. [ABSTRACT FROM AUTHOR]

This article is a summary of the available research works of cast‐in‐place deep‐seated bored piles in Myanmar. Instrumented static pile load test results are analyzed, discussed, and updated. The information contained in the article is mainly from the construction projects of private sectors constructed in Yangon and extended study of previous work on current practices of deep foundations and deep excavation Works in Myanmar. [ABSTRACT FROM AUTHOR]

The sand‐filled nodular pile (SFNP) foundation is newly proposed to improve the bearing capacity and accelerate consolidation settlement of foundations installed in soft clay soil. By filling sand while driving the nodular pile into the soft clay soil, the SFNP foundation provides an extra drainage path with the aid of the nodular segment, while maintaining the high modulus reinforcement body at the core of the composite foundation. The performance of the SFNP foundation is greatly influenced by its consolidation behaviour. This study develops a generalized model for the SFNP foundation, and a closed‐form solution is then established considering the smear and well resistance effects. The developed model and the associated analytical solution are employed to investigate the consolidation rate and load distribution of the SFNP foundation. Finally, the analytical solution is utilized to evaluate the performance of SFNP foundation for an expressway project located in Zhejiang, China. The predicted dissipation of the excess pore water pressure employing the developed analytical solution agreed well with measured response from the field test, which further confirmed the advantages of the SFNP foundation and the reliability of the developed solution. [ABSTRACT FROM AUTHOR]

Introduction: The Australasian Teletrial Model was piloted in co‐funded sites across Australia. The purpose was to extend the reach of clinical trials using telemedicine to improve equity and access to this treatment pathway for oncology patients. Experts across Australia gathered to share the learnings of implementation so that future directions can be effective and sustainable. Methods: The 1‐day workshop was attended in person and virtually. Attendees were invited to analyze and disseminate the results. Recordings from the presentations were coded independently by three researchers and synthesized. The results were sent to the authorship team for further review to build consensus on the findings in three drafts. Results: Four key themes were identified: "Being on the Same Page," "Building Foundations," "Key Roles in Teletrials," and "Incentives." Although there were many successes that were accelerated by the COVID‐19 pandemic, there is work still to be done. Conclusion: The Australasian Teletrial Model has been identified as acceptable and feasible. Future directions need to continue to work on streamlining regulatory processes, implementation and monitoring, and build knowledge to further build networks across Australia. [ABSTRACT FROM AUTHOR]

S21 PfA 1.3a – construction planning of the airport connection The construction project "S21 airport connection PfA 1.3a" is part of the major project Stuttgart–Wendlingen–Ulm and includes about 5 km of the high‐speed line along the A8 motorway as well as the connection to Stuttgart Airport. The construction work includes, among other things, 1.4 km of troughs and tunnels in open construction, 3.5 km of tunnels in mining construction, twelve bridges and culvert structures as well as the incision and dam structures of the new line. With the execution of the excavation pits as well as the special foundation engineering work, numerous interfaces to the civil engineering, the railway construction and the existing structures are created. In the transition area between tunnels in open construction and mining construction, complex combined pit systems with ground anchors, rock nailing, bracings and "Totmann" constructions result due to the construction process. The railway line is based on the backfilling and the engineering structures of the troughs and tunnels in open construction. The challenging task in the production of the piles for the foundation of the railway overpass on the B312 was the immediate proximity of the foundation piles to the existing trough. The transfer of horizontal bedding forces to the trough is prevented by the creation of an annular gap between the foundation pile and the subsoil. Essentially, the following report will reflect the planning of the excavation pits and the associated interfaces within the framework of the S21 PfA 1.3a airport tunnel project. For this purpose, a holistic view of the execution planning is required. [ABSTRACT FROM AUTHOR]

In many major rock projects, services have spanned decades or even hundreds of years. For engineering design, it is necessary not only to ensure the safety of personnel during construction but also to ensure the safety of long‐term use and operation in the future. Therefore, it is indispensable to study the creep damage mechanical properties of rocks before the construction of the project. For a long time, rock creep has been an important reason for large deformation and even instability in building foundations, underground tunnels, and slopes. Moreover, the surrounding rock generally exhibits obvious creep damage characteristics under an environment of high stress, high temperature, and high water‐pressure. Under certain geological conditions, this creep damage behavior is extremely prominent. Therefore, the study of rock creep damage mechanics is very important. This paper reviews the advancement of rock creep damage mechanics from the aspects of mechanisms, research methods, constitutive models, and so forth. Rock creep is a process of interaction between structural damage and the hardening effect. The structural damage and hardening effect are opposite to each other, but they exist in the same physical process. The creep research method introduces mainly the research objects, influencing factors, monitoring methods, and experimental methods. Creep constitutive models introduce mainly empirical models, linear element combination models, nonlinear combination models, and other nonlinear models based on new theory. Finally, based on the current research progress, several important research directions in rock creep damage mechanics are pointed out. Highlights: The rock creep and damage mechanism is analyzed.The creep experimental methods are summarized.The research progress of the creep constitutive models is discussed.Several important research directions in rock creep mechanics are pointed out. [ABSTRACT FROM AUTHOR]

