1,721,118 research outputs found
General report for TC104 physical modelling in geotechnics
No full textThe session of the 18th ICSMGE on physical modelling in geotechnics, held by Technical Committee 104, provides an opportunity to reflect on the varied contributions that physical modelling makes to our profession - in both research and practice. The 27 papers contributed within this theme span many different applications of physical modelling. These range from simple small-scale laboratory tests to reveal mechanisms of soil-structure interaction - particularly where simulation by numerical methods is problematic -Through to scaled-down versions of field constructions, performed outdoors, to validate the performance of new monitoring technology. These examples show physical modelling in action across the entire spectrum of geotechnics, from the validation of fundamental analysis principles, to the assurance of construction technology. In all cases, physical models - defined here as physical idealisations of all or part of an envisioned geotechnical system - provide a more convenient method of gaining knowledge than observing or simulating the full geotechnical system.</p
Capacity of dynamically embedded plate anchors as assessed through field tests
No full textA dynamically embedded plate anchor (DEPLA) is a rocket-shaped anchor that penetrates to a target depth in the seabed by the kinetic energy obtained through free-fall and by the anchor’s self-weight. After embedment, the central shaft is retrieved leaving the anchor flukes vertically embedded in the seabed. The flukes constitute the load bearing element as a plate anchor. This paper presents and considers field data on the embedment depth loss due to the plate anchor keying process and the subsequent bearing capacity factor of the plate anchor element. The loss in plate anchor embedment was significantly higher than that reported from corresponding centrifuge tests and is reflected in the larger padeye displacements required to mobilize peak capacity in the field tests. Measured plate capacities and plate rotations during keying indicate that the end of keying coincides with the peak anchor capacity. Experimental bearing capacity factors are in the range Nc = 14.3–14.6, which is appreciably higher than existing solutions for vanishingly thin circular plates. The higher Nc for the DEPLA is considered to be due to a combination of the cruciform fluke arrangement and the fluke (or plate) thickness
Centrifuge modeling to support the design of subsea pipelines
No full textOffshore geotechnical engineering is characterized by unusual soil and loading conditions, a continuously moving frontier resulting in the requirement for innovative geotechnical solutions, and the very high cost associated with in-situ soil characterization and field testing in remote and deep oceans. As a consequence, offshore engineering practice has probably benefitted more from centrifuge modeling than other domains of geotechnical engineering, since the first offshore projects performed in 1973. After a brief overview of the role and contribution centrifuge modeling has had on offshore geotechnics, the paper illustrates the influence centrifuge modeling in recent years in improving the understanding of subsea pipe-soil interaction, to assist the development of guidelines and recommendations for practitioners, and in being used to design subsea pipelines in offshore Australia.</p
Towards a simple design procedure for dynamically embedded plate anchors
No full textDynamically embedded plate anchors (DEPLAs) are a promising option for anchoring floating facilities in deep water, as relative to current technology such as suction caissons, the anchor will be much smaller and less expensive to install. This paper considers data from the final stage of an experimental campaign that has been undertaken as a preliminary step towards qualification of the DEPLA at full scale. The experiments involved field testing of a 1:4·5 reduced-scale DEPLA in approximately 50?m water depth at a site off the west coast of Scotland. Measurements in the tests included accelerations during free fall in water and embedment in soil, and pullout resistance as the DEPLA was loaded to failure and subsequently retrieved to the deck of the installation vessel. The acceleration data are used in the paper to explore the suitability of strain rate formulations for scaling the undrained shear strength to values appropriate for dynamic penetration, and to demonstrate the potential for a dynamic penetration model to predict the final anchor embedment depth. The paper finishes by summarising output from the embedment model in a simple design chart that can be used to scale a DEPLA for a given mooring line load
New centrifuge modelling techniques for investigating seabed pipeline behaviour
No full textThe paper outlines newly-developed centrifuge modelling techniques for simulating the dynamic laying of seabed pipelines and the near-surface properties of seabed soils, which were created in response to the increasing need to characterise this behaviour in design. Several examples in artificial and natural soils are presented, highlighting notably the remoulding behaviour and its effect on pipe embedment.</p
Pierre Poumier (1885-1974)
No full textAllaire Jean-Marie, Gaudin C., Lebrun Claude, Léonard Jacques. Pierre Poumier (1885-1974). In: Annales de Bretagne et des pays de l'Ouest. Tome 82, numéro 3, 1975. pp. 241-250
Development of a multiple-axis actuator control system
No full textThe paper details the characteristics of a multiple axis actuator control system, the Package Actuator Control System or PACS, developed at the University of Western Australia. The system was developed to answer the increasing need for highly complex motion and load sequences to be applied during centrifuge model tests. It features four PID controllers, each driving an independent axis of actuator motion (or controlling another tool), a waveform generator and sequence controller. These modules are contained within a single intuitive user interface. This interface allows seamless switching between automated and manual control, resulting in simultaneous independent automated control of the four axes in load and/or displacement control. All of the researchers and technicians involved in experiments using the UWA beam centrifuge are capable of operating this system, after brief training by the beam centrifuge operator, supported by the software author.</p
Setup following keying of plate anchors assessed through centrifuge tests in kaolin clay
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Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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