Seismic Behaviour of Water Front Structures with Tyre Chip Backfill

Water front structures have suffered significant damage in many of the recent earthquakes. One of the primary causes for the poor performance of these classes of structures is the liquefaction of the foundation soil and in some instances liquefaction of the backfill soil. The liquefaction of the soil in-front of the quay wall tends to cause large lateral displacements and rotation of the wall. Full or partial liquefaction of the backfill can result in the increase of lateral earth pressure exerted on the wall that can cause additional lateral displacement of the wall. In this paper numerical analyses of a gravity wall type water front structure will be considered. Often such gravity walls are placed on rubble mound that is deposited onto the sea bed. The problem will be based on a generic model although the simplifications in the generic model were derived based on observed failures of quay walls following the 1995 Kobe earthquake. The paper presents finite element analyses of such a problem in which strength degradation of the foundation soil and the backfill material will be modelled using PZ mark III constitutive relationship. At the Port and Airport Research Institute (PARI) in Japan the possibility of using tyre chips from used car tyres as the backfill material is being researched using 1G underwater shaking table and dynamic centrifuge modelling. The finite element analyses will be repeated by including a zone of backfill consisting of the tyre chips. The properties of this material will be derived from the element tests carried out at PARI. Finally the results from the analyses of the gravity wall founded rubble mound with liquefiable foundation soil and backfill will be compared to those with tyre chip backfill. The improvement in the performance of the wall in terms of decreased lateral displacements and/or reduction in the rotation suffered by the wall will be compared

leap ucd 2017 centrifuge tests at cambridge

As part of the LEAP project the seismic response of a liquefiable 5° slope was modelled at a number of centrifuges around the world. In this paper the two experiments conducted at Cambridge University are discussed. The model preparation is detailed with particular emphasis on the sand pouring, saturation and slope cutting process. The presence of the third harmonic in the input motion is shown and its significance discussed. The potential for wavelet denoising to filter random electrical noise from the pore pressure traces is illustrated. CPT strength profiles are highlighted and a possible softer layer in one of the tests is discussed. Whilst the specifications called for one dense and one loose test, the likelihood that both Cambridge tests were loosely poured is assessed. The PIV technique is used to obtain the displacements of the slope during the test. Finally, the correspondence between the PIV displacements and physical measurements of the marker movements is compared

Coping strategies and mood profiles in patients with multiple sclerosis

Objective: The aim of the present study was to investigate the coping strategies, mood characteristics and the association between these aspects in patients diagnosed with multiple sclerosis and healthy subjects. Method: Fifty consecutive patients who were diagnosed with multiple sclerosis according to McDonald criteria and thirty-one healthy subjects were included in the study. In addition to the sociodemographic form, Expanded Disability Status Scale (EDSS), Coping Orientation for Problem Experiences Scale (COPE), and Profile of Mood States (POMS) tests were applied to the participants. Results: Non-functional coping strategies were significantly higher in the secondary-progressive type (p≤0.05). Depression-dejection, fatigue-inertia and total POMS scores were significantly higher in the secondary-progressive type (p≤0.05). Conclusion: The results of our study demonstrate the importance of rehabilitation programs that encourage exercise among patients with multiple sclerosis to increase vigor-activity levels

Particle Image Velocimetry analysis in dynamic centrifuge tests

The Particle Image Velocimetry (PIV) technique is an image processing tool to obtain instantaneous velocity measurements during an experiment. The basic principle of PIV analysis is to divide the image into small patches and calculate the locations of the individual patches in consecutive images with the help of cross correlation functions. This paper focuses on the application of the PIV analysis in dynamic centrifuge tests on small scale tunnels in loose, dry sand. Digital images were captured during the application of the earthquake loading on tunnel models using a fast digital camera capable of taking digital images at 1000 frames per second at 1 Megapixel resolution. This paper discusses the effectiveness of the existing methods used to conduct PIV analyses on dynamic centrifuge tests. Results indicate that PIV analysis in dynamic testing requires special measures in order to obtain reasonable deformation data. Nevertheless, it was possible to obtain interesting mechanisms regarding the behaviour of the tunnels from PIV analyses. © 2010 Taylor & Francis Group, London

Lateral and Axial Capacity of Monopiles for Offshore Wind Turbines

Offshore wind has enormous worldwide potential to generate increasing amounts of clean, renewable energy. Monopile foundations are considered to be viable in supporting larger offshore wind turbines in shallow to medium depth waters. In this paper, the lateral and axial response of monopiles installed in undrained clays of varying shear strength and stiffness is investigated using three-dimensional finite element analysis. A combination of axial and lateral loads expected at an offshore wind farm located in a water depth of 30 m has been used in the analysis. Numerically derived monopile axial capacities will be compared to those calculated using an established method in the literature. In addition, the lateral monopile capacity will be determined at ultimate limit state and compared to that at the serviceability limit state. Through a parametric study, it will be shown that with the exception of extremely high axial loads that border on monopile axial capacities, variation in axial loads does not have a significant effect on the ultimate lateral capacity and lateral displacement of monopiles. © 2013 Indian Geotechnical Society