• Title/Summary/Keyword: Woven-geotextile

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A study on the Reduction Scheme of Sediments Deposited on a Lateral Drain Pipe in Tunnel using Centrifugal Tests (원심모형실험을 이용한 터널 측방배수관에 퇴적되는 침전물 저감방안 연구)

  • Kim, Tae-Young;Kim, You-Seok;Park, Jong-Kwan
    • Proceedings of the KSR Conference
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    • 2006.11b
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    • pp.1380-1384
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    • 2006
  • Sediments deposited on lateral drain pipes in a tunnel make lateral porous pipes clogged. Since the safety of the tunnel can be affected by this phenomenon, it requires a regular maintenance of the lateral drain pipes. In this study, a series of centrifugal tests were conducted in order to find out the method which can reduce the clogging effect considerably. Four different types of tunnel drain configurations were selected in the experiments. By analysis of sediments for each configuration, the optimum drain configuration that can minimize sedimentation of cement constituents was investigated. As a results, the existing drain configuration which uses filter concrete appear to produce much sediments. In contrast, the new drain configuration appears to be able to reduce sedimentation ratio up to almost 50% comparing with the existing one. From these observations, it may be concluded that the new drain configuration, in which the lateral porous pipes of a tunnel are surrounded by gravel layer and non-woven geotextile, has high efficiency in maintenance.

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A Comparison Between the Ballast Replacement Method & Geosynthetics-Reinforced Method for Restraint of Mud Pumping in Service Line (영업선상에서 분니 억제를 위한 자갈치환 공법과 토목섬유 보강공법 비교연구)

  • Choi, Chan-Yong;Lee, Jin-Wook;Kim, Dae-Sang
    • Journal of the Korean Geosynthetics Society
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    • v.6 no.4
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    • pp.21-28
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    • 2007
  • 3 years visual inspection has been performed on the railway lines where ballast replacement or geosynthetics-reinforcement had been used to restrain the mud pumping. The result indicates that geosynthetics-reinforcement is more effective than ballast replacement for the long-term mud pumping. In addition, the non-woven geotextile to be used for mud pumping restraint is effective when its weight is $330N/m^2$ or above. Furthermore, the lateral tensile strain under ballast on which wheel load applies ranges from 0.016 to 0.1211% and it's 10 times larger than the lateral tensile strain which ranges from 0.0078 to 0.0385%.

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Characteristics of Settlement for Non-woven Geotextile through Cyclic Loading Model Test (보강재의 강성도를 고려한 연약지반 표층처리공법 지지력 산정방법에 관한 연구)

  • Ham, Tae-Gew;Seo, Se-Gwan;Cho, Sam-Deok;Yang, Kee-Sok;You, Seung-Kyong
    • Journal of the Korean Geosynthetics Society
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    • v.8 no.2
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    • pp.11-20
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    • 2009
  • This study, as basic research which was intended to develope the surface reinforcement method using reinforcement material which is applicable to very soft ground in Korea, was aimed at proposing the design parameter for the surface ground improvement method. To that end, a wide width tensile test using geotextile, geogrid and steel bar (substitute for bamboo) and 21 kinds of the laboratory model tests with the end restraint conditions of the reinforcement that comprises the constrained and partially constrained (3 types) conditions were conducted. Moreover, a new procedure was proposed to take into account the effect of the stiffness of Reinforce materials on bearing capacity theory of Surface Reinforcement Method for Soft Ground.

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Effects of Geosynthetic Reinforcement on Compaction of High Water Content Clay (토목섬유 보강이 고함수비 점성토의 다짐에 미치는 영향)

  • Roh Han Sung
    • Journal of the Korean Geotechnical Society
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    • v.21 no.2
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    • pp.67-84
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    • 2005
  • This research was conducted to evaluate the effectiveness of reinforcement for nearly saturated soft clay compaction. The effectiveness was investigated by roller compaction test using nearly saturated clay specimens. The nearly saturated condition was obtained by submerging clay in the water for 12 hours. High water content specimens were compacted in plane strain condition by a steel roller. A specimen was compacted by four 5 cm horizontal layers. Specimens were prepared fur both reinforced and unreinforced cases to evaluate the effectiveness of reinforcement. Used reinforcement is a composite consisted of both woven and non-woven geotextile. The composite usually provides drainage and tensile reinforcement to hi인 water-contented clay so that it increases bearing capacity. Therefore, large compaction load can be applied to reinforced clay and it achieves higher density effectively. The reinforcement also increases compaction efficiency because it reduces the ratio between shear and vertical forces during compaction process. The maximum vertical stress on the base of specimen usually decreased with higher compaction thickness. The reinforcement increases soil stiffness under the compaction roller and it initiates stress concentration. As a result, it maintains higher vertical stress level on the base of specimen that provides better compaction characteristics. Based on test results, it can be concluded that the reinforcement is essential to achieve effective compaction on soft clay.

