Wind and wave loads on offshore wind turbines are subjected to change in load direction with time. The influence of that change in load direction is investigated based on unidirectional as well as multidirectional laboratory tests and numerical simulations with monopile foundations in sand. Finite element modeling has been performed using an explicit accumulation model (HCA-Model) which combines the implicit and explicit calculation method to describe the soil behaviour under high cyclic loading. The cyclic simple shear tests were used to enhance and optimize the HCA-Model for change in load direction. Laboratory tests are also performed to determine the parameters of the hypoplastic model with intergranular strain as well as the isoelasticity model for implicit calculation steps. Calculated monopile deformation due to change in load direction give results similar to the cyclic simple shear laboratory tests. Again the importance of the choice of the proper soil model in deformation prognosis is highlighted.

A web-based software is presented which effectively supports the management of geotechnical construction projects and minimizes risks of execution stages. The software is developed and implemented as client-server application in the model-view-controller (MVC) framework of software architecture and it runs without installation procedure in any web browser. Main parts are a graphical user interface for easy administration and user access, a SQL database for storage of all information and a diagram editor to visualize monitoring results. Software development and implementation concerned also user-friendly handling, security aspects, rapid data access and adaptivity during a running project. The paper describes the basic ideas and main features of the developed software in detail and outlines a practical application.

In this paper an internet-based information and monitoring platform for the specific circumstances of geotechnical engineering projects is presented. Many endeavours have been made to support the cooperation in civil engineering by managing information during the last years. It was tried to manage documents as a container of information in so-called document management systems or to represent all information in a single model. The introduced platform is based on a hybrid-model-approach consisting of a model-based information management system holding only key-information and further information in a resource management system (DCMS). The main user interface of the platform is the “Graphical Navigator”. Key-information can be accessed via the Graphical Navigator and one gets a direct access to further information in the DCMS as well. Fast reaction in exceptional situations as well as in daily work gets an extensive support. In practical tests, it could be proved that this platform seems to be an adequate help especially for risk assessment and management in i.e. geotechnical projects. It gets a high acceptance by all participants. Experience and advantages are discussed in this paper. Works on the research project is still taking place for the further proving and completion of the platform.

A method is presented for evaluating the liquefaction strength of partially saturated sand using the compression wave velocity (P-wave velocity), a new indicator of saturation. Based on laboratory test results, an empirical correlation that relates the liquefaction strength with the pore pressure coefficient B is firstly proposed. The strength is defined as the cyclic stress ratio required to cause liquefaction at a specified number of cycles. With the aid of a theoretical relation between B and the P-wave velocity, an explicit correlation of more interest is then established between the liquefaction strength of sand and its P-wave velocity. A comparison of the predictions using this explicit correlation with laboratory measurements shows a satisfactory agreement. The significance of this method lies in that it makes it possible to evaluate the liquefaction strength of sand as affected by saturation through the measurement of P-wave velocity, which can be made not only in the laboratory but particularly in the field.

A new method is proposed to characterize the liquefaction potential of partially saturated sands using P-wave velocity. Based on laboratory test data, an empirical relation that relates the liquefaction resistance with the pore pressure coefficient B is proposed. The liquefaction resistance is defined as the cyclic stress ratio required causing liquefaction at a specified number of cycles. With the aid of a theoretical relation between B and the P-wave velocity, an explicit relationship of more interest is then established between the liquefaction resistance of sand and its P-wave velocity. The significance of this relationship lies in that it allows one to evaluate the liquefaction potential of sand as affected by saturation through the measurement of P-wave velocity, which can be made not only in the laboratory but particularly in the field.

As well known, man-made vibrations may significantly influence the dynamic response of lifelines, bridges, buildings and various other structures. So, vibrations generated by loads moving on a railway track on layered ground, underground explosion-induced stress and/or displacement wave propagation in a surrounding soil-environment and high-speed train induced ground vibrations around tunnels are some examples of such man-made soil vibrations [1]. Dynamic soil-pipeline interaction due to as above soil excitations is also a problem in Structural Civil Engineering related to the wave propagation, moving loads and, from socio-economic points of view, to vibration reduction. In a previous paper [2], the seismic (so, a nature-made soil vibration) soilpipeline interaction had been considered as one of the so-called Inequality Problems of structural engineering [3]. The governing conditions of these problems are equalities as well as inequalities. Indeed, for the case of the general dynamic soil-structure interaction, see e.g. [2], the interaction stresses on the transmitting interface between the structure and the soil are of compressive type only. Moreover, due to in general nonlinear, elastoplastic, tensionless, fracturing etc. soil behaviour, gaps can be created between the soil and the structure. Thus, during strong earthquakes or due to highspeed trains, separation and uplift phenomena are often appeared, as the praxis has shown [2].

