• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1994년도 연약지반처리위원회 봄 학술발표회 논문집 연약지반처리
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• pp.13-46
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• 1994

Artificial ground freezing methods have been applied to geotechnical construction projects for stabilizing earth materials and controlling water seepage into the ground. However, this can result in frost heaving and causes the same engineering problems as encountered with the natural freezing of soil. In natural freezing, the ground freezes from the surface downward. When artificial ground freezing is applied at a deep location, however, freezing is limited locally. The soil condition differs between them as follows: Natural freezing - unsaturated and without overburden pressure. Artificial freezing -- saturated and under overburden pressure. The authors investigated the practical application of artificial ground freezing and examined the frost behaviour of a saturated soil under overburden pressure. This paper presents the results obtained from experiments concerning frost heaving and discusses frost heaving at the freezing site.

• Geomechanics and Engineering
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• 제39권1호
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• pp.73-85
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• 2024

There is growing interest in introducing artificial ground freezing (AGF) as a method to temporarily secure unstable ground during tunnel construction. In order to efficiently operate an artificial ground freezing system, basic modeling research is needed on the changes in freezing behavior according to various soil environmental conditions as well as design conditions. In this study, a thermal-hydraulic coupled analysis was performed to simulate the artificial ground freezing process of ground containing salt water. The effect of major variables, including pore water salinity, on artificial ground freezing test performance was investigated. Additionally, an artificial neural network-based prediction model was proposed to estimate the time required to achieve the desired arch thickness. The artificial neural network model demonstrated reliable accuracy (R² = 0.9942) in predicting the time it would take to reach the desired arch thickness. Among the major input variables considered, pore water salinity appeared to be the most influential input variable, and initial soil temperature showed the least importance.

• Geomechanics and Engineering
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• 제32권3호
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• pp.293-305
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• 2023

To ensure the safety of underground infrastructures, ground can sometimes be first treated by cement slurry and then stabilized using artificial ground freezing (AGF) technique before excavation. The hydration heat produced by cement slurry increases the soil temperature before freezing and results in an extension of the active freezing time (AFT), especially when the Metro Jet System (MJS) treatment is adopted due to a high cement-soil ratio. In this paper, by taking advantage of an on-going project, a case study was performed to evaluate the influence of MJS and AGF on the ground temperature variation through on-site measurement and numerical simulation. Both on-site measurement and simulation results reveal that MJS resulted in a significant increase in the soil temperature after treatment. The ground temperature gradually decreases and then stabilized after completion of MJS. The initiation of AGF resulted in a quick decrease in ground temperature. The ground temperature then slowly decreased and stabilized at later freezing. A slight difference in ground temperature exists between the on-site measurements and simulation results due to limitations of numerical simulation. For the AGF system, numerical simulation is still strongly recommended because it is proven to be cost-effective for predicting the ground temperature variation with reasonable accuracy.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1996년도 가을 학술발표회 논문집
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• pp.148-153
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• 1996

Concrete with ground granulated blast-furnace slag can be affected by frost attack because the reaction of hydration is slow at the early age. In this study, therefore, the freezing and thawing test has been carried out to investigate the freezing and thawing resistance on concrete with ground granulated blast-furnace slag. The freezing and thawing test has been performed on concrete a blended cement, which was substituted by ground granulated blast-furnace slag with 4 kinds of ratio (non-admixture, 20%, 40% and 60%). And also tested on concrete added the AE agents to the concrete of same mix proportion to search the improvement effects about the resistance. As a result, the freezing and thawing resistance showed a tendency of reduction in proportion to the increase of the substitution ratio. For non-AE concrete, resistances of the freezing and thawing were very poor as the durability index indicated less than 5.8%. For AE concrte, resistance of the freezing and thawing were excellent as the durability index indicated more than 80.9%.

• 한국농공학회논문집
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• 제52권3호
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• pp.89-95
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• 2010

There is the freezing method as one of the ground improvement methods for excavating an underground tunnel, and due to its improved reliability, recently construction cases of applying this method into sandy soil grounds as well as cohesive soil grounds of cities have been reported. But, applying the freezing method into cohesive soil grounds could bring concerns of the expansion of the whole ground and the settlements from thawing of ground. In this study, the deformation strength characteristics of cohesive soil which received freezing and thawing hysteresis were examined using the sample collected from the site of cohesive soil ground applied with the freezing method and its structural characteristics were analyzed using an electronic microscope. And, the test with cohesive soil reconstituted from cohesive soil which received freezing and thawing hysteresis was carried out and its result was analyzed comparatively. The result of this test showed that the structure of natural clay was significantly changed due to freezing and thawing hysteresis.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 추계 학술발표회
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• pp.1218-1231
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• 2008

Recently the energy dependence of LNG resource is being increased. So the enlargement of LNG storage is constructed in the coastal area. Most of LNG tanks are constructed below the ground level, and thus the hydraulic uplift pressure could be a problem against the weight of tank structure. Specifically, the settlement of foundation soil in the LNG tank is also important in the aspect of safety. The low temperature around LNG tank is induced the ground freezing and hence increasing the soil volume and earth pressure. The additional lateral earth pressure due to ground freezing could be applied to the LNG tank. In this study, the stability of LNG storage tank was evaluated with consideration of freezing earth pressure by using computer program TEMP-W.

