• Title/Summary/Keyword: differential settlements

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Evaluating the recovering capacity of cracked SRSL in the landfill final cover (SRSL(Self Recovering Sustainable Liner)재의 매립지 최종복토층에서균열 손상 시 치유 능력 검토)

  • Baek, Hyun-Uk;Ha, Min-Ki;Kwon, Oh-Jung;Park, Jun-Boum
    • Proceedings of the Korean Geotechical Society Conference
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    • 2005.03a
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    • pp.1412-1419
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    • 2005
  • Preventing the infiltration of rainwater into the landfill site is the main purpose of the final cover in landfill sites. Compacted clay layer or geomembrain have been used as a conventional landfill final cover. But they have several disadvantages when damages might occur due to puncturing, differential settlement and desiccation or freeze and thaw. For this reason, as an alternative method SRSL(Self Recovering Sustainable Liner) has been developed. Adopting the precipitation reaction of two chemical material, by forming precipitates that fill the pores, and lower the overall permeability of the liner. The advantage of this method is that when fracture of the liner occurs the remaining reactants of the two layers form precipitates that fill the fracture and recover the low permeability of the liner. In this study, the recovering ability of the SRSL with a crack due to the seasonal variation or differential settlements was investigated by permeability tests. And in order to estimate the durability of the SRSL after freeze/thaw and desiccation, uniaxial compression strength tests were performed.

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Verification of Applicability of Buried GFRP Pipe through Numerical Analysis (수치해석을 통한 지중매설된 GFRP관의 적용성 평가)

  • Kim, Hongtaek;Kwon, Hyukjoon;Yoon, Myungjune;Yoon, Soonjong;Han, Yeonjin
    • Journal of the Korean GEO-environmental Society
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    • v.11 no.8
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    • pp.73-82
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    • 2010
  • The GFRP(Glass-Fiber Reinforced Plastic) pipe is designed to behave safely against the external forces and to secure stability of deformation and settlements of pipe, since it is laid under the ground. In this study, the evaluation for the pressure stability was carried out by performing the laboratory experiments to figure out the mechanical properties of Glass-Fiber Reinforced Plastic pipe, take a theoretical approach, and suggest the mechanical properties necessary for the analysis and design of GFRP. Numerical analysis is also conducted to evaluate on the field application through the comparison concerning relations between deformation and differential settlement in the GFRP and hume pipes when all and half sections are under the surcharge load.

Optimum Design of Piled Raft Foundations using Genetic Algorithm (유전자 알고리즘을 이용한 Piled Raft 기초의 최적설계)

  • 김홍택;강인규;황정순;전응진;고용일
    • Proceedings of the Korean Geotechical Society Conference
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    • 1999.10a
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    • pp.415-422
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    • 1999
  • This paper describes a new optimum design approach for piled raft foundations using the genetic algorithm. The objective function considered is the cost-based total weight of raft and piles. The genetic algorithm is a search or optimization technique based on nature selection. Successive generation evolves more fit individuals on the basis of the Darwinism survival of the fittest. In formulating the genetic algorithm-based optimum design procedure, the analysis of piled raft foundations is peformed based on the 'hybrid'approach developed by Clancy(1993), and also the simple genetic algorithm proposed by the Goldberg(1989) is used. To evaluate a validity of the optimum design procedure proposed based on the genetic algorithm, comparisons regarding optimal pile placement for minimizing differential settlements by Kim et at.(1999) are made. In addition using proposed design procedure, design examples are presented.

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Verification of Applicability of Buried GFRP Pipe through Model Test and Numerical Analysis (실내모형실험과 수치해석을 통한 지중매설된 GFRP관의 거동 특성)

  • Kwon, Hyuk-Joon;Yoon, Myung-June;Kim, Jin-Hyun;Lee, Myung-Jae;Kim, Hong-Taek
    • Proceedings of the Korean Geotechical Society Conference
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    • 2010.09a
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    • pp.1050-1059
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    • 2010
  • The GFRP(Glass-Fiber Reinforced Plastic) Pipe is designed to behave safely against the external forces and to secure stability of deformation and settlements in pipe, Since it is laid under the ground. In this syudy, the evaluation for stability was carried out by performing the preliminary numerical analysis to decide the sclae effect in case of indoor model test. As a result of, strain of laying pipes is preponderantly reviewed. Numerical analysis is conducted to evaluate on the field application through the comparison concerning relations between deformation and differential settlement in the GFRP and hume pipes.

