• Journal of the Earthquake Engineering Society of Korea
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• v.15 no.3
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• pp.27-35
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• 2011

Larbi (1995) and Jeong et al. (2005) analyzed the various boundary end conditions of buried pipelines using the mode superposition method as one of the dynamic analysis methods of buried pipelines. However, it is very complicated to derive calculation equations for the solutions to be obtained by this method, and even the derived calculation equations need separate computer programming for the numerical analysis in order to obtain the solutions. For this reason, this method is extremely difficult for engineers to apply in their field works. In consideration of the shortcoming of the mode superposition method, this study's purpose is to propose a 3D dynamic finite difference method, which is more easily applicable in the field. For this purpose, we tested the accuracy of the 3D dynamic analysis and compared the results with those of the mode superposition method and certified that the 3D dynamic analysis could be an alternative method to obtain the seismic responses of the pipelines.

• Journal of the Society of Disaster Information
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• v.19 no.3
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• pp.689-697
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• 2023

Purpose: The purpose of this study is to automatically extract information on underground facilities using a general-purpose smartphone in the process of applying the mini-trenching method. Method: Data sets for image learning were collected under various conditions such as day and night, height, and angle, and the object detection algorithm used the R-CNN algorithm. Result: As a result of the study, F1-Score was applied as a performance evaluation index that can consider the average of accurate predictions and reproduction rates at the same time, and F1-Score was 0.76. Conclusion: The results of this study showed that it was possible to extract information on underground buried materials based on smartphones, but it is necessary to improve the precision and accuracy of the algorithm through additional securing of learning data and on-site demonstration.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.3B
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• pp.325-335
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• 2010

The aim of this study is to survey the effects of laying drainage layer in sandy beach on beach stabilization. At first, the numerical model developed by Hur and Lee (2007), which is able to consider the flow through a porous medium with inertia, laminar and turbulent resistance terms, i.e. simulate directly WAve Structure Seabed/Sandy beach interaction and can determine the eddy viscosity with LES turbulent model in 3-D wave field (LES-WASS-3D), is validated by comparing with existing experimental data. And then, numerical simulation is carried out to examine the characteristics of wave-sandy beach interaction for a beach with/without drainage layer. From the numerical results, it is shown that mean ground-water level around a foreshore decreases and offshore-ward flow over a seabed reduces in case of a beach with drainage layer. Moreover, the effects of cross profile of drainage layer and incident wave condition on mean ground-water level around a foreshore are also discussed as well the distribution of wave setup around the foreshore.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.1
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• pp.173-180
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• 2004

This paper presents the effect of varying boundary conditions such as ground subsidence, internal pressure and temperature variation for buried pipelines on failure prediction by using a failure probability model. The first order Taylor series expansion of the limit state function incorporating with von-Mises failure criteria is used in order to estimate the probability of failure mainly associated with three cases of ground subsidence. Using stresses on the buried pipelines, we estimate the probability of pipelines with von-Mises failure criterion. The effects of varying random variables such as pipe diameter, internal pressure, temperature, settlement width, load for unit length of pipelines, material yield stress and pipe thickness on the failure probability of the buried pipelines are systematically studied by using a failure probability model for the pipeline crossing ground subsidence regions which have different soil properties.

• Proceedings of the KSME Conference
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• 2003.04a
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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.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1557-1560
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• 2003

This paper presents the effect of varying boundary conditions such as ground subsidence on failure prediction of buried pipelines. The first order Taylor series expansion of the limit state function is used in order to estimate the probability of failure associated with three cases of ground subsidence. We estimate the distribution of stresses imposed on the buried pipelines by varying boundary conditions and calculate the probability of pipelines with von-Mises failure criterion. The effects of random variables such as pipe diameter, internal pressure, temperature, settlement width, load for unit length of pipelines, material yield stress and thickness of pipeline on the failure probability of the buried pipelines are also systematically studied by using a failure probability model for the pipeline crossing a ground subsidence region.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.11
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• pp.116-123
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• 2001

A failure probability model based on Von-Mises failure criterion and the standard normal probability function is proposed. The effects of varying boundary conditions such as nearby cavity, backfill, load cycle and corrosion on failure probability of the buried pipes are systematically investigated. The location of cavity is found to affect failure probability of buried pipeline within a certain limit. It is noted that the flexibility of backfill plays a great role to change the failure probability of buried pipeline. Furthermore, the corrosion gives less effects than other boundary conditions such as cavity, load as cavity, load cycle, and backfill to the failure probability of buried pipeline.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2015.10a
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• pp.15-16
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• 2015

해저파이프라인 및 해저케이블 설치해역이 대수심으로 이동함에 따라 육지와는 다른 열악한 시공 환경에 놓이게 된다. 이때 파이프라인 및 케이블이 매설되는 해저지반 상태와 작업이 이루어지는 해역의 해상조건 등은 작업효율에 영향을 미치기 때문에 효율적인 시공이 필요하다. 본 논문은 구조물 매설에 앞서 해저지반 굴삭 작업을 수행하기 위해 ROV 트렌쳐의 하단에 장착되는 워터젯 굴삭기의 작업효율 및 시공성능 추정에 관한 연구이다. 먼저 전산유체해석을 통해 워터젯 굴삭기의 굴삭효율을 극대화할 수 있는 노즐 수량을 정하였고, 모형실험을 수행하여 굴삭기의 시공성능을 예측할 수 있는 최대 굴삭심도 및 최대 굴삭속도를 파악하였다. 이를 바탕으로 실제 운용중인 워터젯 굴삭장비들과 시공성능을 비교 분석하였다.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2010.04a
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• pp.417-420
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• 2010

지중매설관은 경우에 따라 긴 수송거리를 보이기 때문에 부식 및 충격에 의한 파손 등에 대한 모니터링이 어려운 실정이다. 이러한 조건을 극복하기 위하여 복합관 및 다중관을 설치하고 있으나, 이에 대한 연구는 아직 미비한 실정이다. 본 연구에서는 발파진동원에서 고정된 이격거리, 매설심도에서 배관 상단에 특정 진동속도를 발생시키는 발파 하중을 고려하여, 이격거리에 대한 수치해석을 수행하였으며 장약량에 따른 이격거리와 발파효율을 측정하였다. 실험값과 수치해석 값의 오차는 발파지점에서 가까울수록 크게 나타났으며 발파지점과 마주보는 방향이 반대방향보다 크게 나타났다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.5
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• pp.2368-2373
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• 2012

In this research, finite element method was carried out to evaluate the defomation of pipe and surface displacement for backfill of underground ficility. Various conditions for analysis were employer, including two different pipes(PE and concrete pipe), two different excavation depth(60cm and 150cm) and width(1.5D and 2D), a regular sand backfill, and four different flowable backfills. The vertical deformation of 60 cm diameter for PE was measured three times more than that of 30 cm diameter. The measured deformations for regular backfill and four flowable backfills were 0.320mm, and 0.135mm to 0.155mm, respectively. It ratio was around 40%. In case of 30cm diameter of concrete pipe, the measured vertical defomation was around 0.004mm for all the backfill materials. In case of installation depth, the effect of flowable backfill for flexible pipe is better than for rigid pipe. There is little effect on the deformation of concrete pipe with regular sand backfill and flowable backfill.