• 한국지반공학회논문집
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• 제18권5호
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• pp.55-65
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• 2002

소성흐름을 발생시키는 측방유동 가능지반내에 설치된 매설관에 작용하는 토압에 대한 메카니즘을 규명하기 위해 파괴형상실험을 실시하고, 파괴형상실험을 토대로 지반변형속도를 고려하기 위해 Maxwell 점탄성 모델을 적용한 토압산정식을 제안하였다. 직접전단실험으로 구한 점성계수와 내부마찰각과 상재압을 고정하여 이론식으로 도출해낸 점성계수가 잘 일치하고 있음을 확인하였고 모형실험결과와 이론식에 의한 토압은 지반변형속도에 영향을 받으며 비교적 일치하며 지반변형이 없는 경우에도 정지토압을 받음을 알 수 있다. 또한, 지반의 지지력은 점성토에서는 관입전단파괴시의 값과 거의 일치하였다. 또한, 매설관 주변지반의 파괴모드는 매설관직경과 무관하게 지반변형속도에 영향을 받으며 작용토압은 균질한 지층의 경우 선형적으로 증가하고 조립질에 가까울수록 선형적 감소치를 보이므로 매설관주변지반의 매립재를 이용하여 매설관주변의 토압을 경감시킬 수 있음을 알 수 있다.

• Corrosion Science and Technology
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• 제17권6호
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• pp.292-300
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• 2018

The modeling of 3D finite elements based on CAD data has been used to detect sites of corrosion defects in buried pipes. The results generated sophisticated profiles of electrolytic potential and vectors of current distributions on the earth surface. To identify the location of defects in buried pipes, the current distribution on the earth surface was projected to a plane of incidence that was identical to the pipe locations. The locations of minimum electrolytic potential value were found. The results show adequate match between the locations of real and expected defects based on modeling. In addition, the defect size can be calculated by integrating the current density curve. The results show that the defect sizes were $0.74m^2$ and $0.69m^2$, respectively. This technology may represent a breakthrough in the detection of indirect damage in various cases involving multiple defects in size and shape, complex/cross pipe systems, multiple anodes and stray current.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.310-315
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• 2003

This paper presents the effect of boundary condition of failure pressure model for buried pipelines on failure prediction by using a failure probability model. The first order Taylor series expansion of the limit state function is used in order to estimate the probability of failure associated with various corrosion defects for long exposure periods in years. A failure pressure model based on a failure function composed of failure pressure and operation pressure is adopted for the assessment of pipeline failure. The effects of random variables such as defect depth, pipe diameter, defect length, fluid pressure, corrosion rate, material yield stress, material ultimate tensile strength and pipe thickness on the failure probability of the buried pipelines are systematically studied by using a failure probability model for the corrosion pipeline.

• 동력기계공학회지
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• 제13권1호
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• pp.39-45
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• 2009

The attenuation of the fundamental non-torsional modes that propagate down buried steel water pipes has been studied. The mode shapes, mode attenuation due to leakage into the surrounding medium and the scattering of the modes as they interact with pipe joints and fittings have been investigated. In the low frequency region the mode predicted to dominate over significant propagation distances approximates a plane wave in the water within pipe. The established acoustic technique used to locate leaks in buried steel water pipes assumes that leak noise propagates as a single non-dispersive mode at a velocity related to the low frequency asymptote of this water borne mode.

• International Journal of Precision Engineering and Manufacturing
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• 제4권6호
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• pp.12-19
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• 2003

This paper presents the effect of boundary conditions in various failure pressure models published for the estimation of failure pressure. Furthermore, this approach is extended to the failure prediction with the aid of a failure probability model. The first order Taylor series expansion of the limit state function is used in order to estimate the probability of failure associated with each corrosion defect in buried pipelines for long exposure period with unit of years. A failure probability model based on the von-Mises failure criterion is adapted. The log-normal and standard normal probability functions for varying random variables are adapted. The effects of random variables such as defect depth, pipe diameter, defect length, fluid pressure, corrosion rate, material yield stress, material ultimate tensile strength and pipe thickness on the failure probability of the buried pipelines are systematically investigated for the corrosion pipeline by using an adapted failure probability model and varying failure pressure model.

• 한국구조물진단유지관리공학회 논문집
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• 제20권2호
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• pp.86-93
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• 2016

본 연구에서는 토조에 설치한 관의 종류 및 매립 깊이, 공동 깊이 및 포장 조건 등에 대한 GPR(Ground Penetrating Radar) 탐사를 진행하여 매립관의 종류 및 공동 탐사 능력을 실험적으로 규명하였다. 아스팔트 포장 및 비포장의 경우, 콘크리트 포장 및 철근 콘크리트 포장 대비 매립관의 탐사가 용이한 것으로 평가되었다. 또한 공기 공동의 경우, 매립 깊이 1 m에서는 탐지가 가능한 것으로 평가되었다.