This paper is mainly concerned with the development and design of a reduced order model in numerical simulation of the unsteady temperature field of the stadium building foundation in frozen areas, based the finite element (FE) method and proper orthogonal decomposition (POD) with the snapshot technique. We first derive the standard FE formulation of the unsteady temperature field and compute its FE full solutions, from which we choose a few spatio‐temporal solutions as snapshots. Based on POD technique, we then build a set of optimal POD bases maximizing the energy content in the original ensemble data, and in the new space spanned by the POD basis, we establish a low‐order numerical model of reduced‐order finite element (ROFE) formulation of the unsteady temperature field. And we prove the error estimates of the ROFE solutions of the unsteady temperature field. Finally, numerical tests are provided to simulate the temperature field of crushed stone clay under the natural pavement near the foundation of a stadium building in a frozen soil area of the northwest of Sichuan province in China. [ABSTRACT FROM AUTHOR]

Tiwag – Tiroler Wasserkraft AG sees itself as a driving force in the energy transition, pursuing the goals of the Tyrolean and Austrian energy strategies with a moderate, environment friendly expansion of hydropower. The projects are essentially aimed at expanding existing power plants so that they can be used more effectively, and additional hydropower potential can be developed. The Kirchbichl Power Plant is a good case in point. From 2017 to 2020, the power plant was made fit for the next decades as part of an extensive refurbishment and expansion project. The main project components are to improve flood security through the construction of an additional weir field, to adapt to enhanced environmental standards through the construction of a fish passage and a power plant for residual flow, and to increase the discharge of the power plant by installing an additional turbine. One of the challenges was the construction pits in the immediate vicinity of the existing system. The pit design with bored pile retaining wall and base seal with a jet grout slab has proven to be very effective. [ABSTRACT FROM AUTHOR]

A newly developed design concept for plane earthwork structures on pile foundations is presented. This design concept is based on a complex mathematical background that has been derived using fundamental mechanical principles. The mechanical system comprises the arching effect in a plane earthwork structure on punctual supports. It incorporates the effect of an elastic membrane that is formed by orthogonal ribs of geogrids, the modulus of subgrade reaction between the piles and the elastic settling of the piles. Some practical design examples are shown. The important aspects of the analysis and the design are pointed out. The complete mathematical background and a comprehensive design tool for free use have been prepared and are provided through a download link: https://gft‐pes.blogspot.com. [ABSTRACT FROM AUTHOR]

Challenges in foundations for high‐rise buildings in glacially preloaded soils The economical and safe design of foundations for high‐rise buildings in Berlin requires a realistic assessment of the expected settlements for both the building itself as well as for existing neighboring structures. In this context taking account of glacial preloading and the corresponding increase of soil stiffness has a significant impact on the quality of the settlement prediction. In this paper different approaches to derive soil stiffness parameters are compared with regard to settlement measurements at various buildings in Berlin. It can be shown that stiffness values based on the correlations of EC 7‐2 significantly underestimate the in‐situ stiffness of the soil types encountered in Berlin. A more realistic reproduction of soil stiffness is possible with the stiffness values of TEV Gesteinseigenschaften and a stiffness approach developed by the authors. In these approaches soil density respectively soil consistency as well as the geological history of the soil layers with regard to glacial preloading are taken into account. [ABSTRACT FROM AUTHOR]

Evaluation of software for the creation of soil models In the "Road Map for Digital Design and Construction" of the Federal Ministry of Transport and Digital Infrastructure (BMVI), public infrastructure projects are required to use the Building Information Modeling (BIM) method. As a result, the Federal Department of Foundation Engineering of the Federation of the German Construction Industry (Hauptverband der Deutschen Bauindustrie e. V.) demands a discipline‐specific model for foundation soil from the client in its technical position paper. The discipline‐specific model should consist of the earth's surface in the form of a digital terrain model (DTM), the soil layer model and also the subsoil data on which it is based (drillings, survey data, etc.), as well as layer information and soil characteristics of the subsoil on the basis of the geotechnical report. The location of the layer boundaries between the outcrops is to be derived by using interpolation methods and adjusted by manual post‐processing. In order to manage these challenges, different software is evaluated. [ABSTRACT FROM AUTHOR]

Foundation strengthening/new foundations to the historically sensitive structure of the Pergamon Museum on the Museum Island in central Berlin. The three‐wing building for the presentation of mostly large classical objects was built between 1910 and 1936 and after 100 years requires thorough refurbishment. In order to regain complete museum functionality and provide the correct climatic conditions for the exhibited objects, extensive strengthening measures, new foundations and lowering of the basement inverts are unavoidable. The extensive archived documents showed that the Pergamon Museum is founded at several levels at a depth of between 6 and 18 m below ground level. The deep geological scouring in the foundation formation led to great problems with the planned raft foundation after soil exchange under the protection of dewatering. The available results of the soil survey from 1912 in the area of the south wing, which until then had been built over, showed that the organic scouring extended down to about –12 m below sea level. This demanded a fundamental alteration of the foundation in this building section. Neither the dewatering plant nor the deep foundation elements available in 1912 were capable of reaching the loadbearing ground about 45 m below ground level. The stringent requirements for the deformation behaviour of the existing structures and in particular the south wing of the Pergamon Museum, which remained in use during the refurbishment works, required appropriate monitoring of reactions, which had to be constantly compared during the construction works. Both vibration and settlement curves were recorded and used as a decisive criterion for the selection of possible refurbishment technologies from specialised civil engineering. The solutions selected on site, both in the completion phase and in the current refurbishment phase, are described and discussed in this article. [ABSTRACT FROM AUTHOR]

