• Title/Summary/Keyword: backfill

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Evaluation of Installation Damage Factor for Geogrid with Particle Size (입도에 따른 지오그리드의 시공손상계수 산정)

  • Lim, Seong-Yoon;Song, Chang-Seop
    • Journal of The Korean Society of Agricultural Engineers
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    • v.52 no.3
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    • pp.113-120
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    • 2010
  • Reduction factor for installation damage required to calculate design strength of geogrid used in MSEW(mechanically stabilized earth wall) design is usually obtained in the field test simulating real construction condition. However, damages occurred in geogrid during backfill work are influenced by many factors such as polymer types, unit weight per area, backfill construction method and gradation of backfill material and field test considering these factors demand lots of time and costs. In this study, factors affecting installation damage are analyzed and empirical method to evaluate reduction factor for installation damage using maximum particle size in backfill material is suggested.

A Study on the Recycling of Coal Ash as Structural Backfill materials (구조물 뒷채움재로서의 석탄회 활용에 관한 연구)

  • 여유현
    • Journal of Ocean Engineering and Technology
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    • v.14 no.1
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    • pp.74-79
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    • 2000
  • The purpose of this paper is to recycle coal ash as structural backfill materials from electric power plants. Two million tons of coal ash are produced annually. The laboratory test was executed for the basic compatibility as substitution for structural backfill materials and the optimal mixture ratio(fly ash : bottom ash) was decided. In addition the model test was performed using medium scale earth pressure model with small size earth pressure cells model box data logger and some other apparatuses. Mixed coal ash and excellent backfill materials(coheisonless soil SW) were compared in the view of lateral earth pressure variation depending on wall displacement. The reduction of earth pressure when coal ash was used as a bockfill material was monitored comparing to that of cohesionless soil. the cost and environmental pollutants by treating coal ash can be reduced through developing the recycling technology.

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A study on Reinforcement Methods to Improve the Usability of the H-beam Backfill Installation Part in Top-Down Construction Method (역타공법 뒷채움재 설치 구간의 사용성 개선을 위한 보강 방안 연구)

  • Shim, Hak-Bo;Jeon, Hyun-Soo;Seok, Won-Kyun;Park, Soon-Jeon
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2021.05a
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    • pp.180-180
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    • 2021
  • Recently, structural damage and defect has occurred in the H-beam backfill installation part of Top-Down construction method. In order to secure structural safety and usability in the adjacent section of the backfilling method, It turns out that it is necessary to analyze by dividing into various cases. The H-beam backfill installation section is divided into the case of adding a vertical plate inside the slab, adding a shear stud, adding a reinforcing bar, changing the thickness of the pressure plate, and filling the H-beam backfill with mortar. Ansys modeling was performed and an appropriate solution was suggested by analysis.

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Structural Stability Study on the Location and Installation form of H-beam Backfill Applied to Top-Down Construction Method (역타공법에 적용되는 뒷채움재 위치 및 설치 형태에 대한 구조 안정성 연구)

  • Shim, Hak-Bo;Jeon, Hyun-Soo;Seok, Won-Kyun;Park, Soon-Jeon
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2021.05a
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    • pp.179-179
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    • 2021
  • Top-Down construction method is a method of connecting a beam to a column and using a strut to support earth retaining walls. This method has the advantage of reducing the process of underground construction by reducing the work of installation. Recently, there are a lot of cases of damage and defect occurring in H-beam backfill applied to Top-Down construction method and the concrete slab supporting H-beam backfill. For this, appropriate methods were suggested through finite element analysis of the position and installation form of the H-beam backfill.

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Evaluation of Installation Damage Factor for Geogrid using Maximum Particle Size of Backfill Material (뒤채움 최대입도를 이용한 지오그리드 보강재의 시공손상계수 산정 방법)

  • Kim, Kyung-Suk;Choi, Young-Chul;Kim, Tae-Soo;Lim, Seoung-Yoon
    • Journal of the Korean Geosynthetics Society
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    • v.6 no.4
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    • pp.29-37
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    • 2007
  • Reduction Factor for Installation Damage required for calculation of design strength of geogrid used in MSEW(mechanically stabilized earth wall) design is usually obtained in the field test simulating real construction condition. However, damages occurred in geogrid during backfill work are influenced by many factors such as polymer types, unit weight per area, backfill construction method and gradation of backfill material and field test considering these factors demands lots of time and costs. In this study, factors affecting installation damage are analyzed and empirical method for evaluating reduction factor for installation damage using maximum particle size in backfill material is suggested.

