A Newly Developed State-of-the-Art Geotechnical Centrifuge in Korea
01 Jan 2013-Ksce Journal of Civil Engineering (Korean Society of Civil Engineers)-Vol. 17, Iss: 1, pp 77-84
TL;DR: The first large scale geotechnical centrifuge in Korea has recently been developed at KAIST under the Korea Construction Engineering Development (KOCED) Collaboratory program as discussed by the authors.
Abstract: The first large scale geotechnical centrifuge in Korea has recently been developed at KAIST under the Korea Construction Engineering Development (KOCED) Collaboratory program. A 5 m platform radius, 240 g-tons state-of-the-art geotechnical centrifuge has been installed in a new facility. The centrifuge has the unique feature of an automatic balancing system and includes parts for general testing purposes such as fluid rotary joints, slip rings, a fiber optic rotary joint and an Ethernet network system. In addition, a four degree-of-freedom in-flight robot can be equipped to simulate complex construction or in-situ testing process during centrifuge flight. In order to simulate earthquake motion during operation, a self-balancing type biaxial shaking table has also been developed. Since the KOCED program promotes collaboration and remote use, tele-presence and tele-participation environments have been implemented in this facility.
Citations
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TL;DR: In this paper, a large number of dynamic centrifuge tests and corresponding seismic response analyses were performed to evaluate the dynamic performance of a newly constructed ESB model container and to shed light on the range of testable soil conditions.
75 citations
TL;DR: In this paper, a series of dynamic centrifuge tests was designed and conducted to study the seismic behavior of buried box tunnels and numerical simulations of the same tests were also performed using a finite difference software.
66 citations
TL;DR: In this article, the authors performed load tests of a tripod bucket foundation preliminarily designed as a supporting system of wind turbines and compared the results to those obtained from a test of a monopod bucket foundation.
Abstract: This paper performed centrifuge load tests of a tripod bucket foundation preliminarily designed as a supporting system of wind turbines and compared the results to those obtained from a test of a monopod bucket foundation. The tripod foundation prototype studied in this study has three bucket caissons, each of which is 6.5 m in diameter and 8.0 m in length. The center-to-center distance between the buckets was 26.9 m. The site is composed of an 11-m thick layer of dense silty sand overlying a thick sandy silt layer. The horizontal load was applied at a height of 33 m from the seabed floor according to the design load condition, and the vertical load was simulated by the self-weight of the model. The moment-rotation angle curves for the tripod foundations were compared with that of the monopod bucket foundation. The moment-rotation curve of the tripod was nearly bilinear, whereas that of the monopod showed a gradual decrease in slope. The yield moment for the tripod foundation was half that of the monopod, but the rotation angle for the yield moment was only 20% that of the monopod. The behavior of the tripod foundation under a cyclic load with respect to the accumulated plastic deformation has also been examined in this study. When the resultant moment of cyclic loading was smaller than the monotonic yield moment, negligible accumulated plastic deformation was observed for both one-way and two-way loading. However, when the resultant moment was higher than the monotonic yield moment, significant cumulated deformation resulted.
60 citations
TL;DR: In this article, the authors present the development of experimental p-y relationships for large-diameter monopiles in dense sands based on results from centrifuge tests exhibiting a softer monopile behavior than those proposed by the API and Reese methods.
Abstract: The validity of using the existing numerical p-y methods [American Petroleum Institute (API) and Reese methods] for the design of offshore wind turbines’ large-diameter monopiles in sands is questionable, as many researchers have raised concerns related to the diameter effects in p-y models. This study presents the development of experimental p-y relationships for large-diameter monopiles in dense sands based on results from centrifuge tests exhibiting a softer monopile behavior than those proposed by the API and Reese methods. The effect of socketing the tip of a pile in rock bearing layers was also investigated. The initial gradients of the p-y relationships in dense sand layers were shown to become significantly stiffer as the depth reaches the much stiffer and stronger rock-bearing layer. The lateral load-displacement curves obtained based on the developed experimental p-y relationships were found to be well matched with the measured lateral load-displacement curves; therefore, it was conclude...
60 citations
TL;DR: In this paper, the authors proposed a framework for considering an economical design methodology in which piles are placed more densely beneath the column positions when the piled raft is subjected to column loads. But this increase does not satisfy the requirement for economical design.
