• Journal of the Korean Geotechnical Society
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• v.23 no.4
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• pp.161-167
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• 2007

In this study, ultimate lateral load capacity of piles is analyzed with consideration of lateral stress effect. Based on results obtained in this study, a method for the estimation of ultimate lateral load capacity is proposed. This makes it possible to more realistically estimate the ultimate lateral load capacity under various stress states caused by in-situ soil condition and pile installation process. Calibration chamber test results with various soil conditions were used in the analysis. From the test results, it was found that effect of the lateral stress was greater than that of the vertical stress on the ultimate lateral load capacity of piles. It was also found that, as the relative density increases, displacements required to reach the ultimate state increases, showing relative displacements of around 14% and 18-25% for $D_R$ : 55% and 86%, respectively. Based on results obtained in this study, a methodology for the estimation of ultimate lateral load capacity of piles using correction factors was proposed. Results from proposed method matched well measured results.

• Journal of the Korean Geotechnical Society
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• v.23 no.3
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• pp.123-131
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• 2007

A series of CIDC triaxial tests and cone penetration tests in calibration chamber were performed to investigate the relationship between state parameter and normalized cone resistance far dredged Busan sand. From the results of the triaxial tests, the critical state line of Busan sand was established, and the critical state parameters found to be $M=1.39(\phi_{cs}=34^{\circ}),\;\Gamma=1.07$ and $\lambda=0.068$. By analyzing the state parameters and corresponding cone resistances for calibration chamber specimens, the relationship between normalized cone resistance and state parameter for Busan sand was defined as $(q_c-p)/p'=27.6\exp(-10.9\Psi)$. This relationship was also shown to be independent of the stress history. From the comparison of the slope of the normalized cone resistance, m, and the normalized cone resistance at $\Psi=0$, $\kappa$, with those of various sandy soils from over the world, the relationship of m and $\kappa$ with $\lambda_{ss}$ of Busan sand was concluded to show a good agreement with the result published previously, while Busan sand had the largest $\kappa$ among the soils with similar $\lambda_{ss}$ values.

• Journal of Navigation and Port Research
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• v.26 no.1
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• pp.106-111
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• 2002

The estimation of pile bearing capacity is important since the design details are determined from the result. There are numerous ways of determining the pile design load, but only few of them are chosen in the actual design. According to the recent investigation in Korea, the formulas proposed by Meyerhof based on the SPT N values are most frequently chosen in the design stage. In the study, various static and dynamic formulas have been used in predicting the allowable bearing capacity of a pile. Further, the reliability of these formulas has been verified by comparing the perdicted values with the static and dynamic load test measurements. Also, in most cases, these methods of pile bearing capacity determination do not take the time effect consideration, the actual allowable load as determined from pile load test indicates severe deviation from the design value. The principle results of this study are summarized as follows : As a result of estimate the reliability in criterion of the Davisson method, t was showed that Terzaghi & Peck >Chin>Meyerhof > Modified Meyerhof method was the most reliable method for the prediction of bearing capacity. Comparisons of the various pile-driving formulas showed that Modified Engineering News was the most reliable method. However, a significant error happened between dynamic bearing capacity equation was judged that uncertainty of hammer efficiency, characteristics of variable, time effect etc... was not considered. As a result of considering time effect increased skin friction capacity higher than end bearing capacity. It was found out that it would be possible to increase the skin friction capacity 1.99 times higher than a driving. As a result of considering 7 day's time effect, it was obtained that Engineering news, Modified Engineering News, Hiley, Danish, Gates, CAPWAP(CAse Pile Wave Analysis Program) analysis for relation, repectively, $Q_{u(Restrike)} / Q_{u(EOID)} = 0.98t_{0.1}$ , $0.98t_{0.1}$, $1.17t_{0.1}$, $0.88t_{0.1}$, $0.89t_{0.1}$, $0.97t_{0.1}$.