Abstract: Cities are often seen as centres of economic growth, providing opportunities for study, innovation and employment. An increasing part of the European Union population lives and works in cities and it is widely expected that these patterns will continue as urban areas account for a greater share of activity. This asks for high rise buildings and advanced foundations systems, which are able to transfer high loads from the ground surface into deeper layers. In this contribution we focused on the design optimisation of combined piled raft foundations (CPRF) under uncertainty of load and resistances. We developed a novel optimization algorithm considering the uncertainty of load and resistance parameters. This innovative scheme is applied to an illustrative case study of a combined piled raft foundation in order to show the strength of the proposed approach. [ABSTRACT FROM AUTHOR]

As part of the Stuttgart 21 infrastructure project, German Railways is building a four-line railway bridge across the River Neckar in Stuttgart, work started in 2016. The Neckar railway bridge has an overall length of 345 m and has two abutments and six support axes. The structure crosses rail lines from the urban transit (Stadtbahn), the main trunk road B 10, inner city roads, the Neckar River, pedestrian and cycle ways as well as diverse public and private utilities. The bridge structure is located within the core mineral water protection zone, with its strict restrictions regarding the permissible depth of penetration into the subsoil and groundwater reservoirs. The mineral water springs lie within the construction site 26 m below the surface as artesian aquifers with an artesian pressure of ca. 10 m above ground level. From a groundwater management perspective, and following a program of five ground investigations and their evaluation, a raft foundation at the mid-level of the lower Keuper, built using cut-and-cover technique with a compressed air caisson, was chosen as the most economical foundation type for the three primary supports. A further programme of hydrochemical and geomechanical ground investigations was undertaken during the construction design phase. Following an evaluation of these additional ground parameters, it was possible to replace the compressed air caisson with a more economical deep foundation using large diameter piles. A management concept for possible scenarios was needed for the large diameter pile construction to achieve the required consent for exceptions from the ban on ground penetration in the area of the mineral springs. [ABSTRACT FROM AUTHOR]

About the influence of one-way loading on the bearing be haviour of precast concrete piles for onshore wind energy plants. Due to the energy transition several wind energy plants are built. Precast impact driven concrete piles represent one option to realise foundation piles onshore. In Germany, the bearing capacity of these piles can be estimated using empirical values taken from current standards or using in-house specifications of plant producers. Cyclic loading of such foundations exceeding 20 % of the static characteristic pile bearing capacity have to be considered when estimating the pile bearing capacity. However, the consequences of cyclic loading for the bearing behaviour of precast impact driven concrete piles are not fully understood yet. Therefore, field tests in cohesive and non-cohesive soils considering static and cyclic loading with different load amplitudes have been conducted and are presented within this paper. Using prevalent methods stated in current standards to estimate the bearing capacity of piles under static and cyclic loading are applied to recalculate the results of the field tests. Thereby, the suitability of these methods for estimation of the bearing behaviour of precast impact driven concrete piles under static and cyclic loading is reviewed. [ABSTRACT FROM AUTHOR]

An investigation is made to present analytical solutions provided by a Winkler model approach for analysis of piled rafts with nodular pile subjected to vertical loads in nonhomogeneous soils. The vertical stiffness coefficient along a piled raft with the nodular pile in nonhomogeneous soils is derived from the displacement given by the Mindlin solution for elastic continuum analysis. The vertical stiffness coefficients for the bases of the raft and the nodular part in the nodular pile in a soil are expressed by the Muki solution for the 3-D elastic analysis. The relationship between settlement and vertical load on the pile base is presented considering the Mindlin solution and the equivalent thickness in the equivalent elastic method. The interaction factor between the shaft of the nodular pile and the soil is expressed taking into account the Mindlin solution and the equivalent elastic modulus. The relationship between settlement and vertical load for a piled raft with the nodular pile in nonhomogeneous soils is obtained by using the recurrence equation of influence factors of the pile for each layer. The percentage of each load carried by both nodular pile and raft subjected to vertical load is represented through the vertical influence factors proposed here. Comparison of the results calculated by the present method for piled rafts with nodular piles in nonhomogeneous soils has shown good agreement with those obtained from the finite element method and a field test. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In real conditions, decision makers usually deal with multiple objectives and should make a decision in a state of certainty or uncertainty. The selection of the best constructions for a building from a number of alternatives is of great importance for owners, contractors, and stakeholders. Dozens of multicriteria/multi-attribute decision-making (MCDM/MADM) models developed for evaluating the performance of the available alternatives can be used for selecting the most suitable alternative from a given finite set of options based on a set of attributes. A guide to systematic selection among the available alternatives of building structures is the integrated methodology, thoroughly analyzed in the article. The article presents a MCDM model for selecting the type of foundation for a single-storey dwelling house based on the WASPAS-G (Weighted Aggregated Sum Product Assessment) method and Analytic Hierarchy Process (AHP) approach. The aggregate criteria weights are determined by using the AHP and experts' judgement methods. [ABSTRACT FROM AUTHOR]

Due to the low tensile strength of masonry perpendicular to the bed joint, masonry wall panels have non-linear material properties. Assuming simple elastic constitutive laws, this article presents two modelling variants, which consider the lack of tensile strength in a simple manner. Both variants are investigated for their advantages and disadvantages. In a second part of the article, the application of the methods will be illustrated through the example of a four-storey building. [ABSTRACT FROM AUTHOR]

