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Author: Andreas Laudahn Publisher: Logos Verlag Berlin ISBN: 9783832510725 Category : Languages : en Pages : 0
Book Description
Complex problems in geotechnical engineering and soil mechanics can be investigated with physical modelling, where the structures in a geometrically n-times smaller scale are reproduced and the occuring forces and deformations are measured. Problematic is the reduction of pressures and the subsequent change of the mechanical behaviour of the model soil. The versatility of field and model test is shown by examples from the literature. In this thesis the similarity between barotropy and pyknotropy was used to model prototype soil behaviour. Soiltron is a prototype soil, which is treated with light and soft additives to achieve the same relative density in the model at an n-times smaller pressure as in the prototype. The stiffness and strength of the new material can be influenced to simulate prototype material behaviour by the control of the soil density. Thus, the use of that soil as material in small scale 1$g$models is possible. At the Institute of Geotechnical and Tunnel Engineering of the University of Innsbruck a model soil material was not available in sufficient quantity. Therefore, a large quantity of quartz sand was purchased and its mechanical behaviour was investigated in detail with triaxial test devices using local strain gauges. The specimen deformations were inspected with evaluation of remote measurements using PIV. Systematic and random test errors have been avoided or have been taken into account. Appropriate regressions have been found to relate pressure and density to the properties of the soil and to calculate the required density of Soiltron. The appropriateness of Soiltron is verified in two demonstration model tests. This work can be seen as foot step to strike a new path in physical modelling.
Author: Andreas Laudahn Publisher: Logos Verlag Berlin ISBN: 9783832510725 Category : Languages : en Pages : 0
Book Description
Complex problems in geotechnical engineering and soil mechanics can be investigated with physical modelling, where the structures in a geometrically n-times smaller scale are reproduced and the occuring forces and deformations are measured. Problematic is the reduction of pressures and the subsequent change of the mechanical behaviour of the model soil. The versatility of field and model test is shown by examples from the literature. In this thesis the similarity between barotropy and pyknotropy was used to model prototype soil behaviour. Soiltron is a prototype soil, which is treated with light and soft additives to achieve the same relative density in the model at an n-times smaller pressure as in the prototype. The stiffness and strength of the new material can be influenced to simulate prototype material behaviour by the control of the soil density. Thus, the use of that soil as material in small scale 1$g$models is possible. At the Institute of Geotechnical and Tunnel Engineering of the University of Innsbruck a model soil material was not available in sufficient quantity. Therefore, a large quantity of quartz sand was purchased and its mechanical behaviour was investigated in detail with triaxial test devices using local strain gauges. The specimen deformations were inspected with evaluation of remote measurements using PIV. Systematic and random test errors have been avoided or have been taken into account. Appropriate regressions have been found to relate pressure and density to the properties of the soil and to calculate the required density of Soiltron. The appropriateness of Soiltron is verified in two demonstration model tests. This work can be seen as foot step to strike a new path in physical modelling.
Author: Gerd Gudehus Publisher: Springer Science & Business Media ISBN: 3540363548 Category : Science Languages : en Pages : 843
Book Description
Soil is matter in its own right. Its nature can be captured by means of monotonous, cyclic and strange attractors. Thus material properties are defined by the asymptotic response of sand- and clay-like samples to imposed deformations and stresses. This serves to validate and calibrate elastoplastic and hypoplastic relations with comparative plots. Extensions capture thermal and seismic activations, limitations occur due to localizations and skeleton decay.Attractors in the large characterize boundary value problems from model tests via geotechnical operations up to tectonic evolutions. Validations of hypoplastic calculations are shown with many examples, possible further applications are indicated in detail. This approach is energetically justified and limited by critical points where the otherwise legitimate continuity gets lost by localization and decay. You will be fascinated by the fourth element although or just as it is so manifold.
Author: Chien-Hsun Chen Publisher: Logos Verlag Berlin GmbH ISBN: 3832540709 Category : Technology & Engineering Languages : en Pages : 206
Book Description
This work aims at developing a numerical simulation method, Soft PARticle Code (SPARC). The term textit soft emphasizes that no boundaries between particles are defined and every particle possesses a support consisting of a set of adjacent particles. The polynomial interpolation/approximation method is utilized for the evaluation of spatial derivatives using the information carried by particles in supports. The system of equations consisting of spatial derivatives is solved using an iterative nonlinear solver and the computation of the Jacobian matrix is parallelized. The simulations of laboratory tests have been carried out to show the applications and limitations of the current version of SPARC. In addition to the simulations, laboratory (zig-zag) model tests using fine sand were carried out, in which the cyclic tilt of a retaining wall induces a peculiar motion in the backfill (sand), with closed trajectories (eddies).
Author: Gertraud Medicus Publisher: Logos Verlag Berlin GmbH ISBN: 3832540555 Category : Science Languages : en Pages : 136
Book Description
Barodesy is a constitutive model for granular materials. It is based on proportional strain and stress paths and the asymptotic behaviour of soil. In this work, an existing relation for proportional strain paths and proportional stress paths is further developed. A modification of barodesy to model clay behaviour is introduced. Common concepts of soil mechanics, such as critical states, barotropy and pyknotropy are comprised.
