• Title/Summary/Keyword: Surface settlements

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A Study on the Calculation of Lateral Flow Pressure of Polluted Soils with Various Water Contents (함수량이 다른 오염지반의 측방유동압 산정에 관한 연구)

  • 안종필;박경호
    • The Journal of Engineering Geology
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    • v.12 no.1
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    • pp.75-88
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    • 2002
  • When unsymmetrical surcharge is worked on polluted soft soils, large plastic shearing deformation such as settlements, lateral displacement, upheavals and shearing failure occured in the soils and they have often done considerable damages to the soils and structures. Accordingly, this study conducts laboratory pilots test to investigate the determination method of lateral flow pressure of polluted soft soils by comparing it to existing equations. The model test is performed that a model stock device is made and polluted soils are filled in a container which fires the soils. Then the displacement is observed as surcharge load is increased by regular intervals at untrained condition. The result shows that test the lateral flow pressure is adequately calculated by the equation (P=K$_{0}$YH) and the maximum value of lateral flow pressure Is found near 0.3H of layer thickness(H) and is higher to ground surface than synthesis pattern, Poulos distribution pattern and soft clay soils(CL, CH) which is not polluted.

Investigation of Behaviours of Wall and Adjacent Ground Considering Shape of Geosynthetic Retaining Wall (보강토 옹벽의 형상을 고려한 벽체 및 인접지반 거동 연구)

  • Lee, Jong-Hyun;Oh, Dong-Wook;Kong, Suk-Min;Jung, Hyuk-Sang;Lee, Yong-Joo
    • Journal of the Korean Geosynthetics Society
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    • v.17 no.1
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    • pp.95-109
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    • 2018
  • Recently, GRS (Geosynthetic Retaining Segmental) wall has been widely used as a method to replace concrete retaining wall because of its excellent structural stability and economic efficiency. It has been variously applied for foundation, slope, road as well as retaining wall. The GRS wall system, however, has a weak point that is serious crack of wall due to stress concentration at curved part of it. In this study, therefore, behaviour of GRS wall according to shape of it, shich has convex and concave, are analysed and compared using Finite Element analysis as the fundamental study for design optimization. Results including lateral deflection, settlements of ground surface and wall obtained from 2D FE analysis are compared between straight and curved parts from 3D FE analysis.

Analysis of Ground Movement During Diaphragm Well Panel Constructions in Sedimentary Marine Deposit (해성점토층에 실시된 지중연속벽 시공에 의한 지반의 변위 분석)

  • Lee Cheol-Ju
    • Journal of the Korean Geotechnical Society
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    • v.21 no.3
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    • pp.43-54
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    • 2005
  • The ground movements during three. full-scale trial diaphragm wall (DW) panel constructions were monitored and analysed. The DW panels were constructed in reclaimed fill where sedimentary marine deposit and residual weathered soils are being consolidated. The monitoring data showed exceptionally large lateral ground movements of up to 293 mm near a trench due to the DW panel constructions, which is about 0.8$\%$ D, where D is the maximum excavation depth. It was observed that deliberate holding period of the trench resulted in a significant increase in the lateral ground movements of about 50-225$\%$. A pre-treatment of the marine deposit by installing a single line of jet grout columns around the trench prior to the excavation was found to be a very effective way of reducing the ground movements. The measured ground settlements were compared with some relevant case histories. DW panel constructions in sedimentary marine deposit are likely to cause maximum ground surface settlement up to 0.225$\%$ D.

Assessment of Applicability of Pretentioned Soil-Nail Systems with in-situ monitoring (현장 계측을 통한 프리텐션 쏘일네일링 시스템의 적용성 평가)

  • Lee, Hyuk-Jin;Ahn, Kwang-Kuk;Kim, Hong-Taek;Bang, Yoon-Kyung
    • Proceedings of the Korean Geotechical Society Conference
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    • 2005.10a
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    • pp.320-329
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    • 2005
  • The use of diverse methods for the retaining system has been continuously increased in order to maintain the stability during excavation. However, ground anchor system occasionally may have the restriction in urban excavation sites nearby the existing structures because of space limitation. In this case, soil nailing system with relatively short length of nails could be efficiently useful as an alternative method. The general soil nailing support system, however, may result in excessive deformations particularly in excavating the zone of weak soils or nearby the existing structures. Therefore, applying the pretension force to the soil nails then could play important roles to reduce deformations mainly in an upper part of the nailed-soil excavation system as well as to improve the local slope stability. In this study, a newly modified soil nailing technology named as the PSN(Pretention Soil Nailing) is developed to reduce both facing displacements and ground surface settlements during top-down excavation process as well as to increase the global slope stability. Up to now, the PSN system has been investigated mainly focusing on an establishment of the design procedure. In the present study, the field tests including pull-out tests were fulfilled to investigate the behavior of characteristics for PSN system. All results of tests were also analyzed to provide a fundamental and efficient design.

