• 한국지반공학회논문집
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• 제29권12호
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• pp.69-75
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• 2013

지하 매설관은 우리의 일상생활과 매우 밀접하지만 일반적으로 붕괴로 인한 피해가 발생하기 전에는 그 중요성에 둔감한 편이다. 대부분의 매설관은 도로포장체 아래에 매설되어 있어 외부하중으로는 주로 교통하중을 받는다. 본 연구에서는 이러한 교통하중을 받는 지하 매설관의 거동에 대해 살펴보았다. 지하 매설관의 거동에 영향을 미치는 인자는 여러 가지가 있지만, 본 연구에서는 매설 깊이(H)와 매설관의 직경(D)의 비를 가장 중요한 인자로 보고 연구를 수행하였다. 두 가지 경우의 매설 깊이에 대한 매설관 직경 비에 따른 매설관의 건전성을 살펴보았다. 결과를 바탕으로 매설관의 건전성을 확보할 수 있는 매설깊이를 결정할 수 있었으며, 보다 경계적인 매설관 설계를 할 수 있을 것으로 기대된다.

• 한국해양공학회지
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• 제30권4호
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• pp.310-319
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• 2016

If a spoiler was attached to the pipeline investigated in a previous study, a strong flow and vortex at the lower part caused scouring and thus an asymmetric pressure distribution, which assisted in the analysis of the self-burial structure where a down force was applied to the pipe. However, only the fluid-pipe interaction was considered, excluding the medium (seabed), when practically burying the pipeline. Thus, this study applied a numerical model (LES-WASS-2D) to directly analyze the non-linear interactions among the fluid, pipe, and seabed in order to perform numerical simulations of a pipeline with a spoiler installed on the seabed. This allowed the self-burial mechanism of a pipeline with a spoiler to be analyzed in the same context as the previous study that considered only the fluid-pipe interaction. However, when a pipeline was installed on the seabed, a strong flow and vortex were found at the front of the bottom, and a spoiler accelerated the fluid resistances. This hydraulic phenomenon will reinforce the scouring and down force on the pipeline. In the general consideration of the numerical analysis results by the specifications and arrangements of the spoiler, a pipeline with a spoiler was found to be the most effective for the self-burial function.

• 설비공학논문집
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• 제26권12호
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• pp.553-558
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• 2014

Geothermal energy can be used with a geothermal heat pump or an earth-to-air heat exchange system (EAHES), which is referred to as a "cooling tube" in Korea. In this study, we suggest EAHES burial guidelines in terms of the parameters of buried pipe length and air velocity regarding the exit air temperature of EAHES. The exit air temperature for EAHES in three regions (Changwon, Busan and Seoul) was calculated with variation in buried pipe length and air velocity at ${\Phi}100mm$ and ${\Phi}200mm$. In conclusion, variation in the buried pipe length is more effective than that of air velocity to achieve the required exit air temperature.

• Ocean Systems Engineering
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• 제3권1호
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• pp.9-34
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• 2013

Submarine pipelines encounter significant wave forces in shallow coastal waters due to the action of waves. In order to reduce such forces (also to protect the pipe against anchors and dropped objects) they are buried below the seabed. The wave force variation due to burial depends on the engineering characteristics of the sub soil like hydraulic conductivity and porosity, apart from the design environmental conditions. For a given wave condition, in certain type of soil, the wave force can reduce drastically with increased burial and in certain other type of soil, it may not. It is hence essential to understand how the wave forces vary in soils of different hydraulic conductivity. Based on physical model study, the wave forces on the buried pipeline model is assessed for a wide range of wave conditions, for different burial depths and for four types of cohesion-less soils, covering hydraulic conductivity in the range of 0.286 to 1.84 mm/s. It is found that for all the four soil types, the horizontal wave force reduces with increase in depth of burial, whereas the vertical force is high for half buried condition. Among the soils, well graded one is better for half buried case, since the least vertical force is experienced for this situation. It is found that uniformly graded and low hydraulic conductivity soil attracts the maximum vertical force for half buried case. A case study analysis is carried out and is reported. The results of this study are useful for submarine buried pipeline design.

