			Home About us Contact

Ground Conditions (ground + condition)

Distribution by Scientific Domains

Engineering	60%

Selected Abstracts

Consistency of dynamic site response at Port Island

EARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 6 2001
Laurie G. Baise
Abstract System identification (SI) methods are used to determine empirical Green's functions (EGF) for soil intervals at the Port Island Site in Kobe, Japan and in shake table model tests performed by the Port and Harbor Research Institute (PHRI) to emulate the site during the 17 January 1995 Hyogo-ken Nanbu earthquake. The model form for the EGFs is a parametric auto-regressive moving average (ARMA) model mapping the ground motions recorded at the base of a soil interval to the top of that interval, hence capturing the effect of the soil on the through-passing wave. The consistency of site response at Port Island before, during, and after the mainshock is examined by application of small motion foreshock EGFs to incoming ground motions over these time intervals. The prediction errors (or misfits) for the foreshocks, the mainshock, and the aftershocks, are assessed to determine the extent of altered soil response as a result of liquefaction of the ground during the mainshock. In addition, the consistency of soil response between field and model test is verified by application of EGFs calculated from the shake table test to the 17 January input data. The prediction error is then used to assess the consistency of behaviour between the two cases. By using EGFs developed for small-amplitude foreshock ground motions, ground motions were predicted for all intervals of the vertical array except those that liquefied with small error. Analysis of the post-liquefied ground conditions implies that the site response gradually returns to a pre-earthquake state. Site behaviour is found to be consistent between foreshocks and the mainshock for the native ground (below 16 m in the field) with a normalized mean square error (NMSE) of 0.080 and a peak ground acceleration (PGA) of 0.5g. When the soil actually liquefies (change of state), recursive models are needed to track the variable soil behaviour for the remainder of the shaking. The recursive models are shown to demonstrate consistency between the shake table tests and the field with a NMSE of 0.102 for the 16 m to surface interval that liquefied. The aftershock ground response was not modelled well with the foreshock EGF immediately after the mainshock (NMSE ranging from 0.37 to 0.92). One month after the mainshock, the prediction error from the foreshock modeled was back to the foreshock error level. Copyright © 2001 John Wiley Sons, Ltd. [source]

Feature: Implications of climate change for hazardous ground conditions in the UK

GEOLOGY TODAY, Issue 2 2004
Alan Forster
Many geohazards affect the United Kingdom, both directly and indirectly. As climate might change in the future, it may affect the geohazards that we, and our descendents, will have to face as a consequence of those changes. [source]

Requirements for ground investigations in shield tunnelling / . Anforderungen an die Baugrunderkundung für Schildvortriebe

GEOMECHANICS AND TUNNELLING, Issue 3 2010
Dietmar Placzek Prof. Dr.-Ing.Article first published online: 1 JUN 2010
Mechanized tunnelling; Reconnaissance; Maschineller Vortrieb; Baugrunderkundung Abstract The success of a tunnel project depends on successfully overcoming the ground conditions and the geological risks. Despite this basic fact, the production of technical regulations and guidelines, the further development of machine technology and improving methods of surveying and control, mishaps still often occur during tunnel drives, affecting either the tunnel itself or the surroundings, e.g. existing infrastructure or buildings. The causes are often multifaceted but can almost always be attributed to the existing ground conditions, which had not been appropriately determined, described, or considered in the design, or taken into account during construction. The following explanations describe the risks inherent in ground conditions and show how these risks can be countered by appropriate ground investigations for tunnelling. Der Erfolg eines Tunnelvortriebs hängt von der sicheren Beherrschung des Baugrunds und der hierin liegenden Risiken ab. Trotz dieser grundlegenden Erkenntnis, der Erarbeitung von technischen Vorschriften und Richtlinien, der Weiterentwicklung der Maschinentechnik sowie einer verfeinerten Mess- und Steuerungstechnik kommt es immer Tunnelvortrieb wieder beim zu Schäden, die entweder unmittelbar den Vortrieb selbst oder das Umfeld, z. B. bestehende Infrastruktur oder Bauwerke, betreffen. Die Ursachen sind häufig vielfältiger Natur, lassen sich aber überwiegend auf die vorherrschenden Baugrundverhältnisse zurückführen, die entweder nicht zutreffend ermittelt, beschrieben, planerisch umgesetzt oder ausführungstechnisch berücksichtigt wurden. Die nachfolgenden Ausführungen beschreiben die im Baugrund vorhandenen Risiken und zeigen auf, wie diesen Risiken durch gezielte Baugrunduntersuchungen für den Tunnelbau begegnet werden kann. [source]

From hypothetical scenario to tragic reality: A salutary lesson in risk communication and the Victorian 2009 bushfires

AUSTRALIAN AND NEW ZEALAND JOURNAL OF PUBLIC HEALTH, Issue 1 2010
Robin Burns
Abstract Objective: To investigate the ways that the risk of a bushfire emergency and communication strategies are perceived by different community segments. Methods: A brief questionnaire preceded focus group discussion of a bushfire scenario with four communications from different sources. Groups were recruited to represent different community segments within a bushfire-prone peri-urban Shire in Victoria. Results: Four groups (28 participants) were recruited. Bushfire experience was highest in the over 40-year-olds, who would use a variety of information sources, preferred to receive information from trusted local sources, such as emergency services and the council, and were more likely to be a member of a local organisation than the under 40s. Younger people used television, local papers, and friends, family and neighbours as information sources. Young parents felt disempowered through lack of local knowledge, and trusted government departments less than older residents. All wanted clear, current, specific local information about ground conditions and actions to be taken during a fire outbreak. Conclusions/implications: Knowledge of and preparedness for bushfire is unequally spread throughout a bushfire community. There is a need in public health risk and emergency situations to focus on community development, information and consultation. [source]