51 citations
References
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TL;DR: In this paper, the authors show that the stress/strain behavior of soil alters with change of effective pressure p and specific volume v. The range of values of a new equivalent liquidity LI5 = LI+0·5 log (p′/5) associated with yielding is 1·9
Abstract: The Cambridge Geotechnical Centrifuge routinely tests models made of up to 0·2 m3 of soil, at accelerations up to 125g. Self-weight effects in models and in corresponding prototypes are similar within a few per cent. Seepage and diffusion of pore water into the plane section of an unlined tunnel serve to illustrate scaling relationships. The stress/strain behaviour of soil alters with change of effective pressure p′and specific volume v. A theory of plasticity explains cohsolidation and yielding in shear at states above critical, but failures below critical state involve rupture or fracture. The range of values of a new equivalent liquidity LI5 = LI+0·5 log (p′/5)associated with yielding is 1·9
789 citations
"A Newly Developed State-of-the-Art ..." refers background in this paper
...In the field of geotechnical engineering, reduced-scale physical modeling is often conducted within a large centrifuge in order to provide correct scaling of the self-weight stresses (Schofield, 1980; Taylor, 1995; Gaudin et al., 2009)....
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01 Jan 1995
TL;DR: A N Schofield Geotechnical centrifuges: past, present and future - Dr W H Craig Centrifuge modelling: practical considerations - R N Taylor Retaining walls and soil-structure interaction - W Powrie Buried structures and underground excavations as mentioned in this paper.
Abstract: Foreword - A N Schofield Geotechnical centrifuges: past, present and future - Dr W H Craig Centrifuge modelling: practical considerations - R N Taylor Retaining walls and soil-structure interaction - W Powrie Buried structures and underground excavations - R N Taylor Foundations - O Kusakabe Dynamics - R S Steedman and X Zeng Environmental geomechanics and transport processes- P J Culligan-Hensley and C Savvidou Cold regions' engineering - C C Smith Conclusions. Appendix. References.
373 citations
"A Newly Developed State-of-the-Art ..." refers background in this paper
...In the field of geotechnical engineering, reduced-scale physical modeling is often conducted within a large centrifuge in order to provide correct scaling of the self-weight stresses (Schofield, 1980; Taylor, 1995; Gaudin et al., 2009)....
[...]
Journal Article•
86 citations
TL;DR: In this article, a series of staged centrifuge tests was performed by applying real earthquake records from 0.05 to 0.5g and the distributions of amplification ratio differed depending on the magnitude of earthquake loading and the zoning condition.
54 citations
TL;DR: In this paper, the authors describe a novel high-speed wireless data acquisition system (WDAS) developed at the University of Western Australia for operation onboard a geotechnical centrifuge, in an enhanced gravitational field of up to 300 times Earth's gravity.
Abstract: This paper describes a novel high-speed wireless data acquisition system (WDAS) developed at the University of Western Australia for operation onboard a geotechnical centrifuge, in an enhanced gravitational field of up to 300 times Earth's gravity. The WDAS system consists of up to eight separate miniature units distributed around the circumference of a 0.8 m diameter drum centrifuge, communicating with the control room via wireless Ethernet. Each unit is capable of powering and monitoring eight instrument channels at a sampling rate of up to 1 MHz at 16-bit resolution. The data are stored within the logging unit in solid-state memory, but may also be streamed in real-time at low frequency (up to 10 Hz) to the centrifuge control room, via wireless transmission. The high-speed logging runs continuously within a circular memory (buffer), allowing for storage of a pre-trigger segment of data prior to an event. To suit typical geotechnical modelling applications, the system can record low-speed data continuously, until a burst of high-speed acquisition is triggered when an experimental event occurs, after which the system reverts back to low-speed acquisition to monitor the aftermath of the event. Unlike PC-based data acquisition solutions, this system performs the full sequence of amplification, conditioning, digitization and storage on a single circuit board via an independent micro-controller allocated to each pair of instrumented channels. This arrangement is efficient, compact and physically robust to suit the centrifuge environment. This paper details the design specification of the WDAS along with the software interface developed to control the units. Results from a centrifuge test of a submarine landslide are used to illustrate the performance of the new WDAS.
37 citations
"A Newly Developed State-of-the-Art ..." refers background in this paper
...In the field of geotechnical engineering, reduced-scale physical modeling is often conducted within a large centrifuge in order to provide correct scaling of the self-weight stresses (Schofield, 1980; Taylor, 1995; Gaudin et al., 2009)....
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