• 한국지반환경공학회 논문집
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• 제24권12호
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• pp.61-67
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• 2023

도심지 지하에 위치하며 고온, 고압조건에서 운영되는 열수송관은 파손 시 인적, 경제적으로 대규모 피해가 발생할 수 있다. 파손을 사전에 예측하기 위해 기존 파손이력과 설비이력을 분석하여 파손빈도와 상관관계를 가지는 독립변수를 도출하고, 각 변수를 활용한 단순회귀분석 변형모델이 현장에 적용되고 있다. 다만, 모델에 적용되는 독립변수간 상관관계가 클수록 변수간 독립성이 훼손되어 모델의 신뢰성이 낮아진다. 본 연구에서는 상호 연관성을 가지는 것으로 판단되는 관경, 매설깊이, 감시시스템 절연레벨, 감지선의 단선 또는 단락의 독립성을 검정하여 파손빈도 추정모델에 적용하기 위해 필요한 변수간 결합 및 범주 설정 방안을 도출하였다. 독립성 검정을 위해 연속형 변수인 관경과 매설깊이는 각각 3개의 범주, 감시시스템 절연레벨은 2개의 범주로 변환하였으며, 범주형 변수인 감시시스템 감지선 상태는 범주를 그대로 2개로 유지하였다. 독립성 검정 결과, 관경과 매설깊이간, 감시시스템 절연레벨과 감지선의 단선 또는 단락간 유의확률이 유의수준(α = 0.05)보다 작아 상호간 상관관계가 큰 것으로 나타났다. 따라서 관경과 매설깊이를 하나의 변수로 결합하고 사전에 설정한 범주를 고려하여 결합 변수의 범주는 9개로 설정하였다. 감시시스템 절연레벨과 감지선의 단선 또는 단락 역시 하나의 변수로 결합하였으며, 감지선 상태가 단선 또는 단락인 경우 절연레벨값을 신뢰할 수 없으므로 결합 변수의 범주는 3개로 설정하였다.

• Geomechanics and Engineering
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• 제8권2호
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• pp.221-235
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• 2015

A series of laboratory model tests were conducted to investigate the effects of buried pipes location on the bearing capacity of strip footing in cohesionless soil. The variables examined in the testing program include relative density of the sand, loading rate of tests, burial depths of pipe and horizontal distance of pipe to footing. The test results showed a significant increase in bearing capacities when embedment ratio of pipe and horizontal distance of pipe to footing were increased. Based on the test results, it can be concluded that the location of pipes and relative density of sand are main parameters that affect the bearing capacity of strip footing. However, loading rate has not considerable effect on bearing capacity.

• 한국지반환경공학회 논문집
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• 제17권12호
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• pp.65-72
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• 2016

There are numerous factors that affect stress distribution in a buried pipe, such as the shape, size, and stiffness of the pipe, its burial depth, and the stiffness of the surrounding soil. In addition, the pipe can benefit from the soil arching effect to some extent, through which the overburden and surcharge pressure at the crown can be carried by the adjacent soil. As a result, the buried pipe needs to support only a portion of the load that is not transferred to the adjacent soil. This paper presents numerical efforts to investigate the stress distribution in the buried concrete pipe under various environmental conditions. To that end, a nonlinear elasto-plastic model for backfill materials was implemented into finite element software by a user-defined subroutine (user material, or UMAT) to more precisely analyze the soil behavior surrounding a buried concrete pipe subjected to surface loading. In addition, three different backfill materials with a native soil were selected to examine the material-specific stress distribution in pipe. The environmental conditions considering in this study the loading effect and void effects were investigated using finite element method. The simulation results provide information on how the pressures are redistributed, and how the buried concrete pipe behaves under various environmental conditions.

