• Journal of the Korean GEO-environmental Society
• /
• v.17 no.12
• /
• pp.65-72
• /
• 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.

• Earthquakes and Structures
• /
• v.22 no.4
• /
• pp.431-437
• /
• 2022

One of the best choice for transportation of oil and gas at the end of rivers or seas is concrete pipelines. In this article, a concrete pipe at the end of river is assumed under the earthquake load. The Classic shell theory is applied for the modelling and the corresponding motion equations are derived by energy method. An external force induced by fluid around the pipe is asssumed in the final motion equations. For the solution of motion equations, the differential quadrature method (DQM) and Newmark method are applied for deriving the dynamic deflection of the pipe. The effects of various parameters including boundary conditions, fluid and length to thickness ratio are presented on the seismic response of the concrete pipe. The outcomes show that the clamped pipe has lower dynamic deflection with respect to simply pipe. In addition, with the effect of fluid, the dynamic defelction is increased significantly.

• Earthquakes and Structures
• /
• v.22 no.5
• /
• pp.439-445
• /
• 2022

One of the best choice for transportation of oil and gas at the end of rivers or seas is concrete pipelines. In this article, a concrete pipe at the end of river is assumed under the earthquake load. The Classic shell theory is applied for the modelling and the corresponding motion equations are derived by energy method. An external force induced by fluid around the pipe is asssumed in the final motion equations. For the solution of motion equations, the differential quadrature method (DQM) and Newmark method are applied for deriving the dynamic deflection of the pipe. The effects of various parameters including boundary conditions, fluid and length to thickness ratio are presented on the seismic response of the concrete pipe. The outcomes show that the clamped pipe has lower dynamic deflection with respect to simply pipe. In addition, with the effect of fluid, the dynamic defelction is increased significantly.

• Geomechanics and Engineering
• /
• v.23 no.6
• /
• pp.523-533
• /
• 2020

The current study focuses on the effect of the end shape of steel pipe piles on installation effort and bearing resistance using the pressing method of installation under dense ground conditions. The effect of pile rotation on the installation effort and bearing resistance is also investigated. The model steel piles with a flat end, cone end and cutting-edge end were used in this study. The test results indicated that cone end pile with the pressing method of installation required the least installation effort (load) and showed higher ultimate resistance than flat and cutting-edge end piles. However, pressing and rotation during cutting-edge end pile installation considerably reduces the installation effort (load and torque) if pile penetration in one rotation equal to the cutting-edge depth. Inclusion of rotation during pile installation reduces the ultimate bearing resistance. However, if penetration of the cutting-edge end pile equal to the cutting-edge depth in one rotation, the reduction in ultimate resistance can be minimized. In comparing the cone and cutting-edge end piles installed with pressing and rotation, the least installation effort is observed in the cutting-edge end pile installed with penetration rate equal to the cutting-edge depth per rotation.

• Journal of Bio-Environment Control
• /
• v.17 no.3
• /
• pp.188-196
• /
• 2008

Single span pipe greenhouses (pipe houses) are widely used in Korea because these simple structures are suitable for construction by farmers thus reducing labor cost. However, these pipe houses are very weak and frequently damaged by heavy snow and strong wind. Pipe house is constructed by pipe fabricator, which is anchored to the ground by inserting each pipe end into ground to $30\sim40cm$, so the ground support condition of pipe end is not clear for theoretical analysis on greenhouse structure. This study was carried out to find out the suitable ground support condition needed f3r structural analysis when pipe house was designed. The snow and wind loading tests on the actual size pipe house were conducted to measure the collapsing shape, displacement and strain. The experimental results were compared with the structural analysis results for 4 different ground support conditions of pipe ends(fixed at ground surface, hinged at ground surface, fixed under ground and hinged under ground). The pipe house under snow load was collapsed at the eaves as predicted, and the actual strain at the windward eave and ground support under wind load was larger than that under snow load. The displacement was the largest at the hinged support under ground, followed by the hinged at ground surface, the fixed under ground and then the fixed at ground surface independent of displacement direction and experimental loading condition. The experimental results agreed most closely with the results of theoretical analysis at the fixed condition under ground among 4 different ground support conditions. As the results, it was recommended that the pipe end support condition of single span pipe greenhouse was the fixed under ground for structural analysis.