• 상하수도학회지
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• 제26권1호
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• pp.13-20
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• 2012

In this paper, we present the result of an investigation pertaining to the pipe stiffness of buried flexible pipes. Pipe stiffness (PS) formula for the parallel plate loading condition is derived based on the elasticity theory. Vertical and horizontal displacements are also derived. Vertical deflection is always larger than the horizontal deflection because some of energy due to overburden load is stored in the pipe but the difference is negligibly small. In the study, mechanical properties of the flexible pipes produced in the domestic manufacturer are tested and the results are reported in this paper. In addition, pipe stiffness is determined by the parallel plate loading tests and the finite element analysis. The difference between test and analysis is less than 14% although there are significant variations in the mechanical properties of the pipe material. Therefore, it was found that the finite element analysis can be used to predict the pipe stiffness instead of conducting parallel plate loading test.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 춘계 학술발표회 초청강연 및 논문집
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• pp.553-562
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• 2008

A remediation technique for buried pipeline system subject to permanent ground deformation is proposed. Specifically, EPS (expanded polystyrene) geofoam blocks are used as low density backfill, thereby reducing soil restraint and pipeline strains. In order to evaluate this remediation technique, a series of 12 centrifuge model tests with HDPE pipe were performed. The amount or spatial extent of the low density backfill was varied, as well as the orientation of the pipe with respect to the fault offset. Specifically, in the $-63.5^{\circ}$ test, the orientation was such that the pipe was placed in flexure and axial tension. The $-85^{\circ}$ orientation placed the pipe mainly in flexure. In all cases, the behavior of the remediated pipe was compared to that for the unremediated pipe. The geofoam backfill was successful in improving pipe behavior for two of the three pipe/fault orientations. However, for the $60^{\circ}$ orientation, the pipe buckled in compression irrespective of the geofoam backfill.

• 상하수도학회지
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• 제32권5호
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• pp.435-443
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• 2018

Most of aged water supply pipes have been replaced by the open cut method. However, this method has some limitations because water pipes, in many cases, are buried together with other underground facilities or are buried in the middle of high-traffic roads or in narrow alleyways where boring machines cannot be used. This research developed a pipe bursting device for small diameter pipes that enables pipe replacement without excavating the ground, by the busting of existing buried pipes followed by the traction and insertion of new pipes. As a results of examining the field applicability of the developed device, PE pipes and PVC pipes required the tractive force of 413.65~665.69 kgf and 457.43~791.35 kgf respectively, plus an additional 30 % tractive force per elbow. The proper number of bursting head was demonstrated that the connection of more than 2 heads could secure a stable bending radius of 15D. The developed device can be improved through field experiments involving various pipe types and pipe diameters, as well as presence/absence of elbow, so as to be utilized regardless of diverse variables according to the conditions of the soils surrounding existing pipes.

• 한국가스학회지
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• 제27권4호
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• pp.19-26
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• 2023

지진은 지하 구조물에 영향을 미치는 가장 중요한 재해 중 하나이다. 도시가스 지하 매설 배관은 지진 발생 시 구조물의 안전성 문제가 발생할 수 있다. 우리나라는 디지털 관측을 시작한 이래로 지진 발생 횟수가 꾸준히 증가하고 있다. 도시가스배관의 내진 설계 기준은 2008년에 KGS GC204 가스배관 내진설계 기준이 제정되었지만 이는 배관 설치 시 기준으로 지진 발생 시 배관의 영향을 추정하기는 어렵다. 본 연구에서는 국내에서 매설배관으로 주로 사용하고 있는 PE(폴리에틸렌관)배관과 PLP(폴리에틸렌 피복강관) 배관을 대상으로 지진 발생 시 환경 및 배관의 변수에 따른 구조해석을 수행하였다. 본 연구는 CAE(Computer Aided Engineering)를 통해 배관을 모델링하고 지반에 변위를 발생시켜 가장 취약한 매설배관의 변수를 찾고자하였다. 이 연구를 통해 토양은 탄성계수가 클 수록, 매설심도는 깊을 수록, 관경은 작을 수록, 압력은 높을 수록, PE 보다 PLP 배관이 더 지진에 영향을 많이 받는 것을 확인할 수 있었다. 이 결과를 토대로 매설 도시가스배관의 취약지점을 유추하여 지진발생 시 매설배관의 특별점검에 활용하고자한다.[1]