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Retaining Structure (retaining + structure)
Selected AbstractsThe influence of the construction process on the deformation behaviour of diaphragm walls in soft clayey groundINTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 7 2006R. Schäfer Abstract Conventional numerical predictions of deep excavations normally neglect the construction process of the retaining structure and choose the earth pressure at rest as initial condition at the beginning of the simulation. The presented results of simulation and measurements during the construction process of the Taipei National Enterprise Center show, that such an assumption leads to an underestimation of the horizontal wall deflection, the surface ground settlements as well as the loading of the struts in case of normally to slightly over-consolidated clayey soil deposits. The stepwise installation process of the individual diaphragm wall panels results in a substantial modification of the lateral effective stresses in the adjacent ground. Especially the pouring process of the panel and the fresh concrete pressure causes a partial mobilization of the passive earth pressure and a distinct stress level increase in the upper half of the wall. As a consequence of the increased stresses prior to the pit excavation, up to 15% greater ground and wall movements are predicted. Moreover, the increased stress level due to the installation process of the diaphragm wall leads to substantial higher strut loadings during the excavation of the pit. Copyright © 2006 John Wiley & Sons, Ltd. [source] Modelling of earth and water pressure development during diaphragm wall construction in soft clayINTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 13 2004R. Schäfer Abstract The influence of a diaphragm wall construction on the stress field in a soft clayey soil is investigated by the use of a three-dimensional FE-model of seven adjacent wall panels. The installation procedure comprises the excavation and the subsequent pouring of each panel taking into account the increasing stiffness of the placed fresh concrete. The soft clay deposit is described by a visco-hypoplastic constitutive model considering the rheological properties and the small-strain stiffness of the soil. The construction process considerably affects the effective earth and pore water pressures adjacent to the wall. Due to concreting, a high excess pore water pressure arises, which dissipates during the following construction steps. The earth pressure finally shows an oscillating, distinct three-dimensional distribution along the retaining wall which depends on the installation sequence of the panels and the difference between the fresh concrete pressure and the total horizontal earth pressure at rest. In comparison to FE-calculations adopting the earth pressure at rest as initial condition, greater wall deflections and surface ground settlements during the subsequent pit excavation can be expected, as the average stress level especially in the upper half of the wall is increased by the construction procedure of the retaining structure. Copyright © 2004 John Wiley & Sons, Ltd. [source] The transfer matrix method applied to steel sheet pile wallsINTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 6 2003D. A. Kort Abstract This paper proposes two subgrade reaction models for the analysis of steel sheet pile walls based on the transfer matrix method. In the first model a plastic hinge is generated when the maximum moment in the retaining structure is exceeded. The second model deals with a beam with an asymmetrical cross-section that can bend in two directions. In the first part of this paper the transfer matrix method is explained on the basis of a simple example. Further the development of two computer models is described: Plaswall and Skewwall. The second part of this paper deals with an application of both models. In the application of Plaswall the effect of four current earth pressure theories to the subgrade reaction method is compared to a finite element calculation. It is shown that the earth pressure theory is of major importance on the calculation result of a sheet pile wall both with and without a plastic hinge. In the application of Skewwall the effectiveness of structural measures to reduce oblique bending is investigated. The results are compared to a 3D finite element calculation. It is shown that with simple structural measures the loss of structural resistance due to oblique bending can be reduced. Copyright © 2003 John Wiley & Sons, Ltd. [source] 2D modelling of a dry joint masonry wall retaining a pulverulent backfillINTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 12 2010A. S. Colas Abstract This work focuses on an analysis of dry joint retaining structures based on yield design theory: the stability of the masonry is assessed using rigid block and shear failure mechanisms in the wall and its backfill. An application of this simulation on 2D scale-down brick and wood models is then addressed, showing close agreement between theoretical predictions and experimental results. Further development on this work, including application of this theory on dry-stone retaining walls, is discussed as a conclusion. Copyright © 2009 John Wiley & Sons, Ltd. [source] Erfahrungen mit dem Spannungs-Verformungsverhalten von mit Geogittern bewehrten StützkonstruktionenBAUTECHNIK, Issue 11 2007Florian Bussert Dr.