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Duhrkop J.,IMS Ingenieurgesellschaft mbH | Augustesen A.H.,Cowi A/S | Barbosa P.,Iberdrola
Frontiers in Offshore Geotechnics III - Proceedings of the 3rd International Symposium on Frontiers in Offshore Geotechnics, ISFOG 2015 | Year: 2015

A review of current design methods of axially loaded open ended driven steel piles in chalk is presented. Iberdrola pile testing campaign in Kent, United Kingdom, in low density chalk is described and selected results are presented. These include static axial uplift and compressive tests and a two-way cyclic load test on two 0.76m diameter test piles. A comparison between actual and predicted pile behaviour with RATZ (load-transfer) computer program calibrated with direct simple shear Constant Normal Stiffness (CNS) cyclic laboratory tests is presented. © 2015 Taylor & Francis Group, London.


Barbosa P.,Iberdrola | Geduhn M.,IMS Ingenieurgesellschaft mbH | Jardine R.,Imperial College London | Schroeder F.,Geotechnical Consulting Group LLP | Horn M.,Bilfinger Construction GmbH
Frontiers in Offshore Geotechnics III - Proceedings of the 3rd International Symposium on Frontiers in Offshore Geotechnics, ISFOG 2015 | Year: 2015

Iberdrola is developing the Wikinger offshore windfarm in the German Baltic Sea. The wind turbines will be supported by four legged jackets founded on driven open ended steel piles. Loading will be predominantly axial with shaft resistance governing design. Ground conditions over much of the project area comprise of thick Chalk layers. A review of current pile design methods for Chalk and related onshore pile test campaigns highlighted significant design uncertainties and led to a decision to conduct dynamic and static offshore pile tests at the site. This paper summarizes the aims and rationale of the tests carried out in late 2014, describes the design of the remotely operated testing arrangements and reports on an associated research project that is advancing in conjunction with Imperial College London and Geotechnical Consulting Group. © 2015 Taylor & Francis Group, London.


Grant
Agency: European Commission | Branch: FP7 | Program: CP-IP | Phase: NMP.2013.4.1-2 | Award Amount: 14.74M | Year: 2014

Earth provides natural resources, such as fossil fuels and minerals, that are vital for Europes economy. As the global demand grows, especially for strategic metals, commodity prices rapidly rise and there is an identifiable risk of an increasing supply shortage of some metals, including those identified as critical to Europes high technology sector. Hence a major element in any economys long-term strategy must be to respond to the increasing pressure on natural resources to ensure security of supply for these strategic metals. In todays rapidly changing global economic landscape, mining in the deep sea, specifically at hydrothermal vents and the vast areas covered by polymetallic nodules, has gone from a distant possibility to a likely reality within just a decade. The extremely hostile conditions found on the deep-ocean floor pose specific challenges, both technically and environmentally, which are demanding and entirely different from land-based mining. At present, European offshore industries and marine research institutions have some global advantage through their significant experience and technology and are well positioned to develop engineering and knowledge-based solutions to resource exploitation in these challenging and sensitive environments. However, against an international backdrop of state-sponsored research and development in sea floor resource discovery, assessment and extraction technologies, European operators are at an increasing disadvantage. Hence the recognised need to initiate pilot studies to develop breakthrough methodologies for the exploration, assessment and extraction of deep-sea minerals, as well as investigate the implications for economic and environmental sustainability. The Blue Mining project will address all aspects of the entire value chain in this field, from resource discovery (WP1) to resource assessment (WP2), from exploitation technologies (WP3) to the legal and regulatory framework (WP5).


Vossbeck M.,IMS Ingenieurgesellschaft MbH | Lohning T.,Cowi A/S | Kelm M.,IMS Ingenieurgesellschaft MbH
Stahlbau | Year: 2013

Grouted connections are a central element of offshore monopile foundations. Reliable avoidance of damages during the operation stage is not only important for the prevention of hazards but also of strong economic interest. This article discusses the primary load bearing mechanisms. The numerical analysis of these mechanisms can provide decision guidance for the design and dimensioning of respective structures. This article draws on the experience with the detailed designs of several projects in the realisation phase. Connections without shear keys apply large-scale shell actions for the transfer of the bending moment between the transition piece and monopile. This goes along with comparatively large relative rotation between the two involved tubes. Only a very detailed model detects distinctive stress concentrations. The settlement observed under coexisting vertical force and bending moment can be limited by a conical geometry of the connection. By introducing shear keys, increased loads are observed for the outward positions due to the interaction of global and local effects. © Ernst & Sohn Verlag für Architektur und technische Wissenschaften GmbH & Co. KG, Berlin.


Brunn B.,IMS Ingenieurgesellschaft MbH | Nitschke A.,IMS Ingenieurgesellschaft MbH | Schramm T.,IMS Ingenieurgesellschaft MbH
Bautechnik | Year: 2013

The first challenge of this extraordinary project was the integration of all involved parties: The Indian client, the Norwegian and German construction companies and the authors as general planners and site supervisors being head of a team with two sub-consultants for architecture and building services. The second challenge was Antarctica. Planning bases usually taken from standards had to be ascertained, e.g. wind loads, snow and ice conditions. All materials needed to be suitable for Antarctic climate conditions. A third challenge was the logistics. All components had to fit into 20-foot containers, which in turn required being light enough for helicopter transport. The time frame for construction during the Antarctic summer is short. All boundary conditions are reflected in the building; form and material are suited for the location, climate and logistics. The three-storey container building, which is 52 m long and 30 m wide, can accommodate 47 people and contains laboratories, a garage, workshop, living and office areas, a cinema, fitness room, library, dining hall and lounge with a view of the ocean. The Indian government initiated this state-of-the-art project, which was successfully completed through the co-operation of international participants with passion, faith and respect for each other and nature. © 2013 Ernst & Sohn Verlag für Architektur und technische Wissenschaften GmbH & Co. KG, Berlin.


