• Land and Housing Review
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• v.3 no.1
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• pp.83-88
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• 2012

In this study, physical characteristics of cement and/or concrete materials that are typically used for energy-foundation (EF) structures have been studied. The thermal conductivity and structural integrity of the cement-based materials were examined, which are commonly encountered in backfilling a vertical ground heat exchangers, cast-in-place concrete piles and concrete lining in tunnel. For this purpose the thermal conductivity and unconfined compression strength of cement-based materials with various curing conditions were experimentally estimated and compared. Hydration heat generated from massive concrete in the cast-in-place concrete energy pile was observed for 4 weeks to estimate its dissipation time in the underground. The hydration heat may mask the in-situ thermal response test (TRT) result performed in the cast-in-place concrete energy pile. It is concluded that at least two weeks are needed to dissipate the hydration heat in this case. In addition, a series of numerical analysis was performed to compare the effect of thermal property of the concrete material on the cast-in-place pile.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.6C
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• pp.231-240
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• 2011

Various pile load tests were carried out at Gwangyang district for 10 different piles in order to analyze the characteristcs of steel pile using high strength steel and high driving energy. Pile drivability results showed that PHC piles needed highest total blow count even with the shortest pile length and high strength steel pipe piles showed smallest total blow count eventhough driven to a more hard ground condition with longer pile length. Pile dynamic analysis results showed that for PHC pile and general steel pipe pile the allowable pile design load was decided by the allowable material strength but for high strength steel pipe pile the design load can be decided according to the ground bearing capacity. Static load test and load transfer test results showed that the pile design efficiency could be improved over 80% allowing lesser number of piles necessary for a more economical solution. Set-up effects was analyzed and regression equation for the site ground condition was derived. Bearing capacity was checked with widely used design equation and the limitation of current design method and future technology development on this subject is dicussed in this paper.

• Journal of the Korea Organic Resources Recycling Association
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• v.19 no.2
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• pp.41-48
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• 2011

In this study, the soil remediation by landfarming was carried out using microbial activators. Feasibility studies and reduction capacity of TPH(Total Petroleum Hydrocarbons) were investigated in order to find out how fast and eco-friendly the contaminated soil can be recovered. The lab-test confirmed not only the performance and degradation efficiency of microbial activators but also the effect of TPH reduction in the contaminated soil. The optimum growth conditions for indigenous microorganisms were identified using microbial activators. Based on the results of TPH removal, although there had been a little of difference in between natural decomposition and microbial activators until 20 days, the sample groups of microbial activators were higher than the control ones after 20 days. Microbial activators were applied to the field experiments on landfarming. Based on the results of removal rate in each floor of soil, it was found that the removal rates were 85.8 % in the upper, 84.4 % in the middle, and 66.10 % in the bottom. Considering that the reduction rate of TPH for the control group averaged 71.1%, the microbial activators might not be fully transferred into the bottom, which resulted from the piles of soil. As the piles have already reached 1 m in the field experiments, the low piles of soil under 0.6 m may enhance the treatment efficiency of TPH.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.03a
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• pp.912-921
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• 2009

Pulse-discharge technology (PDT) is an innovative technology which uses enormous energy developed by electric discharge for a very instant moment of time. Lately, it has been applied to make expanded sections at the ends of piles and anchors. The expanded section is formed by the deformation of bore-hole induced by shockwave energy developed in filling material by the pulse discharge. In this study, considering the phenomenon of pulse-discharge as an underwater explosion, finite element analyses were carried out to model the shockwave development by pulse discharge. The simulation technique was verified by comparing results with underwater discharge test results.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.6 no.1
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• pp.23-28
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• 2010

The objective of this study is to develope ground heat exchanger using PHC pile used to building foundation, and it's element technology. So we made PHC piles into ground heat exchanger and evaluate it's performance. First, we studied PHC pile type, heat exchanger pipe, grouting materials, and present apartment house's foundation condition for PHC ground heat exchanger. As a result we designed BIGS(Building Integrated Geothermal System) prototype. Second, we applied BIGS to apartment houses' utility building in Osan built by Daelim. Third, we monitored heating performance of winter season. 1be result of heating performance was so good to apply to heat & cooling system in building.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.19 no.3
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• pp.387-419
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• 2021

The challenges facing companies and institutions surrounding civil nuclear decommissioning are diverse and many, none more so than those faced in the United Kingdom. The UK's Generation I nuclear power plants and early research facilities have left a 'Nuclear Legacy' which is in urgent need of management and clean-up. Sellafield is quite possibly the most ill-famed nuclear site in the UK. This complex and challenging site houses much of what is left from the early days of nuclear research in the UK, including early nuclear reactors (Windscale Piles, Calder Hall, and the Windscale Advanced Gas Cooled Reactor) and the UK's early nuclear weapons programme. Such a legacy now requires careful management and planning to safely deal with it. This task falls on the shoulders of the Nuclear Decommissioning Authority (NDA). Through a mix of prompt and delayed decommissioning strategies, key developments in R&D, and the implementation of site licenced companies to enact decommissioning activities, the NDA aims to safety, and in a timely manner, deal with the UK's nuclear legacy. Such approaches have the potential to influence and shape other such approaches to nuclear decommissioning activities globally, including in Korea.