• 대한토목학회논문집
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• 제38권4호
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• pp.555-565
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• 2018

최근 임시 지보, 보강 및 지하수 차수와 같은 다양한 지질공학분야에서 차수 및 지반보강 공법으로 인공동결공법(artificial ground freezing method)이 적용되고 있다. 인공동결공법은 지중에 매설된 동결관 내로 냉매를 순환시켜 대상 지반에 차수벽 및 지지체의 역할을 할 수 있는 동결벽체(frozen wall)를 형성한다. 본 연구에서는 해성 점토지반(marine clay)에 대한 인공동결공법 현장실증시험을 수행함으로서 인공동결공법에 따른 해성 점토지반에서의 동결속도(freezing rate)를 평가하였다. 현장실증시험은 지중에 3.2m 깊이로 매설된 동결관 내로 초저온 냉매인 액화질소를 순환시키는 방법으로 단일공 시험과 동결벽체 형성 시험을 수행하였다. 자동밸브를 통해 유출되는 액화질소의 온도를 일정하게 유지시켰으며, 동결과정에서 동결관 외벽 및 지중의 온도변화를 측정하였다. 시험결과, 단일공 시험은 부피가 약 $2.12m^3$인 원기둥 모양의 동결체를 형성하는데 총 3.5일 동안 약 11.9ton의 액화질소가 소요되었고, 동결벽체 형성 시험은 부피 약 $7.04m^3$의 동결벽체를 형성하는데 총 4.1일 동안 약 18ton의 액화질소가 소요된 것으로 산정되었다. 임의의 깊이에서 동결면적이 동결반경의 제곱에 비례하기 때문에 동결반경이 증가할수록 방사방향 1차원 동결속도가 감소하였고, 이를 바탕으로 방사방향 1차원 동결속도 예측식을 제시하였다.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2014년도 춘계 학술논문 발표대회
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• pp.284-285
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• 2014

In this study, effects of pore structure of ground granulated blast-furnace slag concrete on freezing-thawing resistance are reviewed. As a result, degradation of freezing-thawing resistance performance was occurred as replacement ratio of ground granulated blast-furnace slag increases under same specified concrete strength condition. It is considered that pore structure of internal binder affects freezing-thawing resistance performance.

• 한국식품과학회지
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• 제21권6호
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• pp.735-741
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• 1989

For the accurate prediction of freezing time, probably the most difficult factor to measure and major error source is the surface heat transfer coefficient. In this work, surface heat transfer coefficient were determined for still air freezing and immersion freezing methods by theory of the transient temperature method and confirmed by using a modification of plank's equation to predict the freezing time of ground lean beef. The results showed the cooling rate of immersion freezing was about 11 times faster than that of still air freezing method. A comparison of surface heat transfer coefficient of copper plate and ground lean beef resulted an difference of 25-30% because the food sample surface is not smooth as copper plate. Also, when h-values measured by ground lean beef were applicated to modified model, the accuracy of its results is very high as difference of about 8%.

• 아시안잔디학회지
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• 제4권1호
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• pp.42-48
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• 1990

Experiments were conducted to investigate the soil freezing depth and pattern with freezing measuring instruments during 1988-l989 winter season in Kangwon province. Freezing measuring instrument was made with acrylic pipes which were consisted of inner and outer parts. Inner pipe was filled with 0.01 % methylene blue solution and rubber hose to protect pipe breakdown by solution freezing. Freezing measurements were carried out by observing discoloration of methylene blue solution. Moisture content of evergreen trees and ground cover plants was also examined in the winter season. The observed results are as follows: 1.In the land of I OOM above sea level, soil freezing depth became deeper as the sum of Accumulated degree-days of temperature below 0˚C(0˚C . day) increased: Soil freezing depth was 30-40cm at l00˚C, 42-43cm at 150˚C, and 47cm at 200˚C day 2.Soil freezing with vinyl mulching was less developed by l3cm at l00˚C with sum of subzero temperature, by l7cm at 200˚C than that of the bare ground. Soil of rich hulls mulching with 4Ocm was not frozen until soil freezing at the bare ground was developed to 25cm depth. 3.Cashmeron mulching was more effective than felt mulching in the heat insulation of soil. 4.Thawing of soil was done from the lowest part of the frozen in the ground to upward in the beginning and after that it was done from the surface of frozen soil to downward. Finally thawing was completed at the middle of frozen soil.