Author: Ansgar Kirsch Publisher: Logos Verlag Berlin GmbH ISBN: 3832521496 Category : Technology & Engineering Languages : en Pages : 213
Book Description
Various models have been proposed for the prediction of the necessary support pressure at the face of a shallow tunnel. To assess their quality, the collapse of a tunnel face was modelled with small scale model tests at single gravity. The evolution of the failure mechanism and the development of the support force at the face in dry sand were investigated. The observed displacement patterns show a negligible influence of overburden on the extent and evolution of the failure zone. The latter is significantly influenced, though, by the initial density of the sand: in dense sand a chimney-wedge-type collapse mechanism developed, which propagated towards the soil surface. Initially loose sand did not show any development of a discrete collapse mechanism. The necessary support force was neither influenced by the overburden nor the initial density. A comparison with quantitative predictions by several theoretical models showed that the measured necessary support pressure is overestimated by most of the models. Only those by Vermeer/Ruse and Leca/Dormieux were able to predict the necessary support pressure on a 95 % confidence level. A three-dimensional finite element investigation of face stability served to assess the ability of two constitutive models, an elastoplastic Mohr-Coulomb and a hypoplastic model, to predict the necessary support pressure and the displacements at the tunnel face. The simulation of the small scale experiments revealed that the observed necessary support pressure and incremental displacements were predicted sufficiently well with both constitutive models.
Author: Anastasia Blioumi Publisher: Logos Verlag Berlin GmbH ISBN: 3832535845 Category : Technology & Engineering Languages : en Pages : 218
Book Description
English summary: Rocks composed of parallel layers are cross-anisotropic materials. This thesis describes a new approximate solution for the determination of the properties of these materials based on mold cavity expansion experiments. German description: Gesteine, die aus parallelen Schichten bestehen, sind quer-anisotrope Materialien. Die Disseration beschreibt eine neue Naherungslosung zur Bestimmung der Eigenschaften solcher Materialien, basierend auf Hohlraumaufweitungs- Versuchen. Daten aus Radialpressversuchen dienen der inversen Analyse des Problems. Wenn der innere Druck, der Radius des Hohlraums, die Orientierung der Schieferung und die Verschiebungen bekannt sind, ergibt die Naherungslosung Materialparameter-Kombinationen, die die gemessenen Verschiebungen gut abbilden. Die Losung ist jedoch nicht eindeutig. Dreidimensionale Finite Elemente Modellierung wird in dieser Arbeit verwendet, um Hohlraumaufweitung in linear-elastischem, quer-anisotropem Gestein zu simulieren. Eine numerische Untersuchung wird durchgefuhrt, um das Modell richtig zu etablieren (Randbediengungen, Grosse des Diskretisierungsbereichs usw.) und die moglichen Einflussgrossen (z. B. Genauigkeit der Bestimmung der Schieferungsorientierung) zu beurteilen. Die Ergebnisse der Feldmessungen werden dann mit den numerisch berechneten radialen Verschiebungen der Hohlraumwand verglichen. Letztere entstehen durch die Implementierung von Materialparametern, die aus der genannten Naherungslosung zuruckgerechnet werden. Ahnlichkeiten und Unterschiede werden beschrieben und erklart. Eine alternative Methode zur Ermittlung des Verhaltens von quer-anisotropen Materialien mittels kleinmassstablicher Hohlraumaufweitungs-Laborversuche in einem kunstlichen queranisotropen Material ist ebenfalls erwogen worden. Der Aufbau und die Prinzipien eines solchen Versuchs werden beschrieben und dessen Ausfuhrbarkeit wird untersucht.
Author: Fabian Schranz Publisher: Logos Verlag Berlin GmbH ISBN: 3832548831 Category : Science Languages : en Pages : 220
Book Description
Barodesy is a constitutive model for granular materials such as sand and clay. It is based on the asymptotic behaviour of granular media at a constant deformation rate. In this work the existing sand version of Barodesy is improved. For this purpose, the underlying scalar equations are simplified using different concepts from soil mechanics. The improved version is also compared with laboratory tests and different elastoplastic and hypoplastic constitutive relations. Also the stability of slopes and advanced stress paths such as the rotation of the princple stresses are investigated with these models.
Author: A. Asaoka Publisher: Elsevier ISBN: 9780080428383 Category : Science Languages : en Pages : 956
Book Description
Progressive failure has been a classical problem in the field of geotechnical engineering and has attracted considerable attention in connection with slope stability and foundation problems. It is associated with strain localization or shear banding and is also related to damage in material structures. As knowledge of the progressive failure mechanism increases, it is now necessary to establish effective communications between researchers and engineers. The International Symposium on Deformation and Progressive Failure in Geomechanics provided an opportunity for discussing recent advances in this area. A total of 136 papers were contributed from 22 countries. As well as these, the symposium proceedings also contain 8 interim technical reports on the subject by the members of the Asian Technical Committee of the International Society for Soil Mechanics and Foundation Engineering and the Japanese Geotechnical Society National Committee on Progressive Failure in Geo-structures.
Author: Jacques Desrues Publisher: John Wiley & Sons ISBN: 0470394846 Category : Science Languages : en Pages : 454
Book Description
This book brings together a total of 48 contributions (including 5 keynote papers) which were presented at the 2nd International Workshop on the Application of X-ray CT for Geomaterials (GeoX 2006) held in Aussois, France, on 4-7 October, 2006. The contributions cover a wide range of topics, from fundamental characterization of material behavior to applications in geotechnical and geoenvironmental engineering. Recent advances of X-ray technology, hardware and software are also discussed. As such, this will be valuable reading for anyone interested in the application of X-ray CT to geomaterials from both fundamental and applied perspectives.
Author: Andreas Laudahn
Author: Andreas Laudahn
Author: Gerd Gudehus
Author: Chien-Hsun Chen
Author: Gertraud Medicus
Author: Ansgar Kirsch
Author: Anastasia Blioumi
Author: Fabian Schranz
Author: Die deutsche Nationalbibliothek
Author: A. Asaoka
Author: Jacques Desrues