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Vehicle/bridge interactions of a rail suspension bridge considering support movements

  • Yau, J.D.
    • Interaction and multiscale mechanics
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    • v.2 no.3
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    • pp.263-276
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    • 2009
  • This paper is intended to investigate interaction response of a train running over a suspension bridge undergoing support settlements. The suspension bridge is modeled as a single-span suspended beam with hinged ends and the train as successive moving oscillators with identical properties. To conduct this dynamic problem with non-homogeneous boundary conditions, this study first divides the total response of the suspended beam into two parts: the static and dynamic responses. Then, the coupled equations of motion for the suspended beam carrying multiple moving oscillators are transformed into a set of nonlinearly coupled generalized equations by Galerkin's method, and solved using the Newmark method with an incremental-iterative procedure including the three phases: predictor, corrector, and equilibrium-checking. Numerical investigations demonstrate that the present iterative technique is available in dealing with the dynamic interaction problem of vehicle/bridge coupling system and that the differential movements of bridge supports will significantly affect the dynamic response of the running vehicles but insignificant influence on the bridge response.

Stability Analysis of Very Soft Soils Using Geotextiles: The Role of Model Test and Finite Element Analysis (토목섬유로 보강한 연약지반의 안정도 해석: 모형실험과 유한요소해석)

  • 고홍석;고남영
    • Magazine of the Korean Society of Agricultural Engineers
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    • v.36 no.1
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    • pp.39-53
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    • 1994
  • To investigate the behaviour of the embankment on very soft foundation reinforced geotex- files,the laboratory model test in order to analyze the elementary effects of geotextile reinfor- cement and the finite element program analyzing the stresses and deformations characteristics was carried out. A two-dimensional nonlinear finite element program called GEOTEXT(a modification of ISBILD) for the static analysis of embankment on very soft foundation reinforced geotextiles has been developed. Both linear and nonlinear hyperbolic stress-strain soil models are inclu- ded, and incremental and stage construction can be simulated. However, the program GEO- TEXT is not developed herein as an adaptable design tool for practicing engineer. It was found that the geotextile reinforcement significantly reduced the shear stresses in the foundation and decreased the vertical differential settlements at the top of the embank- ment. This influence was more pronounced as the tensile strength of the geotextile was increased.

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Case Studies for Anlayzing Effects of Outriggers on Gravity Load Managements (아웃리거의 중력하중 조절 효과 분석을 위한 사례연구)

  • Kang, Su-Min;Eom, Tae-Sung;Kim, Jae-Yo
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.23 no.3
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    • pp.255-266
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    • 2010
  • In high-rise buildings, an outrigger system is frequently used as a resisting system for lateral loads. Since the outriggers tie exterior columns and an interior core, exterior columns can participate in the lateral load resisting system and the structural resistance capacity can be increased. However, the outriggers contribute for controlling gravity loads as well as lateral loads. The flows of gravity loads can be changed by the members of outriggers, for the purposes of transferring loads to mega-columns, distributing gravity loads equally among vertical members of columns, walls, or piles, minimizing differential settlements in a foundation system, and so on. In this study, by computational structural analyses of high-rise buildings over 100 floors, the effects of outriggers on controlling gravity loads are analyzed. Analyses for 3-dimensional models with or without outrigger members are performed, and then the gravity load distributions in columns and piles and foundation settlements are analyzed. Also, the effects of outriggers on gravity load controls during construction stages as well as after construction are included.