This paper advocates the use of a multiphase model, already developed for static or quasi-static geotechnical engineering problems, for simulating the behaviour of piled raft foundations subject to horizontal as well as rocking dynamic solicitations. It is shown that such a model, implemented in a FEM code, yields appropriate predictions for the foundation impedance characteristics, provided that shear and bending effects in the piles are taken into account, thus corroborating the findings of the asymptotic homogenization theory. Besides, it is notably pointed out that such a multiphase-based computational tool makes it possible to assess the dynamic behaviour of pile groups in a much quicker way than when using direct numerical simulations, which may face oversized problems when large pile groups are concerned. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This article is written against the backdrop of the work of the European standardisation committees on the amendment of EN 1996-1-1 [N 4] which will also exert an influence on the design of reinforced masonry in Germany. This paper focusses on the design approaches of DIN EN 1996-1-1 for untensioned reinforced masonry beams under shear load in the ultimate limit state (ULS). Proposals are made to discuss their revision. The contents of E DIN 1053-3 [N 3] and of the final draft of the guideline 'Flat Lintels' [7] are taken into account. [ABSTRACT FROM AUTHOR]

This article deals with the production of veneer walls as specified in DIN EN 1996-2/NA [3]. Against this background of the extensive revision of the section for veneer walls an exposition in accordance with the previous requirements as specified in DIN 1053-1 can hardly be recommended. The necessity for a basic revision of the section for veneer wall construction has already been discussed in detail and justified in several technical articles published in previous years, see [4] to [7]. With many changes and corrections in the section for veneer walls in the National Annex of DIN EN 1996-2 [8] it is certainly not a question of new rules for this method of building, but an adjustment of the requirements in the previous standard on the basis of the practical experience gained over several years. The new requirements for the execution of cavity facing masonry enable a simple and economic implementation of this external wall construction. [ABSTRACT FROM AUTHOR]

In the recent past, the masonry industry has developed many different solutions for optimising the heat protection of buildings. This took place for the building materials, geometric design, but also by development of multiple layered stones in which the components masonry unit, insulation and outer shell have been integrated into a block. [ABSTRACT FROM AUTHOR]

The loadbearing capacity of steel-concrete composite slabs using thin-walled steel sheeting with prepressed embossments is in most cases determined by their resistance in longitudinal shear. The design of composite slabs still requires full-scale laboratory bending tests to be performed. Small-scale shear tests cannot include all of the influences affecting the bent slab. However, by using an appropriate procedure, the shear characteristics obtained from such tests can be used to determine the bending capacity of the slab. Two such procedures are compared in this paper. End restraints effectively increase the loadbearing capacity of the composite slabs. Two different types of easily assembled additional end constraints are also tested and compared in this paper. Small-scale tests are used to obtain their shear bearing characteristics and to predict the loadbearing capacity of bent slabs using these restraints. [ABSTRACT FROM AUTHOR]

The undrained bearing capacity of a group of three rigidly connected skirted foundations (tripod) under vertical, moment or combined vertical-moment loading is investigated. Three-dimensional displacement finite element analyses of a single footing are first presented in order to validate the numerical modelling procedure. Various loading paths are considered and comparisons with known solutions are made. Subsequently, a series of analyses of undrained loading on a three-footing group is presented. Different footing spacings and loading directions are considered. The predominant failure mechanisms for characteristic load combinations are determined and the calculated failure loads are presented in dimensionless and normalized form. Based on the numerical results, a unique normalized failure load surface is proposed which applies to all loading directions and footing spacings for a given skirt length to footing diameter ratio. Undränierte Grenztragfähigkeit von Tripod-Gründungen mit Schürze unter außermittiger Belastung. Die undränierte Grenztragfähigkeit einer Gruppe von drei starr miteinander verbundenen Gründungselementen (Tripods) unter Vertikallast, Momentenbelastung oder unter einer kombinierten Vertikal- und Momentenbelastung wird untersucht. Zunächst werden dreidimensionale Finite-Elemente-Berechnungen von einem einzelnen Gründungskörper präsentiert, um die numerische Modellierung zu validieren. Unterschiedliche Belastungspfade werden untersucht und mit bekannten Lösungen verglichen. Anschließend wird eine Reihe von undränierten Analysen mit allen drei Gründungskörpern eines Tripods vorgestellt. Variiert werden die Fundamentabstände und die Lastrichtung. Die vorherrschenden Versagensmechanismen werden für charakteristische Lastkombinationen bestimmt und die berechneten Grenztraglasten in dimensionsloser und normierter Form dargestellt. Basierend auf den numerischen Ergebnissen wird eine einzige normierte Grenzzustandskurve vorgeschlagen, welche auf alle Lastrichtungen und Fundamentabstände für ein gegebenes Verhältnis von Schürzenlänge zu Durchmesser der Gründungskörper anwendbar ist. [ABSTRACT FROM AUTHOR]