-Ing. Seit mehreren Jahrzehnten hat sich der Bau geokunststoffbewehrter Erdkörper erfolgreich bewährt. Die Errichtung der Stützkonstruktionen auf stark wechselndem oder gering tragfähigem Untergrund, bei hohen Verkehrslasten oder großen Konstruktionshöhen hat sich vielfach als äußerst ökonomische und ökologische Alternative zu klassischen Bauweisen bewiesen. Um Erfahrungen mit einer neuen Bauweise zu sammeln, wird häufig die sogenannte Beobachtungsmethode angewandt, d.h., das Spannungs-Verformungs-Verhalten wird sowohl während der Erstellung als auch in der ersten Nutzungsphase des Bauwerks messtechnisch ermittelt. Aus diesen Messergebnissen wird deutlich, dass auch bei hoher Beanspruchung der Konstruktionen die Gesamtverformungen kleiner sind als erwartet. Vor allem die gemessenen Dehnungen der Geogitter sind kleiner als die berechneten Werte. Das derzeit verwendete Konzept zur Abschätzung der Dehnungen scheint damit weit entfernt vom tatsächlichen Verhalten derartiger Konstruktionen. Die Erfahrungen von ausgeführten Baumaßnahmen werden vorgestellt und die Ergebnisse diskutiert. Experiences with the tension deformation behaviour of retaining structures reinforced with geosynthetics. Since several decades the application of geosynthetic-reinforced earth bodies successfully worked. The establishment of the retaining structures on strongly changing or small load-carrying underground, with high live loads or large construction heights proved itself often as extremely economic and ecological alternative to classical building methods. In order to gain experiences with a new building method, frequently the so-called observation method is used, which means the stress-deformation behaviour becomes both while the construction and the first utilization phase of the building is determined by measuring techniques. From these results of measurement it becomes clear that also when high loaded the total deformations of the constructions are smaller than expected. From all the measured results the deformations of the geosynthetics are smaller than the analyzed values. The concept for the estimation of the deformations, used at present, seems far thereby from the actual behaviour of such constructions. The experiences of completed structures are presented and the results are discussed. [source] Überprüfung und Bewertung der seismischen Bemessungsgrößen nach DIN 19700 am Beispiel der Thüringer TalsperrenBAUTECHNIK, Issue 12 2004Jochen Schwarz Dr.-Ing. Durch die DIN 19700 werden Talsperren u. ä. Wasserbauwerke hinsichtlich ihrer Bedeutung, ihres Stauvolumens und Höhe (bzw. Stauhöhe) in unterschiedliche Klassen eingeteilt, verbunden mit unterschiedlichen Anforderungen an die Auslegung und Nachweisführung. Da die Talsperren in seismisch unterschiedlich aktiven Erdbebengebieten liegen, sind die Nachweisanforderungen in Abhängigkeit von der Gefährdung (Erdbebenzonen mit bestimmten Intensitätsintervallen) zu staffeln. Es wird untersucht, welche Anforderungen aus der Einführung DIN 19700 abzuleiten sind und wie auf Ebene der Bundesländer die praktische Umsetzung erfolgen kann. In diesem Zusammenhang wird die Thüringer Technische Anleitung Stauanlagen gesondert gewürdigt, die gegenüber der DIN veränderte Festlegungen beinhaltet. Im folgenden werden Grundzüge einer vereinheitlichten Vorgehensweise für den Freistaat Thüringen entwickelt und die notwendigen Bearbeitungsphasen erläutert. Sie sind so gestaltet, daß Synergieeffekte erreicht werden können und eine Übertragbarkeit auf die anderen Bundesländer gewährleistet ist. Examination and evaluation of seismic design criteria according to DIN 4149 by the example of the Thuringia dams. According to the new DIN 19700 dams and other water retaining structures are classified with respect to their storage capacity and height leading to differentiated demands on design and safety verification. Since the dams are located in quite different seismic regions, these demands have to reflect the level of seismic hazard (in terms of zones expressing different intensity intervals). The paper investigates the requirements connected with the introduction of DIN 19700 and the problems arising when implementing the code in a nation-wide scale acknowledging the federal system in Germany. In this context and due to some normative elements, deviating from DIN 19700, the Thuringian Technical Guide is considered more in detail. Basic contours of a unified strategy for the state of Thuringia and the required steps of action are presented. The procedure allows for effects of synergy by maintaining the transformability of the guidelines to other German States. [source] | ||||||||||