• The Journal of the Petrological Society of Korea
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• v.1 no.1
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• pp.49-57
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• 1992

Whole rock and mineral ages for the Jecheon Granite distributed in the Ogcheon Fold Belt were dated by three radiometric methods, and its thermal history was elucidated as follows, on the basis of isotopic age data. Rb and Sr isotopic compositions of three whole rock and seven mineral concentrates made an isochron of 202.7${\pm}$ 1.9 Ma with a strontium initial ratio of 0.7140. Different age data of twelve mineral concentrates agree closely with the retention temperature of each mineral in K-Ar and Fission Track methods. The Jecheon granitic magma was generated by partial melting of crustal materials (S-type), or by mixins between mantle and crustal materials, intruded into the katazone or mesozone (7∼9 km) of the Ogcheon Fold Belt, at least in the Early Jurassic (about 203 Ma), and then crystallized and cooled down rapidly from about 600$^{\circ}C$ to 300$^{\circ}C$ (more than 20$^{\circ}C$/Ma), owing to thermal differences between the magma and the wall-rock. During the Middle to Late Jurassic (190∼140 Ma), the cooling of the granite was likely to stop and keep thermal equilibrium with the wall-rock. The severe tectonism associated with igneous activities and active weathering on the surface in Early to Late Cretaceous time (140∼70 Ma) might have accelerated the granite pluton to uplift rapidly (40∼60 m/Ma in average) up to 3∼4 km and cooled down from 300$^{\circ}C$ to 200$^{\circ}C$ (1.4 $^{\circ}C$/Ma). The granite pluton was likely to keep different uplifting and cooling rate of about 120 m/Ma and 5$^{\circ}C$/Ma in average from the Late Cretaceous to Early Tertiary (70∼50 Ma), and about 60 m/Ma and 2$^{\circ}C$/Ma in average from about 50 Ma up to the present, respectively.

• Journal of the Korean Society of Groundwater Environment
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• v.1 no.2
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• pp.100-104
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• 1994

The rock matrix diffusion provides a retarding mechanism for sorbing and especially non-sorbing radionuclides. It has to be verified not only theoretically and experimentally but also from natural phenomena, before the mechanism can be incorporated fully into transport codes. The natural analogue studies, such as the concentration variation of radionuclides in profiles perpendicular to fluid-conducting fractures and to intrusive contact zones, have been believed to provide a validation. In thermal alteration zones of Naeduckri granite intruded by a pegmatite, large alkali and alkaline earth elements such as K, Rb, Sr, and Ba were moderately migrated during thermal alteration. Li, V. and Nb were also migrated about 9cm in width from the contact between the granite and the pegmatite. The concentration variation of these elements in thermally altered zones seems to be resulted from the local migration due to the re-equilibration among the elements released from the breakdown of primary minerals in the granite. Most of these natural analogue studies simply show only the concentration variation of elements without detailed informations on the diffusion time and other important data fir interpreting the behaviour of radionuclides, because of the absence of appropriate minerals for age data. Despite this problem, natural analogue studies will be needed for transport models of radionuclides in safety assessment.

• Journal of the Korean Geotechnical Society
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• v.28 no.10
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• pp.41-54
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• 2012

This paper is to develop the method of surface soil improvement by electric heating equipment. For this purpose, the electric heating systems were invented to apply to the in-situ soil. Iaboratory tests were done to study the behaviors of sea clays by eletric heating. In lab tests, two different heating temperatures, $70^{\circ}C$ and $110^{\circ}C$, were applied to the saturated clays to examine the relationship between evaporation and compaction. In addition, trafficability was analyzed to the heated by applying cone penetrometer to the heated clays Furthermore, in-situ tests were conducted to analyze the range of soil improvement and strength variations. The temperature changes in field were measured and they were compared with those of the commercial program (Temp/W). Also, the bearing capacities of electrically heated field were tested by PBT (plate bearing test). Several conclusions were derived from the results of the numerical analysis and tests (lab and field). The improvement ranges and strength variations of electrically heated soil depended on the heating temperature and time. If the heating temperature is more than $100^{\circ}C$ evaporating the ground water, the bearing capacity and settlement increased rapidly. The bearing capacities of in-situ soil increased more than 3 times, and heated soil emitted a lot of vapors. The soil around electric heater was sintered completely, and its range was almost 20 cm.

