• Magazine of the Korea Concrete Institute
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• v.7 no.1
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• pp.58-67
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• 1995

• Journal of the Korean Geotechnical Society
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• v.21 no.4
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• pp.5-12
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• 2005

Recently, geophysical prospecting methods have played very important roles in civil and environmental engineering problems. Technical advances in geophysical instruments and computer system made it possible to get underground images with very high resolution far purposes to resolve those problems. It was possible partly due to ever increasing demand for development of technologies needed to precisely detect polluted areas and prevent ground-related accidents. Based on the same demand, integrity tests of cast-in place piles draw more attention and development of accurate test procedures is required. Ultrasonic methods is one of most advanced non-destructive procedures. In the paper, a geotomography method is employed for the cast-in place pile integrity test using ultrasonic waves. The image of pile interior is scanned and scrutinized far better and more accurate decision in the cast-in place pile integrity. In this study, we firstly examined the accuracy fur tomography program with idealized synthetic models built in water tank: their position and size were changed in the tank and each case was studied. In the next stage, real concrete pile models were fabricated and images of anomaly areas inside the pile were scanned to successfully locate those areas.

• Journal of the Korea institute for structural maintenance and inspection
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• v.27 no.2
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• pp.8-16
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• 2023

This study evaluated a shear capacity of confined socket-bolt (CSB) shear connector developed for utilizing cast in placed pile (CIP) as a permanent underground wall. The push-out tests were performed in the specimens with different CIP types, CSB shear connector types, L/d, and concrete compressive strengths of concrete pile, and with or without waterproofing at interfaces between CIP and underground wall. Test results showed that the specimens with a H-shaped pile were fractured in the CSB shear connector, while the fracture concentrated in the concrete part of the specimens with a reinforced concrete pile was alleviated as the compressive strength of the concrete pile increased, resulting in the severe fracture of CSB shear connector. The maximum shear capacities of the specimens with high strength bolts and reinforcing bars used as CSB shear connector were approximately 1.22 and 1.20 times higher than those of the specimens with a H-shaped pile, respectively, and 1.10 and 1.16 times higher than those of the specimens with a reinforced concrete pile, respectively. Meanwhile, the maximum shear capacity was not significantly affected by the embedding length of the CSB shear connector and overlapping length of reinforcing bar. The predicted shear capacities calculated from the KDS standards were lower than the measured values of all specimens tested in this study.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.1132-1143
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• 2008

A single Column/Shaft which extended the pile to the column of the bridge with same diameter has better safety and economical profit, but it usually has larger lateral displacement due to lateral loads such as wind, earthquake, wave, etc. A series of horizontal pile load testing were performed to study the lateral behavior of single column/shaft with varying different free lengths and embedded pile lengths. Eight instrumented test piles were cast-in-placed by bonding strain gauges at certain locations on both faces of the pile to measure bending moment, from two-way loadings. Linear variable differential transformers(LVDTs) were installed to measure the lateral pile displacement. Based on this, it is found that the test single column/shaft with different free lengths shows different failure modes. If the test pile has a longer free length, the failure occurs at the near the ground surface, but the shorter one's failure occurs at the below the ground surface.

• Journal of the Korean Geotechnical Society
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• v.22 no.4
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• pp.11-19
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• 2006

For the last decade, the hi-directional testing method has been advantageous over the conventional pile load testing method in many aspects. However, because the hi-directional test uses a loading mechanism entirely different from that of the conventional pile load testing method, many investigators and practicing engineers have been concerned that the hi-directional test would give inaccurate results, especially about the pile head settlement behavior. Therefore, a hi-directional load test and the conventional top-down load test were executed on 1.5 m diameter cast-in-situ concrete piles at the same time and site. Strain gauges were placed on the piles. The two tests gave similar load transfer curves at various depth of piles. However, the top-down equivalent curve constructed from the hi-directional load test results predicted the pile head settlement under the pile design load to be about one half of that predicted by the conventional top-down load test. To improve the prediction accuracy of the top-down equivalent curve, a simple method that accounts for the pile compression is proposed. It was also shown that the strain gauge measurement data from the hi-directional load test could reproduce almost the same top-down curve.