Analysis of Characteristics of Connected-pile Foundations for Transmission Tower according to Changes of Load and Connection Beam Conditions in Clay (점토지반에서 하중특성 및 연결보조건에 따른 송전철탑용 연결형 말뚝기초의 특성 분석)

  • Kyung, Doohyun;Lee, Junhwan;Paik, Kyuho;Kim, Youngjun;Kim, Daehong
    • Journal of the Korean Geotechnical Society
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    • v.29 no.10
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    • pp.5-18
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    • 2013
  • The differential settlement between the foundations causes the critical damage on the transmission tower constructed in soft ground. Connected-pile foundation for transmission tower structures is an option to prevent the differential settlement. It consists of main foundations and connection beams that are placed between the individual foundations at each corner of tower. In this study, 24 model pile load tests were conducted at a construction site in jeonlabuk-do to investigate the effects of the connection beams on transmission tower foundation. In model tests, various load conditions and connection beam conditions were considered. As the test results, the displacements of connected-pile foundation differed in accordance with load directions. The settlements of connected-pile foundation decreased with the increased stiffness of connection beams, lateral load capacity decreased in accordance with load height, and the lateral load capacity on the failure criteria was similar regardless of load direction.

Wetting-Induced Collapse in Rock Fill Materials for Embankment (토공구간 성토체의 Wetting Collapse에 관한 연구)

  • Lee, Sung-Jin;Lee, Il-Wha;Im, Eun-Sang;Shin, Dong-Hoon
    • Proceedings of the KSR Conference
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    • 2007.11a
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    • pp.1287-1296
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    • 2007
  • Recently, the high speed railway comes into the spotlight as the important and convenient traffic infrastructure. In Korea, Kyung-Bu high speed train service began in about 400km section at 2004, and the Ho-Nam high speed railway will be constructed by 2017. The high speed train will run with a design maximum speed of 300-350km/hr. Since the trains are operated at high speed, the differential settlement of subgrade under the rail is able to cause a fatal disaster. Therefore, the differential settlement of the embankment must be controlled with the greatest care. Furthermore, the characteristics and causes of settlements which occurred under construction and post-construction should be investigated. A considerable number of studies have been conducted on the settlement of the natural ground over the past several decades. But little attention has been given to the compression settlement of the embankment. The long-term settlement of compacted fills embankments is greatly influenced by the post-construction wetting. This is called 'hydro collapse' or 'wetting collapse'. In spite of little study for this wetting collapse problem, it has been recognized that the compressibility of compacted sands, gravels and rockfills exhibit low compressibility at low pressures, but there can be significant compression at high pressures due to grain crushing by several researchers(Marachi et al. 1969, Nobari and Duncan 1972, Noorany et al. 1994, Houston et al. 1993, Wu 2004). The characteristics of compression of fill materials depend on a number of factors such as soil/rock type, as-compacted moisture, density, stress level and wetting condition. Because of the complexity of these factors, it is not easy to predict quantitatively the amount of compression without extensive tests. Therefore, in this research I carried out the wetting collapse tests, with focusing in various soil/rock type, stress levels, wetting condition more closely.

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Long-term Settlement of High Speed Railway Embankment Compacted under Dry/Wet Condition (고속철도 토공구간 쌓기 재료의 다짐함수비 조건에 따른 장기침하 특성)

  • Lee, Sung-Jin;Lee, Il-Wha;Lee, Jin-Uk
    • Proceedings of the Korean Geotechical Society Conference
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    • 2008.10a
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    • pp.1268-1277
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    • 2008
  • Recently, the high speed railway comes into the spotlight as the important and convenient traffic infrastructure. In Korea, Kyung-Bu high speed train service began in about 400km section at 2004, and the Ho-Nam high speed railway will be constructed by 2017. The high speed train will run with a design maximum speed of 300-350km/hr. Since the trains are operated at high speed, the differential settlement of subgrade under the rail is able to cause a fatal disaster. Therefore, the differential settlement of the embankment must be controlled with the greatest care. Furthermore, the characteristics and causes of settlements which occurred under construction and post-construction should be investigated. A considerable number of studies have been conducted on the settlement of the natural ground over the past several decades. But little attention has been given to the compression settlement of the embankment. The long-term settlement of compacted fills embankments is greatly influenced by the post-construction wetting. This is called 'hydro collapse' or 'wetting collapse'. This wetting collapse problem for the compressibility of compacted sands, gravels and rockfills, has been recognized by several researchers. For this wetting settlement problem, we showed the test results carried out with 4 fill materials. These tests were performed under the condition that the fill materials were inundated at the first wetting. Subsequently, in this study, we investigated the long-term settlement characteristics of the fill materials under the repeated partial wetting and rising of the ground water table happend by rainfall.

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