• 한국환경보건학회지
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• 제40권1호
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• pp.47-54
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• 2014

Objectives: The purpose of this study is to evaluate the characteristics of leachate discharged from livestock burial sites in Gangwondo resulting from foot-and-mouth disease by monitoring the water quality at the survey tube-wells installed near livestock burial sites in order to investigate the effect of the leachate on the quality of nearby underground water and suggest a water pollution level in accordance with water quality evaluation criteria. Methods: To minimize the secondary environmental pollution damage caused by leachate at burial sites of livestock killed by foot-and-mouth disease, this study analyzed the leachate directly discharged from burial sites and installed survey tube-wells within 300 meters of livestock burial sites and investigated water quality as a means to ascertain the environmental effect of the leachate from the burial sites. In accordance with environmental management guidelines on livestock burial sites, this research investigated the water quality in the survey tube-wells in fifty five burial sites in Gangwondo. The elements investigated were $NH_3$-N, $Cl^-$, $NO_3$-N, conductivity, and E. coli. Water quality was monitored from 2011 to 2013. Results: The water quality from the drain pipe at the location of leachate from livestock burial sites showed BOD 37,209 mg/L, COD 8,829 mg/L, $NH_3$-N 3,633 mg/L, and $Cl^-$ 580 mg/L. According to the monitoring results of water quality ($Cl^-$, $NH_3$-N, conductivity) at the survey tube-wells, there was suspicion that 13 out of 55 burial sites discharged leachate, five sites discharged highly concentrated leachate (13%): one in Gangneung, one in Wonju, and three in Cheorwon. Conclusion: It was judged that out of thirteen observation wells which showed a possibility of discharged leachate, three survey tube-wells have established the discharge effect of leachate at burial sites up to recently. Therefore, it is judged that it is necessary to continue monitoring them and devise additional measures.

• 한국지반환경공학회 논문집
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• 제24권12호
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• pp.47-52
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• 2023

지역난방사업자가 운영하는 열수송관의 효율적인 유지관리를 위해 사업자가 구축한 설비이력 및 파손이력 데이터를 활용하여 파손발생과 연관성을 가지는 주요 독립변수를 확인한 후, 파손빈도와의 상관관계를 분석하고, 파손빈도 추정을 위한 기본모델을 도출하였다. 국내외 지역난방사업자가 기존에 활용 중인 사용기간 기반의 추정 모델과의 연관성을 고려하여 사용기간 뿐만 아니라 관경, 매설깊이, 감시시스템 절연레벨 등 연속형 변수와 파손빈도의 상관성이 가장 높은 독립변수로 단순회귀분석 기본모델을 제시하였으며, 나머지 독립변수는 기본모델을 수정, 보완하는 인자로 반영하였다. 분석 결과 기존 연구사례와 마찬가지로 사용기간과 파손빈도간 분석 모델의 적합성과 두 변수간 상관성이 가장 높은 것으로 확인되어 기본모델로 활용 가능하다. 관경, 매설깊이, 감시시스템 절연레벨 정보 역시 파손빈도와의 상관성이 확인되어 기본모델을 보완하기 위한 인자로 활용 가능하다.

• 한국지반공학회논문집
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• 제35권11호
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• pp.37-49
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• 2019

본 연구에서는 매립심도가 손상 하수관으로 인해 형성되는 지하 공동 및 지반함몰에 미치는 영향을 확인하기 위하여 서로 다른 심도로 지반을 조성하여 모형시험을 수행하였다. 모형시험 중에 일정 시간 간격으로 디지털 이미지를 촬영하였으며, PIV 기법을 적용하여 내부 변위 및 변형을 측정하였다. 이와 지표면에서 발생하는 지반 침하, 지하 공동의 크기 등에 대한 분석도 함께 진행하여 거동을 분석하였다. 시험 결과, 매립심도가 낮은 경우의 지반에서 매립심도가 높은 경우에 비해 지하 공동 및 지반함몰 형성에 대한 저항성이 작은 것으로 확인되었다.