The present study pertains to the development of a foundation model for predicting the behavior of geosynthetic reinforcement railway track system rested on soft clay subgrade. The ballast and sub-ballast layers have been idealized by Pasternak shear layer. The geosynthetic layer is represented by a stretched rough elastic membrane. Burger model has been used to characterize the soft clay subgrade. Numerical solutions have been obtained by adopting the finite difference scheme combined with non-dimensioning the governing equations of the proposed model. The results confirm that the present model is quite capable of predicting the time-dependent settlement response of geosynthetic reinforcement railway track system placed on soft clay subgrade. The surface settlement profile and mobilized tensile load of geosynthetics has been evaluated by considering variation in the wheel load, sleeper width, thickness of ballast and sub-ballast layers and shear modulus of ballast and sub-ballast layers. It has been observed that an increase in the sleeper width by 24% results in the reduction in central settlement and mobilized tensile load by 6.5% and 20.1%, respectively. It was found that with a 50% increase in the thickness of the ballast layer, the central settlement has decreased by 7.3% and the mobilized tension at the zone of maximum curvature has increased by 24.6%. However, with an increase in the thickness of the sub-ballast layer, a considerable reduction in both central settlement and the mobilization of tension on geosynthetic has been noticed. The pattern of variation of settlement and mobilized tension for an increase in the shear modulus of ballast and sub-ballast material was found to be almost similar. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This paper addresses the geotechnical engineering problem of evaluating the ultimate bearing capacity of a strip foundation resting upon a reinforced soil, by means of the yield design homogenization approach. The analysis is notably focused on the determination of the macroscopic strength criterion of such reinforced soils, where both constituents are purely cohesive, which can be conveniently expressed through the notion of anisotropic cohesion. A comprehensive comparison is made between the classical configuration of reinforcing columns and the more original one of orthogonal reinforcing trenches. Among the most outstanding results of the analysis is the conclusion that the cross trench configuration is notably more efficient in terms of load bearing capacity than the reinforcement by columns, notably when significantly inclined loading is concerned. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Building with factory-prefabricated masonry panels made of clay units meanwhile has become a long-established, field-proven construction method. The advantages are shorter construction time for shell constructions, lower construction costs and uniform level of quality as well as high dimensional accuracy of the masonry panels and a production that is independent of weather influences. An innovation in the field of prefabricated masonry is the dry bonding method for prefabricated masonry panels made of clay units whereby, instead of a conventional thin layer mortar, a two-component polyurethane adhesive (2C-PUR) is applied by machine to the flat ground surface of the clay unit. In mid 2013, the Institute of Building Materials Research (ibac) in Aachen was commissioned by Redbloc Deutschland GmbH to carry out tests on masonry prefabricated with 2C-PUR adhesive, to establish the necessary basis for obtaining a general technical approval (abZ) for masonry panels built according to the Redbloc system and thereby lay the foundations for using this new construction method in Germany. This article shall firstly give a survey of the test programme for the approval procedure agreed with the German building authority , Deutsches Institut für Bautechnik (DIBt), and present the key results obtained from the tests carried out in Aachen. Furthermore the individual steps from planning via production in the prefabrication plant right through to transport and assembling of the masonry panels at the building site will be presented, taking the example of the first prefabrication factory of Redbloc Elemente GmbH opened at Plattling in Germany in the meantime. [ABSTRACT FROM AUTHOR]

Die Nutzung oberflächennaher Geothermie ermöglicht eine wirtschaftliche und umweltschonende Bereitstellung regenerativ gewonnener thermischer Energie als Alternative zu einer konventionellen Wärme‐ bzw. Kälteversorgung. Als geothermisches Quellensystem werden zunehmend sogenannte “thermoaktive erdberührte Bauteile” wie z. B. Gründungspfähle oder Bodenplatten verwendet. Deren unter baustatischen Gesichtspunkten erfolgende Herstellung bietet noch deutliches Optimierungspotenzial für die Nutzung als Erdwärmeübertrager. Im Rahmen des europäischen Forschungsprojektes “e‐hub” sind daher rechnergestützte Modellierungsarbeiten zur Untersuchung von Möglichkeiten für die Erhöhung der Leistungsfähigkeit von thermisch aktivierten Gründungspfählen, sogenannten Energiepfählen, durchgeführt worden. Dabei zeigte sich insbesondere bei der Verwendung von gut wärmeleitenden Zuschlagstoffen für den Pfahlbeton eine Steigerung der thermischen Leistungsfähigkeit der Energiepfähle von bis zu ca. 30 %, verglichen mit regulärem Pfahlbeton. Je nach Projektumfang und konstruktiver Pfahlausführung kann durch dessen Verwendung eine deutliche Verbesserung der Energieeffizienz und damit eine nachhaltige Wirtschaftlichkeit des Geothermieprojektes bei moderat erhöhten Herstellungskosten erreicht werden. Potential for optimization of thermally activated foundation piles (energy piles) – A modelling approach from the EU‐funded research project “e‐hub” The use of shallow geothermal energy enables a cost‐effective and environmentally friendly provision of renewable thermal energy as an alternative to conventional heating and cooling supply. As a geothermal source system, so called “thermally activated construction parts” such as foundation piles or floor plates, are being used increasingly often. Those are designed mainly for structural purposes and hence offer significant optimization potential for the use as a geothermal heat exchanger. Therefore computational modeling works have been carried out as part of the European research project “e‐hub”. Their major aim was to investigate options for a performance increase of thermally activated foundation piles, so‐called “energy piles”. A particularly evident performance increase of up to 30 % could be demonstrated for the use of highly thermally conductive aggregates in pile concrete compared with regular concrete. Depending on the actual project scope and the constructive pile design, a significant improvement in energy efficiency and sustainable profitability of real world geothermal projects are expected at moderately increased production costs [ABSTRACT FROM AUTHOR]