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Analysis of the Structural Behaviours of Aluminum Tunnel Lining in Joomunjin Standard Soil by Centrifugal Model Tests (원심모형실험을 이용한 주문진 표준사 지반내 알루미늄 모형 터널 복공의 역학적 거동에 관한 연구)

  • 김택곤;김영근;박중배;이희근
    • Tunnel and Underground Space
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    • v.9 no.2
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    • pp.114-130
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    • 1999
  • It is very important to study on the structural behaviors of structurally damaged tunnel linings. A series of centrifuge model tests were performed in order to investigate different behaviors of tunnel linings. A 1/100-scaled aluminum horseshoe tunnel linings with a radius 5 cm, height 8 cm were buried in a depth with dry Joomunjin standard sand, the relative density of which was 86%. Such sectional forces as bending moments and thrusts along the tunnel circumference were measured by twelve strain gages. Earth pressures in soil mass and on the outside of lining model were estimated by pressure transducers, ground surface settlements at a center and edges by using LVDTs.

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Geovisualization of Coastal Ocean Model Data Using Web Services and Smartphone Apps (웹서비스와 스마트폰앱을 이용한 연안해양모델 예측자료의 시각화시스템 구현)

  • Kim, Hyung-Woo;Koo, Bon-Ho;Woo, Seung-Buhm;Lee, Ho-Sang;Lee, Yang-Won
    • Spatial Information Research
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    • v.22 no.2
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    • pp.63-71
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    • 2014
  • Ocean leisure sports have recently emerged as one of so-called blue ocean industries. They are sensitive to diverse environmental conditions such as current, temperature, and salinity, which can increase needs of forecasting data as well as in-situ observations for the ocean. In this context, a Web-based geovisualization system for coastal information produced by model forecasts was implemented for use in supporting various ocean activities. First, FVCOM(Finite Volume Coastal Ocean Model) was selected as a forecasting model, and its data was preprocessed by a spatial interpolation and sampling library. The interpolated raster data for water surface elevation, temperature, and salinity were stored in image files, and the vector data for currents including speed and direction were imported into a distributed DBMS(Database Management System). Web services in REST(Representational State Transfer) API(Application Programming Interface) were composed using Spring Framework and integrated with desktop and mobile applications developed on the basis of hybrid structure, which can realize a cross-platform environment for geovisualization.

A Study on Performance of Double-Core PBD for Improving Thick Reclaimed Ground (대심도 연약지반 개량을 위한 이중코어 PBD 성능연구)

  • Yang, Jeong-Hun;Hong, Sung-Jin;Lee, Woo-Jin;Choi, Hang-Seok;Kim, Hyung-Sub
    • Proceedings of the Korean Geotechical Society Conference
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    • 2008.03a
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    • pp.281-292
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    • 2008
  • Prefabricated Board Drains (PBDs) recently become more widely used than conventional sand drains in improving soft ground because the PBD is more time and cost effective. The performance of PBDs is affected by disturbance in the adjacent soil formation during inserting mandrels, the intrusion of fine particles into filter fabric, and necking of the drain by excessive lateral pressure especially occurring in very deep clay formation such as the Busan New Port site. In this study, the PBD with double-core is introduced, which seems to overcome the shortcomings of usual single-core PBDs. An in-situ test program was established in the Busan New Port site, in which a set of the double-core PBDs and the single-core PBDs was installed to compare the efficiency of each of the drains. The discharge capacity of the double-core and the single-core PBDs was compared for various confining pressures in the modified Delft test and the chamber test. A series of CRS consolidation tests was performed in order to obtain profiles of void ratio-effective stress and void ratio-permeability relationships in the Busan New Port site that are used as input date in performing a numerical program ILLICON. The numerically simulated settlements of ground surface in the test site are in good agreement with those of in-situ measurements. In addition, the performance of the double-core and single-core PBDs has been experimentally and numerically compared in this paper.