Reinforcement of Soft Soil Subgrade for High-Speed Railroad Using Geocell (연약지반상 고속철도 노반 축조시 지오셀 시스템의 효과)

  • 김진만;조삼덕;윤수호;정문경;김영윤
    • Proceedings of the Korean Geotechical Society Conference
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    • 1999.11c
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    • pp.129-141
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    • 1999
  • This paper presents the results of plate load test and dynamic load test performed to evaluate the performance of geocell where it is used to reinforce soft subgrade for high-speed railroad. Efficacy of geocell was observed in increase in bearing capacity of subgrade and reduction of thickness of reinforced sub-ballast. Plate load tests were carried out at four different places with varying foundation soil strength as a function of number of geocell layer, type of filler material, thickness of cover soil, and the presence of non-woven geotextile. Dynamic load tests were performed in a laboratory. The test soil chamber consists of, from the bottom, 50 cm thick clayey soil, one layer of geocell filled with crushed stone, 10 cm thick crushed stone cover, reinforced sub-ballast of varying thickness, 35 cm thick ballast. This configuration was determined based on the results of numerical analysis and plate load tests. For each set of the dynamic load tests, loads were applied more than 80,000 times. One layer of geocell underlying a 10 cm thick cover soil led to an increase in bearing capacity three to four times compared to a crushed stone layer of the same thickness substituted for the geocell and cover soil layer. Given the test conditions, the thickness of reinforced sub-ballast can be reduced by approximately 35 cm with the presence of geocell.

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Field Evaluation of Scour Countermeasure Using Geobag (지오백 세굴보호공법의 현장 적용성 평가)

  • Park, Jae-Hyun;Kwak, Ki-Seok;Lee, Ju-Hyung;Chung, Moon-Kyung
    • Proceedings of the Korean Geotechical Society Conference
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    • 2006.03a
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    • pp.1251-1258
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    • 2006
  • Field evaluation of new scour countermeasure using geobag and aggregate is performed to prepare for the basis of design and construction standard in Korea. Polyester non-woven geotextile is determined as a geobag material and tire cord is used to sew up the geobag which contain aggregate. Hwasang-gyo(bridge) is selected as a pilot test site through office review and field investigation. According to the design flood of Hwasang-gyo(bridge), the size and volume of geobag are calculated and construction area and required number of geobags are computed by considering the specification of the pier and foundation of the bridge. After construction, scour depth around geobag construction area is measured and the stability of geobag is ascertained by using pole and digital camera.

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Deformation Analysis of Geosynthetic Reinforced Retaining Wall by Using Temperature Dependent Confined Tension Test Results (온도제어 구속인장시험에 의한 토목섬유 보강토옹벽의 변위해석)

  • 김홍택;방윤경;조용권
    • Journal of the Korean Geotechnical Society
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    • v.19 no.2
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    • pp.97-106
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    • 2003
  • In this study, the effect of temperature and soil confining stress on geosyntheic stress-strain properties was quantified by performing the temperature dependent confined tension tests for four types of geosynthetic including woven geotextile, composite, geomembrane and geogrid specimen. Temperature instrumentation on the GRS-retaining wall constructed in Jaechon-shi area was also performed to examine the a seasonal temperature variation of geosynthetic reinforcements in the backfill. Based on the test results, a comparison was made between unconfined and confined moduli far each temperature to quantify the soil confinement and temperature effect on stress-strain properties. And it was also proposed that the simple expressions for the secant moduli of geosynthetics as a function of temperature and confining stress on geosynthetics. As a result of the FDM analysis of GRS-retaining wall, the method of considering the effect of temperature and confining stress on geosynthetic reinforcements when performing the FDM analysis of GRS-retaining wall was proposed.