Die messtechnische Dauerüberwachung von Bauwerken (Monitoring) wird in immer stärkerem Maße zur Beobachtung und Bewertung bestehender oder neu errichteter Ingenieurbauwerke angewendet. Die gewonnenen Messwerte werden zum Beispiel zur Überprüfung der Rechenannahmen oder für die Beurteilung des Langzeitverhaltens genutzt. Ein anderes Anwendungsfeld stellt dagegen die sicherheitsrelevante Überwachung kritischer Bauzustände mithilfe eines Monitoringsystems dar, welches mit automatisierten Warn‐ und Alarmmeldungen ausgestattet ist. Ein solches System wurde beim Neubau der Tiefgründungen und Dämme der Eisenbahnbrücken über die Aller und die Wätern eingesetzt, um rechtzeitig kritische Veränderungen der unter Eisenbahnverkehr stehenden Brückenbauwerke detektieren zu können. Das Monitoringsystem war als Kompensationsmaßnahme für das bauzeitlich reduzierte Sicherheitsniveau der stark geschädigten Bestandsbrücken vorgesehen. Im Zusammenspiel zwischen dem Anlagenverantwortlichen, der Bauüberwachung und dem Bauwerksgutachter hat sich das Monitoring als leistungsfähiges Werkzeug zur Gewährleistung eines sicheren Eisenbahnbetriebs erwiesen. Monitoring of bridge structures as a tool of construction supervision Structural health monitoring is applied increasingly to supervise and evaluate existing or new structures. The measured values are used for example to verify the computational assumptions, or for assessing the long‐term behavior. In contrast, a different field of application is the safety monitoring of critical construction phases using a monitoring system, which is equipped with automated warning and alarm messages. Such a system was used during the construction of deep foundations and embankments of railway bridges over the river Aller and the creek Wätern. The aim of the system was to timely detect critical changes under railway and construction loads. The monitoring system was planned as a compensatory measure for the reduced level of safety during the replacement of the damaged bridges. Within the interaction between bridge owner, construction supervisor and monitoring expert, the monitoring has proven to be a powerful tool to ensure a safe railway operation even under structural works. [ABSTRACT FROM AUTHOR]

Nachrichten: Deutscher Bautechnik-Tag 2015 in Düsseldorf: Call for Papers. / Die neue Fassung der DIN EN 1997-1:2014-03 (Eurocode 7-1) wird nicht bauaufsichtlich eingeführt! (Dr.-Ing. B. Schuppener) Persönliches: Professor Dr.-Ing. habil. Fritz-Ferdinand Zitscher verstorben. ( Georg Heerten) Firmen und Verbände: Bundesstiftung Baukultur und Förderverein starten gemeinsame Aktion 'Die Bundesstiftung Baukultur stärken. / DWA übernimmt Programm des F. Hirthammer Verlags. Auslobung: Karl-Imhoff-Preis der DWA ausgeschrieben. / Neue Runde im Wettbewerb 'Auf IT gebaut - Bauberufe mit Zukunft'. [ABSTRACT FROM AUTHOR]

Die Gründung von Fundamenten lässt sich prinzipiell zwischen dem Grenzfall der 'flachen' Gründung auf unbehandeltem Untergrund und dem der 'tiefen' auf Pfählen einordnen. Im ersten Fall breitet sich die Spannung aus der gesamten Fundamentlast im Baugrund systematisch aus. Es treten mehr oder weniger große Setzungen auf, die zumindest bei kleinen Fundamenten wegen der Spannungsausbreitung mit der Tiefe verhältnismäßig schnell abklingen. Im zweiten Fall leiten Pfähle fast die gesamte Last in Bodenschichten mit hoher Tragfähigkeit ab. Obwohl es zu keiner nennenswerten entlastenden Spannungsausbreitung kommt, sind die Setzungen dann auch bei hoher Last wegen der großen Pfahlsteifigkeit gering. Zwischen diesen Grenzfällen gibt es viele Gründungsarten oder -kombinationen, die in ihrem Setzungsverhalten weniger leicht einzuschätzen sind. Sie reichen von der sogenannten Pfahl-Plattengründung bis zu bodenverbessernden Maßnahmen. In all diesen Fällen konzentriert sich die Lastabtragung auf den bewehrten oder verbesserten Baugrund unter dem Fundament, aber ein mehr oder weniger großer Teil der Fundamentlast wird auch nach außen auf den unbehandelten Boden abgegeben. Dieser abfließende Teil, nachstehend als Lastausbreitung bezeichnet, lässt sich oft schwer bestimmen. Da er aber eine erhebliche Rolle im Hinblick auf das Setzungsverhalten der Gründung spielen kann, wird hiermit ein brauchbares Berechnungsverfahren vorgestellt, das die jeweilige Lastausbreitung näherungsweise berücksichtigt. The settlement of footings on different kinds of subsoil treatment with reduced load distribution In principal, the foundation of footings can be ranked between the border case of a shallow foundation on unimproved ground and a deep foundation with piles. In the first case the pressure of the total load spreads systematically in the subsoil. More or less large settlements occur but - at least in the case of small footings - they decrease fairly quickly due to the spreading of the pressure with the depth. In the second case piles transfer the load directly to soil strata with high bearing capacity. Although no notably relieving spreading of pressure occurs settlements are small even at a high load due to the stiffness of the piles. In between these two cases there are many foundation methods or combinations with settlement performances that cannot easily be evaluated. They range from the so-called pile-plate foundation to soil improvement below the foundation. In all these cases the load pressure concentrates on the reinforced or improved subsoil under the foundation. However, either more or less of it is delivered to the untreated soil around. This 'escaping' part, hereinafter called 'load distribution' is often difficult to be determined. It may, however, be of substantial importance with regard to the settlement behaviour, so this is to introduce a suitable approximation to consider in a settlement calculation the appropriate load distribution. [ABSTRACT FROM AUTHOR]