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A Study on the Concrete Lining Behavior due to Tunnel Deterioration (터널 열화로 인한 콘크리트 라이닝의 거동에 관한 연구)

  • Han, Young-Chul;Jeong, Sang-Seom
    • Journal of the Korean Geotechnical Society
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    • v.30 no.4
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    • pp.21-34
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    • 2014
  • This paper studies the time-dependent behaviors of tunnel and surrounding ground due to tunnel deterioration. In the first part, the literature on deterioration characteristics of tunnels was reviewed. In the second part, a numerical analysis was performed to investigate the behavior of concrete lining on the typical section of Korean high-speed rail tunnel (weathered rock) after determination of input variables related to deterioration impact. The result shows that the settlement at the crown of tunnel and surface ground increased up to 7.0% and 30.2% of the total settlements during construction stage, respectively, and the internal convergence reduction of 9.0 mm for concrete linings was generated within 30 years after completion of tunnel construction. Also the loosening height increased up to 2.55 times of tunnel height within 50 years, which is higher than that of Terzaghi's recommendation on ultimate state. Due to this process of extending zones, it is found that additional loads were applied to concrete lining with the axial stress about 3.20~3.66 MPa, which accelerates tunnel deterioration. Finally the quantitative design approach to evaluate time-dependent behavior of lining and surrounding ground due to tunnel deterioration was proposed.

Dynamic Properties and Settlement Characteristics of Korea Weathered Granite Soils (화강풍화토의 동적 물성치와 침하특성에 대한 연구)

  • Park, Jong-Gwan;Kim, Yeong-Uk;Lee, In-Mo
    • Geotechnical Engineering
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    • v.9 no.2
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    • pp.5-14
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    • 1993
  • Weathered granite soil is the most representative as a surface soil in Korea. In this paper, the dynamic properties and settlement characteristics of Korea granite soil are studied through the dynamic triaxial compression tests. The dynamic characteristics are very important on the analysis of the foundations under dynamic loading such as machine vibration and earthquake. Soil samples having different grain sixtes were prepared at the relative densities between 80oA and 90oA and tested to measure shear moduli and damping ratios at each level of shear strain. The measured shear moduli of weathered granite soils showed large variations according to the grain sizes, confining pressures, relative densities and shear strains. Sandy weathered granite had a little larger dynamic properties than the average values of the sand studied by Seed and Idriss. Pot the well compacted granite soils, little residual settlements occured due to dynamic loading.

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Examination of 3D long-term viscoplastic behaviour of a CFR dam using special material models

  • Karalar, Memduh;Cavusli, Murat
    • Geomechanics and Engineering
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    • v.17 no.2
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    • pp.119-131
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    • 2019
  • Time dependent creep settlements are one of the most important causes of material deteriorations for the huge water structures such as concrete faced rockfill dams (CFRDs). For this reason, performing creep analyses of CFRDs is vital important for monitoring and evaluating of the future and safety of such dams. In this study, it is observed how changes viscoplastic behaviour of a CFR dam depending the time. Ilısu dam that is the longest concrete faced rockfill dam (1775 m) in the world is selected for the three dimensional (3D) analyses. 3D finite difference model of Ilısu dam is modelled using FLAC3D software based on the finite difference method. Two different special creep material models are considered in the numerical analyses. Wipp-creep viscoplastic material model and burger-creep viscoplastic material model were rarely used for the creep analyses of CFRDs in the last are taken into account for the concrete slab and rockfill materials-foundation, respectively. Moreover, interface elements are defined between the concrete slab-rockfill materials and rockfill materials-foundation to provide interaction condition for 3D model. Firstly, dam and foundation are collapsed under its self-weight and static behaviour of the dam is evaluated for the empty reservoir conditions. Then, reservoir water is modelled considering maximum water level of the dam and time-dependent creep analyses are performed for maximum reservoir condition. In this paper, maximum principal stresses, vertical-horizontal displacements and pore pressures that may occur on the dam body surface during 30 years (from 2017 to 2047) are evaluated in detail. According to numerical analyses, empty and maximum reservoir conditions of Ilısu dam are compared with each other in detail. 4 various nodal points are selected under the concrete slab to better seen viscoplastic behaviour changes of the dam and viscoplastic behaviour differences of these points during 30 years are graphically presented. It is clearly seen that horizontal-vertical displacements and principal stresses for maximum reservoir condition are more than the empty reservoir condition of the dam and significant pore pressures are observed during 30 years for maximum reservoir condition. In addition, horizontal-vertical displacements, principal stresses and pore pressures for 4 nodal points obviously increased until a certain time and changes decreased after this time.