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Dynamic Analysis of Gravity Quay Wall Considering Development of Excess Pore Pressure in Backfill Soil (과잉간극수압 발생을 고려한 중력식 안벽구조물의 동적해석)

  • Ryu, Moo-Sung;Hwang, Jai-Ik;Kim, Sung-Ryul
    • Journal of Ocean Engineering and Technology
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    • v.24 no.5
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    • pp.39-47
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    • 2010
  • In this paper, a total stress analysis method for gravity quay walls is suggested. The method can evaluate the displacement of the quay walls considering the effect of excess pore pressure developed in backfill soils. This method changes the stiffness of backfill soils according to the expected magnitude of the excess pore pressure. For practical application, evaluation methods are suggested for determining the excess pore pressure ratio developed in the backfill soils and the backfill stiffness that corresponds to the excess pore pressure ratio. This method is important in practical applications because the displacement of the quay walls can be evaluated by using only the basic input properties in the total stress analysis. The applicability of the suggested method was verified by comparing the results of the analysis with the results of 1-g shaking table tests. From the comparison, it was found that the calculated displacements from the suggested method showed good agreement with the measured displacements of the quay walls. It was also found that the excess pore pressure in backfill soils is a governing influence on the dynamic behavior of quay walls.

Remediation of buried pipeline system subject to ground rupture using low-density backfill (경량채움재를 활용한 지반영구변위에 대한 지중관 시스템의 개량기법)

  • Choo, Yun-Wook;Abdoun, T.H.;O'Rourke, M.J.;Ha, D.
    • Proceedings of the Korean Geotechical Society Conference
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    • 2008.03a
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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.

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Experimental and Numerical Methods for Thermal Conductivity of Backfill Soils for Subsea Pipeline (해저배관 뒤채움 흙의 열전도율 산정에 관한 실험 및 수치 해석적 연구)

  • Park, Dong-Su;Seo, Young-Kyo
    • Journal of Ocean Engineering and Technology
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    • v.31 no.2
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    • pp.103-110
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    • 2017
  • The temperature of subsea pipeline, approximately as high as $100^{\circ}C$, is significantly higher than the temperature of surrounding sea water and sediment. In this reason, heat can be lost from the subsea pipeline to cause serious operation problem. Therefore it is important that the subsea pipeline must be designed to ensure that heat loss is small enough. Heat loss of unburied pipeline is higher than buried pipeline. For that purpose, trenching and backfilling system is a commonly used method for maintaining flow assurance in subsea pipeline installation. For this commonly used method, knowing thermal conductivity of backfill is essential to protect a heat loss of pipeline. This paper presents thermal conductivity of backfill soil using laboratory model test and numerical analysis for various backfill. In conclusion, it can be seen that higher the sand content of the man-made backfill sample, the higher the thermal conductivity. On the other hand, as the water content increases, the thermal conductivity becomes smaller.

Effect of poorly-compacted backfill around embedded foundations on building seismic response

  • Kim, Yong-Seok
    • Earthquakes and Structures
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    • v.3 no.3_4
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    • pp.549-561
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    • 2012
  • Many building foundations are embedded, however it is not easy to compact the backfill around the foundation especially for the deeply embedded ones. The soil condition around the embedded foundation may affect the seismic response of a building due to the weak contact between the soil and the foundation. In this paper, the response accelerations in the short-period range and at the period of 1 second (in the long-period range) for a seismic design spectrum specified in the IBC design code were compared considering perfect and poor backfills to investigate the effect of backfill compaction around the embedded foundation. An in-house finite-element software (P3DASS) which has the capability of horizontal pseudo-3D seismic analysis with linear soil layers was used to perform the seismic analyses of the structure-soil system with an embedded foundation. Seismic analyses were carried out with 7 bedrock earthquake records provided by the Pacific Earthquake Engineering Research Center (PEER), scaling the peak ground accelerations to 0.1 g. The results indicate that the poor backfill is not detrimental to the seismic response of a building, if the foundation is not embedded deeply in the soft soil. However, it is necessary to perform the seismic analysis for the structure-soil system embedded deeply in the soft soil to check the seismic resonance due to the soft soil layer beneath the foundation, and to compact the backfill as well as possible.

Stabilization of backfill using TDA material under a footing close to retaining wall

  • Arefnia, Ali;Dehghanbanadaki, Ali;Kassim, Khairul Anuar;Ahmad, Kamarudin
    • Geomechanics and Engineering
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    • v.22 no.3
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    • pp.197-206
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    • 2020
  • Reutilization of solid waste such as Tire Derived Aggregate (TDA) and mixing it with soft soil for backfill material not only reduces the required volume of backfill soil (i.e., sand-mining procedures; reinforcement), but also preserves the environment from pollution by recycling. TDA is a widely-used material that has a good track record for improving sustainable construction. This paper attempted to investigate the performance of Kaolin-TDA mixtures as a backfill material underneath a strip footing and close to a retaining wall. For this purpose, different types of TDA i.e., powdery, shredded, small-size granular (1-4 mm) and large-size granular (5-8 mm), were mixed with Kaolin at 0, 20, 40, and 60% by weight. Static surcharge load with the rate of 10 kPa per min was applied on the strip footing until the failure of footing happened. The behaviour of samples K80-G (1-4 mm) 20 and K80-G (5-8 mm) 20 were identical to that of pure Kaolin, except that the maximum footing stress had grown by roughly three times (300-310 kPa). Therefore, it can be concluded that the total flexibility of the backfill and shear strength of the strip footing have been increased by adding the TDA. The results indicate that, a significant increase in the failure vertical stress of the footing is observed at the optimum mixture content. In addition, the TDA increases the elasticity behaviour of the backfill.