• Proceedings of the Korean Geotechical Society Conference
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• 1995.10a
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• pp.1.1-10
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• 1995

• Proceedings of the Korean Institute of Industrial Safety Conference
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• 2004.04a
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• pp.212-217
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• 2004

• Proceedings of the Korean Geotechical Society Conference
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• 1995.03a
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• pp.43-54
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• 1995

• Proceedings of the Korean Geotechical Society Conference
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• 1995.03a
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• pp.55-68
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• 1995

• Proceedings of the Korean Geotechical Society Conference
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• 1995.03a
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• pp.69-92
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• 1995

• Geotechnical Engineering
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• v.28 no.3
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• pp.23-29
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• 2012

• Journal of the Korean Geotechnical Society
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• v.31 no.11
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• pp.5-13
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• 2015

For the bearing capacity evaluation, dynamic pile tests instead of static pile tests have been commonly used in embedded piles, which are known to have low noise and low vibration construction method. The objective of this study is to analyze the bearing capacity and penetration behaviors of embedded piles, which are constructed in different ground conditions, by using force and velocity signals obtained in the final blows during construction of embedded piles. For the dynamic pile analyses, the CAse Pile Wave Analysis Program (CAPWAP) and Wave Equation Analysis of Piles (WEAP) have been commonly used. In this study, the CAPWAP and WEAP are used for the analyses of the dynamic pile tests, which are conducted on embedded piles. The input values, output values, and force-velocity graphs of CAPWAP determined by analyzing the measured force-velocity signals are investigated. In addition, similar force-velocity singals are obtained from the WEAP by analyzing the input values of the WEAP. Considering the subsurface investigation results around the pile tips, if the N-value increases exponentially along the depth, toe quake value should be small, and therefore large bearing capacity is identified. On the contrary, if the N-value increases linearly, the bearing capacity is small because of large toe quake value. Furthermore, the stiffness of hammer cushion and pile cushion, which is difficult to find correct values, is recommended lower than 500 kN/mm. This study demonstrates that the results of WEAP may be similar to those of CAPWAP and the WEAP can be used to estimate the bearing capacity of embedded piles.

• Journal of the Korean GEO-environmental Society
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• v.5 no.3
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• pp.31-39
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• 2004

The bored pile is widely used as a low noise and vibration piling method in Korea. However, there is design tendency to minimize the friction capacity of the bored pile because of uncertainty and the quality control specification is not set up. This research analysed the strength characteristics of cement paste after the uniaxial compression test with various condition. Test results show that the compressive strength of cement paste with w/c=0.83 was up to $156.0kgf/cm^2$, and the lower w/c ratio and the longer age, the strength of cement paste increased. Also the higher soil mixing ratio, the strength of soil cement decreased, and too high soil mixing ratio caused the malfuction of soil cement. Also this research analysed the 188 dynamic pile test results which were performed before and after hardening of cement paste. Analysis result showed that the average ultimate unit friction capacity was $9.1tf/m^2$ and this result surpassed the common design criteria of the bored pile.

• Journal of the Korean Geotechnical Society
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• v.33 no.1
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• pp.5-15
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• 2017

Skin friction may be one of the most critical factors in designing the prebored and precast pile. Special attention was given to the interface behavior of cement milk-surrounding soil during the installation of prebored and precast pile. Small-scale field model pile test was conducted for the case of single pile. The size and geometry of the small-scale field model piles were designed with pile length 1.3m, boring diameter 0.067 m. Quick maintain-load test was conducted for the cases of boring diameter 150, 125, 90, 86, 74 mm and water-cement ratio 90, 70, 60%. It was shown that the bearing capacity of the pile increased as the cement-water ratio and cement milk thickness increased. Considering the scale effect between the small-scale model test and the actual construction site, it was found that cement milk thickness of 0.1~0.4D (50~200 mm) was reasonable for the stability of the structure. Also, the proper cement paste water / cement ratio was about 70% when considering the results of this study and quality control.

• Geotechnical Engineering
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• v.9 no.4
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• pp.7-16
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• 1993

Calibration chamber tests were conducted on open -ended model piles driven into dried siliceous sands with different soil conditions in order to clarify the effect of soil conditions on plug capacity, The model pile used in the test series was devised so that the bearing capacity of an open -ended pile could be measured out into three components , outside shaft resistance. plug resistance and tip resistance. Under several assumption, the value of earth pressure coefficient in the soil plug is calculated. It is gradually reduced with increase in the longitudinal distance from the pile tip. At the bottom of soil plug, it tends to decrease with increase in the penetration depth and relative density, and to increase with the increase of ambient pressure. In comparison of measured and calculated plug capacities using the one -dimensional analysis, we note that API code and one -dimensional analysis combined with P suggested by Randolph et al. and O'Neill et al. result in great underestimation of the plug capacity. Therefore, based on the test results, an empirical equation was suggested to compute the earth pressured coefficient to be used in the calculation of plug capacity using the one -dimensional analysis. and it produces proper plug capacities for all soil conditions.