Beim Neubau des Blocks 9 des Großkraftwerks Mannheim sind umfangreiche Bauarbeiten zu bewerkstelligen. Aufgrund des begrenzt zur Verfügung stehenden Platzes und zur Kostenoptimierung werden die benötigten Bauteile in ihrer räumlichen Ausdehnung assimiliert. Dies hat zur Folge, dass die Bauwerke immer tiefer in den Untergrund expandieren. Des Weiteren bündeln sich die Bauwerkslasten auf einer immer kleiner werdenden Fläche und müssen vom Untergrund möglichst setzungsunempfindlich aufgenommen werden. Dies bietet ein äußerst facettenreiches Betätigungsfeld für den Spezialtiefbau im Kraftwerksbau. Im Folgenden wird über die Vielfalt der hier zur Anwendung gekommenen Verfahren des Spezialtiefbaus und den damit verbundenen komplexen arbeitstechnischen Aufgaben berichtet. Mannheim power station - foundation engineering in power plant construction. Extensive construction work is to be carried out for the new construction of block 9 at Mannheim power station. Due to the limited space available and to optimize costs, the required components will be assimilated in their spatial dimensions. The consequence of this is that the building works will expand deeper and deeper into the ground. Furthermore, the structural loads will become concentrated on an increasingly smaller space and must be supported from below ground as much as possible to avoid settlement. This offers an exceptionally diverse field of activity for foundation engineering in power plant construction. The following report covers the diversity of the foundation engineering techniques used and the complex procedural tasks associated with them. [ABSTRACT FROM AUTHOR]

Im Zuge des Ausbaus erneuerbarer Energien entstehen in der Nord- und Ostsee Parks aus Offshore-Windenergieanlagen, kurz OWEA. Die Gründung dieser OWEA erfolgt häufig mit großen Einzelpfählen, den sogenannten Monopiles. Infolge der zyklischen Belastung aus Wind und Wellen findet im Baugrund eine Verformungsakkumulation statt, welche zu bleibenden Schiefstellungen der Monopiles führen kann. Für die Prognose dieser nichtlinearen Langzeitverformungen wurden in der Vergangenheit verschiedene Ansätze vorgeschlagen. Mit dem Ziel, die einzelnen Ansätze miteinander zu vergleichen und ihre Grenzen auszuloten, wurden zahlreiche Berechnungen einer OWEA-Monopilegründung mit realitätsnahen Abmessungen und Belastungen in einem nichtbindigen Baugrund mit unterschiedlichen Lagerungsdichten durchgeführt. Dabei wurden folgende Ansätze untersucht: die P-y-Kurven des American Petroleum Institute (API), ein Ansatz nach Dührkop, das ESWM nach Tašan et al., das SDM nach Achmus et al. und ein Ansatz, der am Institut für Bodenmechanik und Felsmechanik (IBF) des Karlsruher Instituts für Technologie (KIT) verwendet und hier mit HIA bezeichnet wird. Die Kalibration der Parameter dieser Ansätze für einen offshore-typischen Feinsand auf der Basis von Laborversuchen wurde in [5] vorgestellt. In diesem Beitrag werden die mit dem jeweiligen Ansatz ermittelten Pfahlverformungen miteinander verglichen. Dabei wird auf die Umsetzung der Ansätze und die betrachteten Belastungen eingegangen, bevor die Ergebnisse der Prognosen vorgestellt werden. Dabei werden große Unterschiede zwischen den Prognosen der einzelnen Ansätze aufgezeigt, obwohl die Parameter der Ansätze am selben Sand und zum Teil aus den gleichen Laborversuchen abgeleitet wurden. Comparison of methods for the prediction of long-term-deformations of OWEA monopile foundations in sand In the process of renewable-energy-development the number of offshore wind parks in the North Sea and the Baltic Sea increases. The offshore wind power plants are often founded on a single large pile, a so-called monopile. The cyclic loading due to wind and waves causes an accumulation of deformation in the soil which may lead to a permanent tilting of the monopiles. Different methods have been developed for the prediction of these non-linear long-term deformations. In this study the predictions made by the various methods are compared for realistic dimensions and loadings of an offshore wind power plant as well as different densities of a non-cohesive soil. The quality and the limitations of the methods were examined. The following methods were studied: the P-y-curves of the American Petroleum Institute (API), a method proposed by Dührkop, the ESWM by Tašan et al., the SDM by Achmus et al. and a method which is used at the IBF (KIT), here referred to as HIA. The calibration of the parameters of the various methods is presented in [5]. In this paper the pile displacements predicted by the different methods are compared with each other. The implementation of these methods and the applied loads are explained before the results are presented. Although the model parameters were determined for the same fine sand and in some cases were obtained using the same experimental results, large differences are observed between the predictions given by each method. [ABSTRACT FROM AUTHOR]