Field observations on ground motions from recent earthquakes imply that current knowledge is limited with regard to relating vertical and horizontal motions at liquefiable sites. This paper describes a study with the purpose of clarifying this emerging issue to some extent. A series of numerical analyses is carried out on a liquefiable soil deposit with a verified, fully coupled, nonlinear procedure. It is shown that the transformation of vertical motions in the deposit differs considerably from the transformation of horizontal motions. Both the amplitude and frequency content of the horizontal motions are strongly dependent on the shaking level or the associated nonlinear soil behavior. The transfer function for vertical motions is however likely to be independent of the intensity of input motions; no reduction in the amplitude occurs even in the case of strong shaking. The results are shown to be in consistence with the laboratory observations on shaking table tests and recent field observations that less nonlinearity exists for vertical motions. It is also shown that the possibility exists for using information on spectral ratios between the horizontal and vertical surface motions to quickly identify in situ soil behavior and liquefaction that are not readily covered by conventional field or laboratory experimentation procedures.

The present paper deals with the dynamic soil-structure interaction and especially how the dynamic behaviour of foundations is influenced by their partial or full uplift from the subsoil. The so called condition of partial contact admits only pressure contact stresses. Tensile contact stresses do not occur, so an uplift of the foundation from the soil becomes possible. Obviously this problem of soil-structure interaction is a nonlinear one. In this paper a numerical approach will be presented for treating problems in conjunction with partial contact in the time domain by using the substructure method. Here the approach is elaborated for rigid foundations but can also be extended to elastic foundations without difficulties. The results given here show clearly the influence of partial uplift and demonstrate the importance of this effect on soil-structure interaction problems.

A systematic study of medium plasticity marine clays obtained at two locations in Greece is presented on the basis of resonant column tests on undisturbed samples. Results for shear modulus and damping ratio are given over wide ranges of the shearing strain amplitude. Available empirical relationships for the low strain shear modulus are reviewed. The effects of void ratio, plasticity index and effective confining pressure are quantified. The shear modulus vs, strain curves as well as the damping ratio vs. strain curves are approximated by means of simple formulae for use in practice.

New traffic lines and large private and federal building complexes are under construction in the city of Berlin. This paper gives informations about geological, geotechnical and environmental aspects of the ongoing engineering works.

Earthquake Engineering & Structural DynamicsVolume 13, Issue 1 p. 129-131 Short Communication Discussion on a paper by L. A. Ortiz, R. F. Scott and J. Lee S. Savidis, S. Savidis Technical University Berlin, Germany Professor.Search for more papers by this authorH. Klapperich, H. Klapperich Technical University Berlin, Germany Research Assistant.Search for more papers by this authorW. Sarfeld, W. Sarfeld Technical University Berlin, Germany Professor.Search for more papers by this author S. Savidis, S. Savidis Technical University Berlin, Germany Professor.Search for more papers by this authorH. Klapperich, H. Klapperich Technical University Berlin, Germany Research Assistant.Search for more papers by this authorW. Sarfeld, W. Sarfeld Technical University Berlin, Germany Professor.Search for more papers by this author First published: January/February 1985 https://doi.org/10.1002/eqe.4290130112Citations: 1 AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Citing Literature Volume13, Issue1January/February 1985Pages 129-131 RelatedInformation

Wastes of uraniurn mining in the former East Germany were disposed in old openpit mines and valeys, which are bordered with rockfill dams. The soil material in these tailings h ave grain sizes from clay to middle sand. Resulting from partially high water contents the soil material have thixotropical conditions. Lang-term protection of these tailings required a dam-stability design due to seismic loading. The ground is formed by metamorphie clay shales or middle-strong sand- and claystones. An analysis of regional seismicity showed value for the seismic site intensity from 7 to 8 degrees at MSK-scale. The computation of the dynamic stresses and strains in the dams were performed in the time-domain by finite-element analyses by the method of Seed. Dynamic soil properties were determined by resonant column and cyclic triaxial tests in connection with in situ borehole tests. For the dam stability analysis the classic theory of failure circle surfaces was used whereby the material softening due to dynamic loading was taken into account.

Wastes of uranium mining in the former East Germany were disposed in old openpit mines and valleys,which are bordered with rockfill dams. The soil material in these tailings have grain sizes from clay to middle sand. Resulting from partially high water contents the soil material have thixotropical conditions. Long-term protection of these tailings required a dam-stability design due to seismic loading. The ground is formed by metamorphic clay shales or middle-strong sand- and claystones. An analysis of regional seismicity showed value for the seismic site intensity from 7 to 8 degrees at MSK-scale. The computation of the dynamic stresses and strains in the dams were performed in the time-domain by finite-element analyses by the method of Seed. Dynamic soil properties were determined by resonant column and cyclic triaxial tests in connection with in situ borehole tests. For the dam stability analysis the classic theory of failure circle surfaces was used whereby the material softening due to dynamic loading was taken into account.