Grabe J.,University of Management and Technology | Pucker T.,IMS Ingenieurgesellschaft mbH
Frontiers in Offshore Geotechnics III - Proceedings of the 3rd International Symposium on Frontiers in Offshore Geotechnics, ISFOG 2015 | Year: 2015

Pile foundations for multilegged support structures for offshore wind energy plants are commonly installed by pile driving. Vibratory driving for offshore foundation piles is unusual, because of its installation effects. During the installation the soil inside and outside of the pile is compacted and the stresses are reduced. Therefore the bearing capacity of vibratory driven piles is reduced compared to driven piles. A new method is presented to increase the vertical bearing capacity of vibratory driven piles. After the pile installation the soil at the pile toe is braced, such that a soil plug develops. The brace can be caused by geotechnical foams aswell as by mechanical displacement. The potential of this newmethod is drawnup by the use of numerical simulations. A case study is performed to estimate the increase of the bearing capacity depending on the achieved stress increase at the pile toe. Using this new method, the advantages of vibratory driven piles such as its fast and noise reduced installation are combined with increased bearing capacity. The bearing capacity is fully mobilised at very low settlements. Therefore the settlements of this improved pile are expected to be smaller than the settlement of traditional jacked piles under service loads. © 2015 Taylor & Francis Group, London.


Seitz K.-F.,Harburger Schlossstrasse 20 | Pucker T.,IMS Ingenieurgesellschaft MbH | Grabe J.,Harburger Schlossstrasse 20
Geotechnik | Year: 2016

This article presents the application of structural optimization in geotechnical engineering. The general design (topology) of a foundation strip is optimized with respect to its deformation behaviour within the service limit state. The SIMP-method is applied for the topology optimization. Hence, a finite element analysis with Abaqus is combined with an adequate optimization algorithm. A hypoplastic constitutive model for modeling material transitions is used for finite element analysis. Four load cases will be examined. The optimized topology design will be reproduced for the following validation with 1 g physical models. A comparison of the load deformation behavior with non optimized foundations with equal volume is carried out. The presented study shows the applicability and potential of topology optimization in geotechnical engineering. © 2016 Ernst & Sohn Verlag für Architektur und technische Wissenschaften GmbH & Co. KG, Berlin.


Lohning T.,Cowi A/S | Vobbeck M.,IMS Ingenieurgesellschaft mbH | Kelm M.,Cowi A/S
Proceedings of Institution of Civil Engineers: Energy | Year: 2013

In offshore wind turbines grouted connections are generally used to install a transition piece between the steel tower and the monopile foundation. The transition piece is plugged on to the monopile, aligned vertically and the annulus in between is filled with high-strength grout. During service operations unexpected settlement of the transition piece has been observed at several wind turbines. The serious findings have called for additional, extensive numerical analyses for the detailed design of the London Array offshore wind farm. The advanced non-linear finite-element analyses provide a more detailed insight into the structural behaviour of grouted connections. Important effects and a possible mechanism for the settlement at existing wind turbines are detected. The previous practice of designing separately for bending moment and transverse force on the one hand and axial force and torsion on the other hand leads, among other things, to the overestimation of capacity. The interaction has to be taken into account.


Rudolph C.,TU Hamburg - Harburg | Mardfeldt B.,Hamburg Port Authority AoR | Duhrkop J.,IMS Ingenieurgesellschaft MbH
Geotechnik | Year: 2011

In Germany dolphins are commonly designed using a procedure after Blum, 1932, proposed in the EAU 2004. However, internationally the p-y-method is applied more widely for dolphin design. In future, legislature in Germany will change towards allowing the p-y-method besides the Blum-method. For the practioning engineer this raises the question of advantages and disadvantages of both methods. This paper contrasts the underlying principles and presents examples for design calculations to allow for comparison of the two methods. © 2011 Ernst & Sohn Verlag für Architektur und technische Wissenschaften GmbH & Co. KG, Berlin.


Heerten G.,NAUE GmbH and Co. KG | Peters K.,IMS Ingenieurgesellschaft MbH
Geotechnik | Year: 2011

The increasing erection of offshore wind energy generators in the North Sea raises questions about the long-term stability of such structures. Extensive foundation structures in water depths of 10 to 60 m are a significant cost factor compared to land installation. Questions about scour development and measures to protect against scour need to be investigated and solved. In contrast to traditional scour protection provided by tipping mineral components, geotechnical plastics are of increasing interest, because they permit the use of undisturbed ground on the site, are relatively simple and safe to install and also no damage to cable entries or corrosion protection of steel structures needs to be worried about. The article reports on experience so far with scour and scour protection for offshore facilities in the North Sea and the state of the technology in the design, filling and installation of sand containers made of geotextiles around the foundations of offshore wind energy facilities and also refers to investigations already performed. © 2011 Ernst & Sohn Verlag für Architektur und technische Wissenschaften GmbH & Co. KG, Berlin.

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