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Geotechnical Centrifuge Testing Center
Analytical Service Last update : 2017.09.05 Request for use
Photos
Location
W16 291 Daehak-ro Yuseong-gu, Daejeon 34141, Republic of Korea
Homepage
www.koced.or.kr/en/
Coordinating Country
KOREA
Hosting Organisations
Korea Advancece Institute of Science and Technology (KAIST)
Contact Person
DongSoo Kim,+82-42-350-3619,dskim@kaist.ac.kr
RI Category
Civil Engineering Research Infrastructures
Keywords
Geotechnical structures,Dynamics,Physical modeling,Disaster,Earthquake simulation
Description
- Ensure the model testing facilities by performance evaluation of a large geotechnical structures, design verification, development of new technologies
- Building construction engineering test facilities which are lacking in domestic distributed throughout the country and Korean researchers can enjoy the jointly research foundation that can be used to share data by connecting the high-speed communication network
- Promote the domestic construction technology by activating the model demonstration
Application Area
- Dams, embankments, foundations, slope and large scale model testing of geotechnical structures
- Evaluation of the earthquake disaster simulation testing various infrastructure using a centrifuge shaking table test
- Related college majors through the scale model testing and training of graduate students
- Geotechnical structures design validation, epidemiological studies on disasters
Service
Specifications
1. Geotechnical Centrifuge
- Platform radius: 5.0 m, Max. capacity: 240 g-tons, Max. acceleration: 130 g with 1,300 kg payload
2. Shaking table
- Shaking type: Electro-hydraulic servo type,Max. model payload: 700 kg,Max. shaking acceleration: 20 g for full payload,Experimental frequency range: 40 to 300 Hz
3. Four Degree-of-Freedom In-Flight Robot
- Stroke: 0.8 m(X), 0.6 m (Y), 0.5 m(Z), 175°(),Max. speed: 50 mm/s(X, Y, Z), 5°/s()
4. Data Acquisition System
- Total of 192 channels for accelerometers, strain gages, LVDTs, Earth pressure, Pore pressure, etc.

Publication

Lee, H., Kim, D. S., Choo, Y. W. Journal of Geotechnical and Geoenvironmental Engineering, 140(10), 04014059. doi: 10.1061/(ASCE)GT.1943-5606.0001167.

The authors present a method for calculating a mooring line’s tension and angle of inclination at the anchor pad eye to analyze the behavior of a mooring line embedded in sand. They adopted the governing equation from a previous study for clay and reanalyzed the frictional and bearing resistances. The authors performed a number of centrifuge tests at two anchor depths while maintaining relative densities of 76 or 51% in the cylindrical test box to validate the proposed analytical method. The analytical solutions agreed well with the test results and the results of the simplified method. The authors conducted a parametric study to evaluate the effects of various factors on the behavior of an embedded mooring line in sand, including the depth of the attachment point, the internal friction angle of sand, the submerged unit weight of sand, the angle of the mooring line on the seabed, and the self-weight and nominal diameter of the mooring line. The results demonstrated that the proposed analytical method is effective for analyzing the behavior of a mooring line embedded in sand.

Chung Nguyen, D. D., Kim, D. S., Jo, S. B. Journal of Geotechnical and Geoenvironmental Engineering, 139(10), 1690-1698. doi: 10.1061/(ASCE)GT.1943-5606.0000908.

In the design of piled raft foundations, the control of total and differential settlements is crucial. On the basis of centrifuge tests, this study presents the feasibility of a fairly optimal pile arrangement scheme for reducing total and differential settlements. Two models of piled raft foundations having the same flexible raft and number of piles, the uniform pile arrangement model and the concentrated pile arrangement model, and one model having a rigid raft with a concentrated pile arrangement were designed for centrifuge tests. The settlements of three rafts of the piled raft models and the induced bending moments of two flexible rafts were measured during the load application process. The measured results were compared between the tests to illustrate the ability of the concentrated pile arrangement scheme in reducing total and differential settlements, as well as induced bending moment. Moreover, three piled rafts were simulated by the Plaxis 3D Foundation software package to calculate the total and differential settlement, as well as the induced bending moments, after which a comparison was made with the centrifuge tests to verify the reliability of these tests. The results show that the piled raft model with a concentrated pile arrangement can effectively decrease the total and differential settlements in comparison with the pile raft model with a uniform pile arrangement.

Kim, J. H., Choo, Y. W., Kim, D. J., Kim, D. S. Geoenvironmental Engineering, 142(3), 04015090. doi:10.1061/(ASCE)GT.1943-5606.0001425

Miniature cone penetration tests were conducted in centrifuge models to investigate the effects of various testing conditions on the tip resistance including the particle size, centrifugal acceleration related to stress level and prototype cone diameter, container wall boundary, and penetration rate. Two sand materials were selected: (1) Saemangeum and (2) silica sands. The former is natural sand with high fine contents and the latter is clean sand. A series of penetration tests was performed in six saturated soil models using an in-flight robot. Three Saemangeum sand models were prepared by means of the moist compaction method. The silica sand models were made by the air-pluviation method. Modeling of models was adopted to investigate the particle size effect using 7-, 10-, and 13-mm-diameter cones. The centrifugal acceleration effect also was studied by comparing the tip resistance profiles obtained at different g-levels using the 10-mm-diameter miniature cone. The results indicated that the particle size effect was negligible for both sands using 7- to 13-mm-diameter cones. However, the tip resistance decreased with increasing g-level at a shallower depth than a given critical depth (Dcr), especially for dense sand. Then, it merged to a single value at a deeper depth than Dcr. The Dcr was affected by g-level and soil density. Finally, an empirical correlation to estimate the soil density from the tip resistance in the centrifuge was proposed.

Seong, J. T., Ha, J. G., Kim, J. H., Park, H. J., Kim, D. S. Wind Energy. 2017. doi:10.1002/we.2127.

Understanding of dynamic response of offshore wind turbine is important to reduce vibration of offshore wind turbine induced by structural and environmental loadings. Although dynamic characteristics of the offshore wind turbine such as natural frequency and seismic behavior are affected by foundation and soil conditions, there are little experimental studies about the dynamic behavior of offshore wind turbine with consideration of proper soil–foundation–structure interaction (SFSI). The goal of this research is to evaluate the natural frequency and seismic behavior of offshore wind turbine with a monopod foundation considering SFSI. Scaled model of offshore wind turbine and monopod foundation is produced for this research. Geotechnical centrifuge tests in fixed-based and SFSI condition were performed to measure natural frequency in each case. Also, a series of seismic loadings with different intensities are applied to observe seismic behaviors of the offshore wind turbine during the earthquake and permanent changes after the earthquake. Experimental results show apparent natural frequency reduction in SFSI condition compared with the fixed-based condition, non-linear changes in dynamic response during a series of earthquakes and permanent changes occurred in natural frequency and rotational displacement after earthquakes.

Kim, D. J., Choo, Y. W., Kim, J. H., Kim, S., Kim, D. S. Journal of Geotechnical and Geoenvironmental Engineering, 140(5), 04014008. doi: 10.1061/(ASCE)GT.1943-5606.0001083

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 6.5min diameter and 8.0min 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 momentrotation 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.

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