• Journal of the Korean GEO-environmental Society
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• v.17 no.9
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• pp.37-45
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• 2016

This study analyzes the environmental and durability problems of traditional (LW) grouting method. And the proposed method was compared to the others effects by analyzing the in-situ applicability and effect of performance of the method using the silica sol. This study analyzed the eco-friendly, effects of high strength silica sol through laboratory tests. The effects of the construction process were identified through the field tests. The compressive strength was increased by 1.3 times compared to the LW method and the shrinkage is 3~8 times less than that of LW method with water glass. No toxicity, which could affect soil contamination. In particular, it was confirmed that the Toxicity fish also survived with little pH change in the concentration tank. Also it confirmed the construction effects through field test. Field tests are a standard penetration test, permeability test, LLT, BST. Permeability was reduced to $1{\times}10^{-5{\sim}-6}cm/sec$.

• Journal of the Korean Geotechnical Society
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• v.38 no.5
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• pp.5-17
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• 2022

A pile is a type of medium for constructing superstructures in weak geotechnical conditions. A pretensioned spun high-strength concrete (PHC) pile is composed of high-strength concrete with a specified strength greater than 80 MPa. Therefore, it has advantages in resistance to axial and bending moments and quality control and management since it is manufactured in a factory. However, the skin friction of a pile, which accounts for a large portion of the pile bearing capacity, is only approximated using empirical equations or standard penetration test (SPT) N-values. Particularly, there are some poor research results on the pile-soil interface under the seismic loads in Korea. Additionally, some studies do not consider geoenvironmental elements, such as groundwater pH values. This study performs sets of cyclic simple shear tests using submerged concrete specimens for 1 month to consider pH values of groundwater and clay specimens composed of kaolinite to generate a pile-soil interface. 0.2 and 0.4 MPa of normal stress conditions are considered in the case of pH values. The disturbed state concept is employed to express the dynamic behavior of the interface, and the disturbed function parameters are newly suggested. Consequently, the largest disturbance increase under basic conditions is observed, and an early approach to the failure under low normal stress conditions is presented. The disturbance function parameters are also suggested to express this disposition quantitatively.

• Journal of the Korean Geotechnical Society
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• v.24 no.8
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• pp.137-148
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• 2008

In this study, 28 earthquake records with magnitudes from 5.3 to 7.9 are selected for dynamic analysis in order to assess applicability of the earthquakes for domestic seismic design. The assessment is performed using the seismic spectrum analysis of energy and acceleration. Based on results of the analysis, four acceleration time histories, which satisfy the Korean design standard response spectrum, are proposed. From the dynamic analysis using earthquake magnitudes from 6.4 to 7.9, it is found that horizontal displacements corresponding to earthquake magnitudes greater than 7 are two times larger than those with magnitude 6.5. Therefore, it can be stated that use of strong earthquakes, such as Miyagiken-ken-oki earthquake (Ofunato, $M_{JMA}=7.4$) and Tokachi-oki earthquake (Hachinohe, $M_{JMA}=7.9$), for the seismic design in Korea is not applicable, and may prove to be excessively conservative due to overestimated seismic force. From the dynamic analyses using the proposed acceleration time histories, effects of caisson quay wall dimension and the subsoil condition are investigated as well. The simplified design charts to evaluate horizontal displacements of caisson quay wall are also proposed based on earthquake magnitude 6.5 that is appropriate in Korea.

• The korean journal of orthodontics
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• v.37 no.1 s.120
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• pp.44-55
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• 2007

Objective: Previous studies have reported that morphological features of the first cervical vertebra (atlas) have been associated with mandibular growth direction. The purpose of this study was to show the possible positional and morphological changes of the Atlas from activator treatment in Class II malocclusion patients. Methods: Lateral cephalometric radiograph tracings were made at initial, middle and final stages of treatment. Angular and linear measurements of skeletal and morphological features were measured on the anatomical landmarks and reference planes. Results: The skeletal effects of activator treatment on Class II malocclusion patients were evident on ramal height, body length, effective body length, ANB, and overjet. Clockwise rotation of the long axis of the Atlas was found in Group 1, but there was no inclination change of the Atlas in groups 2 and 3. There was no significant correlation between anterior and posterior positions of the atlas or morphological change in all groups. - except for posterior movements of the Atlas found in group 1. Conclusion: Clockwise rotation of the atlas axis resulted from activator treatment in Cl II malocclusion patients. Change in atlas axis can be thought of as an indicator for success of activator treatment.