• Journal of the Korean Geotechnical Society
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• v.36 no.7
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• pp.15-28
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• 2020

As the skin friction of an embedded pile is produced by the cement paste injected into the borehole, the skin friction cannot be evaluated by the end of initial driving test, which is conducted before the cement paste is cured. In addition, the total resistance of an embedded pile may not be properly evaluated during the restrike test if the base resistance is not fully mobilized because of the insufficient driven energy. The objective of this study is to suggest a new load-settlement curve of embedded piles by combining the results of the end of initial driving and restrike tests. Test piles are installed at fields by using the embedded pile method, and the results of the dynamic pile tests are analyzed using CAse Pile Wave Analysis Program (CAPWAP) after the end of initial driving and restrike tests are conducted. A new load transfer curve, which combines the behaviors of the pile base at the end of initial driving and of the pile shaft at the restrike, is suggested, and a new load-settlement curve is obtained. Subsequently, the resistances of the test piles are evaluated using the combined load-settlement curve, and compared with the results from the end of initial driving and restrike tests. The results showed that the resistances, which are evaluated using the combined load-settlement curve, may overcome the underestimation of the resistance because of the insufficient driven energy. In addition, the resistance resulted from the combined load-settlement curve may be more similar to that from the static load test because the suggested load transfer curve is closer to the behavior of the embedded pile compared to the results of end of initial driving and restrike tests. Therefore, this study demonstrates that the combined load-settlement curve may be effectively used for the evaluation of the bearing capacity of embedded piles.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.36 no.1
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• pp.31-38
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• 2016

In this paper, the deformation-energy curves of the plastic hinges and the vessel bow, which are the major energy dissipation mechanism of a pile protective structures, were estimated, and the parametric study was performed by using those curves to apply the simplified collision model which developed in the previous study. Considered parameters were the mass of slab, the number of piles, the mass of vessel and the collision speed. As results, the difference of energy dissipation mechanism of two pile types (filled and non-filled) were revealed, and the collision behaviors of the protective structures could be tuned by the control of the inertia mass of capping slab. Therefore the simplified collision model can be used in a primary design and optimal design.

• Land and Housing Review
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• v.11 no.2
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• pp.87-94
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• 2020

Offshore renewable energy resources are attractive alternatives in addressing the nation's clean energy policies because of the high demand for electricity in the coastal region. As a large portion of potential resources is in deep and farther water, economically competitive floating systems have been developed. Despite the advancement of floating technologies, the high capital cost remains a primary barrier to go ahead offshore renewable energy projects. The dynamically installed piles (DIPs) have been considered one of the most economical pile concepts due to their simple installation method, resulting in cost and time-saving. Nevertheless, applications to real fields are limited because of uncertainties and underestimated load capacity. Thus, this study suggests the appropriate analytical approach to estimate the inclined load capacity of the DIPs by using the upper bound plastic limit analysis (PLA) method. The validity of the PLA under several conditions is demonstrated through comparison to the finite element (FE) method. The PLA was performed to understand how flukes, soil profiles, and load inclinations can affect the inclined load capacity and to provide reliable evaluations of the total resistance of the DIPs. The studies show that PLA can be a useful framework for evaluating the inclined load capacity of the DIPs under undrained conditions.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.14 no.4
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• pp.965-975
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• 1994

Opening the tip of a PHC pile, under a constant driving energy, can result in an increment of penetration depth due to the decrement of driving resistance. Therefore, the bearing capacity of an open-ended PHC pile may become larger than that of a closed-ended PHC pile by virtue of the increased embedded length. However, two main problems can be caused by opening the end of PHC pile. First problem is the variation of bearing capacity by opening the pile tip, and the second one is whether the tip of an open-ended PHC pile will be failured by a high pressure developed by the soil plug. In this study, model pile tests in calibration chamber were performed to investigate the practicability of open-ended PHC pile in view of both the pile bearing capacity and the possible failure of the pile tip. According to the test results, the total bearing capacity of open-ended piles approaches the total bearing capacity of closed-ended piles with the increase of the penetration depth. The failure of pile tip could be occurred in the region of 0.8~1.1 times as the inside diameter from the pile tip.