Im Zuge des Ausbaus erneuerbarer Energien entstehen in der Nord- und Ostsee Parks aus Offshore-Windenergieanlagen, kurz OWEA. Die Gründung dieser OWEA erfolgt häufig mit großen Einzelpfählen, den sogenannten Monopiles. Infolge der zyklischen Belastung aus Wind und Wellen findet im Baugrund eine Verformungsakkumulation statt, welche zu bleibenden Schiefstellungen der Monopiles führen kann. Für die Prognose des nichtlinearen Langzeitverformungsverhaltens der OWEA-Monopilegründungen wurden in der Vergangenheit verschiedene Ansätze vorgeschlagen. Mit dem Ziel, die einzelnen Ansätze miteinander zu vergleichen und ihre Grenzen auszuloten, wurden zahlreiche Berechnungen einer OWEA-Monopilegründung mit realitätsnahen Abmessungen und Belastungen in einem nichtbindigen Baugrund mit unterschiedlichen Lagerungsdichten durchgeführt. Dabei wurden folgende Ansätze untersucht: die P-y-Kurven des American Petroleum Institute (API), ein Ansatz nach D ÜHRKOP, das ESWM nach T AŞAN et al., das SDM nach A CHMUS et al. und ein Ansatz, der am Institut für Bodenmechanik und Felsmechanik (IBF) des Karlsruher Instituts für Technologie (KIT) verwendet und hier mit HIA bezeichnet wird. Neben der Beschreibung dieser Ansätze wird in diesem Artikel die Bestimmung der jeweils benötigten Parameter aus Laborversuchen vorgestellt. Die Eingangsparameter aller Ansätze wurden für einen offshore-typischen Feinsand ermittelt. In 'Teil 2: Simulationen und Schlussfolgerungen' werden dann die von den verschiedenen Ansätzen prognostizierten Pfahlverformungen infolge der hochzyklischen Belastung präsentiert und miteinander verglichen. Comparison of methods for the prediction of long-time-deformations of OWEA monopile foundations in sand In the process of renewable-energy-development the number of offshore wind parks in the North Sea and the Baltic Sea increases. The offshore wind power plants are often founded on a single large pile, a so-called monopile. The cyclic loading due to wind and waves causes an accumulation of deformation in the soil which may lead to a permanent tilting of the monopiles. Different methods have been developed for the prediction of these non-linear long-term deformations. In this study the predictions made by the various methods are compared for realistic dimensions and loadings of an offshore wind power plant as well as different densities of a non cohesive soil. The quality and the limitations of the methods were examined. The following methods were studied: the P-y-curves of the American Petroleum Institute (API), a method proposed by D ÜHRKOP, the ESWM by T AŞAN et al., the SDM by A CHMUS et al. and a method which is used at the IBF (KIT), here referred to as HIA. In this article, beside the description of the different approaches, the procedure of parameter calibration will be discussed and the parameters for each method will be retrieved by laboratory tests performed on an offshore-typical fine sand. 'Part 2: Simulations and conclusions' will present and compare the deformations of the monopile foundation due to high-cyclic loading predicted by the different approaches. [ABSTRACT FROM AUTHOR]

According to Eurocode 7, the geotechnical ultimate limit state (ULS) design proof can be provided by either a GEO-2 or a GEO-3 design equation. In offshore engineering applications a GEO-3 proof is usually carried out in the design of laterally loaded piles. In Germany a GEO-2 proof is required according to DIN 1054; this standard also describes a special procedure on how to do this. This paper compares the results of the different approaches. The p-y method, usually used for calculating the pile load-bearing behaviour, is validated with respect to German regulations (e.g. with DIN 4085 regarding ultimate bedding stresses). In general it was found that the p-y method can be used in ULS design. It is further shown that the special ULS design procedure described in DIN 1054 can yield erroneous results (i.e. depending on system parameters and loading type, admissible loads may be either too small or too large). The GEO-3 proof generally produces reasonable results, but here the actual level of safety depends on the soil parameters. This paper recommends a new and simple design procedure, which is a GEO-2 proof but also gives correct admissible pile head loads in all cases considered and allows for the consideration of soils with strength degradation. Zum Tragfähigkeitsnachweis für horizontal belastete Pfähle. Gemäß Eurocode 7 kann der Tragfähigkeitsnachweis (ULS) sowohl im Grenzzustand GEO-2 als auch im Grenzzustand GEO-3 geführt werden. Im Bereich der Offshore Anwendungen ist international der Nachweis für horizontal belastete Pfähle im Grenzzustand GEO-3 üblich. In Deutschland ist dagegen gemäß der DIN 1054 ein Nachweis im Grenzzustand GEO-2 vorgeschrieben, dessen spezielle Vorgehensweise zur Durchführung ebenfalls in dieser Norm dargelegt ist. Im folgenden Artikel werden die Ergebnisse dieser beiden Nachweisverfahren miteinander verglichen. Die p-y Methode, welche üblicherweise zur Ermittlung des Lastverschiebungsverhaltens eingesetzt wird, wird unter Berücksichtigung der deutschen Regularien validiert (d.h. der maximale Bettungswiderstand wird den Ergebnissen der DIN 4085 gegenübergestellt). Hierbei kann die p-y Methode grundsätzlich als geeignet für den Tragfähigkeitsnachweis identifiziert werden. Weiterhin kann gezeigt werden, dass die in der DIN 1054 beschriebene spezielle Vorgehensweise des Nachweises zu fehlerhaften Ergebnissen führen kann (d.h. in Abhängigkeit der Systemparameter und der Belastungsart können die zulässigen Belastungen sowohl zu klein als auch zu groß sein). Der Nachweis GEO-3 gibt grundsätzlich plausible Ergebnisse, allerdings hängt das tatsächliche Sicherheitsniveau von den Bodenparametern ab. Der Artikel empfiehlt einen neuen und einfachen Bemessungsansatz im Grenzzustand GEO-2, der für sämtliche Randbedingungen korrekte zulässige Pfahlkopfbelastungen ergibt. Der Ansatz erlaubt zudem auch die Berücksichtigung von Böden mit Entfestigung. [ABSTRACT FROM AUTHOR]