• Journal of Bio-Environment Control
• /
• v.4 no.1
• /
• pp.17-24
• /
• 1995

This study was carried out to make fundamental data for structural safety test of pipe- houses. Experiment on the stress distribution of pipe- houses was conducted to find suitable structural analysis model by examination of end support conditions of pipe. Besides, the loading test and the pile driving test were done to find pull-out capacity and bearing capacity of pipe on the assumption that pipe is pile foundation. For single span pipe - house, the theoretical results assuming the end support condition of pipe is fixed under ground agreed closely with the experimental results of stress distribution. On the other hand for double span pipe -house, the end support conditions of pipe were fixed support when vertical load is applied, and hinged one when horizontal load is applied. The pull - out capacity and allowable bearing capacity of the pipe portion that was buried in the grounds that were soft soil of paddy field and medium or hard soils of dry field derived from experimental results.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.24 no.10
• /
• pp.756-762
• /
• 2014

This paper dealt with numerical estimation of the pressure pulsation of the refrigerant in a suction pipe of the compressor. The behavior of the pressure pulsation was assumed to satisfy the wave equation. The boundary conditions and properties of refrigerant are necessary as input data of the simulation. The pulsating pressures at 15 points in a pipe were measured simultaneously from the pressure transducers. From the experimental data, the complex phase speed and impedance at the end of the pipe of the refrigerant were estimated using the signal processing and used as the input conditions of the numerical analysis. A commercial acoustic software was used to solve the behavior of pressure pulsation. The numerical results for the pressure pulsation in a pipe with and without expansion chamber were carried out and compared with those by experiments. Finally, numerical procedure to estimate the pressure pulsation in a pipe was established and verified.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2006.03a
• /
• pp.1334-1339
• /
• 2006

Dynamic response of buried pipelines both in the axial and the transverse directions on concrete pipe and steel pipe, FRP pipe were investigated through a forced vibration analysis. The dynamic behavior of the buried pipelines for the forced vibration is found to exhibit two different forms, a transient response and a steady state response, depending on the time before and after the transfer of a seismic wave on the end of the buried pipeline. The former is identified by a slight change in its behavior before the sinusoidal-shaped seismic wave travels along the whole length of the pipeline whereas the latter by the complete form of a sinusoidal wave when the wave travels throughout the pipeline. The transient response becomes insignificant as the wave speed increases. From the results of the dynamic responses at the many points of the pipeline, we have found that the responses appeared to be dependent critically on the boundary end conditions. Such effects are found to be most prominent especially for the maximum values of the displacement and the strain and its position.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2006.03a
• /
• pp.1340-1347
• /
• 2006

Dynamic response of buried pipelines both in the axial and the transverse directions on concrete pipe and steel pipe, FRP pipe were investigated through a free vibration analysis. End boundary conditions considered herein consist of free ends, fixed ends, and fixed-free ends in the axial and the transverse direction. Guided ends, simply supported ends, and supported-guided ends were added to the transverse direction. The buried pipeline was regarded as a beam on an elastic foundation and the ground displacement of sinusoidal wave was applied to it. Natural frequencies and mode shapes were determined according to end boundary conditions. In addition, the effects of parameters on the natural frequency were evaluated. The natural frequency is affected most significantly by the soil stiffness and the length of the buried pipelines. The natural frequency increases as the soil stiffness increases while it decreases as the length of the buried pipeline increases. Such behavior appears to be dominant in the axial direction rather than in the transverse direction of the buried pipelines.

• Journal of the Korean Society of Safety
• /
• v.25 no.4
• /
• pp.42-47
• /
• 2010

Recently, many techniques have been developed for the inspection of pipelines using guided waves. However, few researches have been made on the application of those techniques for buried underground pipes. Guided wave motions in the buried pipes are somewhat different from those of on-ground pipes which have traction-free (air) boundary condition on outer pipe walls and thus are strongly affected by the mechanical property of the surrounding soils. Therefore, it should be investigated the effect of soil properties on the guided wave behavior in buried pipe. On the other hand, the mechanical property of soil is largely depending on its moisture conditions nevertheless of other influential factors such as void ratio. In this study, the effect of moisture conditions in soils on mode attenuation of guided waves in the buried pipe is investigated. To this end, numerical study is performed to characterize mode attenuation behavior in buried pipes and the effective mode which is suitable for long range inspection is identified.