• Title, Summary, Keyword: 지표침하

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A Study on the Prediction of Surface Subsidence Zone through the Case Studies on Mined-out Area (채굴적에 의한 지반침하 사례 분석을 통한 침하발생 범위의 추정에 관한 연구)

  • Kim, Byung-Ryeol;Lee, Seung-Joong;Choi, Sung-Oong
    • Tunnel and Underground Space
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    • v.23 no.1
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    • pp.31-41
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    • 2013
  • Graphical method has been widely applied to the prediction of subsidence area, and is known to have advantages in analysis of trough subsidence which is common in horizontally seamed mine area. However, it is reported that most of the ore bodies in Korea are geologically inclined from sub-horizontal to steep, and therefore, the sinkhole subsidence is frequent in abandoned mine area. For these reasons, it is not to be desired that graphical method is applied for predicting the subsidence occurrence. This paper describes the results of subsidence zone prediction considering the dip direction and the opposite direction of inclined ore bodies from the case studies on the 163 subsidence occurrence regions. The results show also the assumed angle which can define the range of subsidence in the surface area. In conclusion, the limit of this angle is suggested after taking into account the comparison with graphical method and the application to the case histories.

Characteristics of Subsidence above a Shallow Tunnel Excavated in Weathered Rock Mass (풍화암반 저심도 터널 굴착 중 발생한 지표침하의 특성)

  • Kim, Chee-Hwan
    • Tunnel and Underground Space
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    • v.23 no.5
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    • pp.337-346
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    • 2013
  • The characteristics of subsidence above a shallow tunnel excavated in weathered rock mass is analyzed. The tunnel is excavated minimum about 11m beneath some buildings and the width of the tunnel is 11m, too. Subsidence pins are installed at 23 locations on surface along the tunnel, 180m long, adjacent to the buildings. Subsidences are measured for about 2 years and they are optimized to analyze three dimensional deformed ground surface, trough width parameter K and sectional volume loss of unit tunnel length Vs of the surface deformation profile.

Model for predicting ground surface settlement by field measuring and numerical analysis in shield TBM tunnel (현장계측과 수치해석에 의한 쉴드TBM 터널의 지표침하 예측모델)

  • Kim, Seung-Chul;Ahn, Sung-Youll;Lee, Song;Noh, Tae-Kil
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.15 no.3
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    • pp.271-287
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    • 2013
  • In this study, more convenient model(S-model) for predicting ground surface settlement is developed through comparing field monitoring data of the domestic subway applied shield TBM method with conventional equation & numerical analysis. Sample stations are chosen from whole of excavation section and lateral & vertical ground surface settlement characteristic with excavation are analysed. Based on analysis result, through the comparison with actual monitoring data, the model that is possible to compute maximum surface settlement and settlement influence area is suggested with assumption that lateral surface settlement forms are composed relaxed zone and elastic zone. In addition, vertical ground surface settlement patterns with excavation are similar to cubic-function and S-model with assumption that coefficients are function of tunnel diameter and depth is suggested. Consequently, the ground surface settlement patterns are significantly similar to actual monitoring data and numerical method result. Thus, as a result, when tunnels are excavated using sheild TBM through rather soft weathered soil & rock layer, prediction of ground surface settlement with excavation using convenient S-model is practicable.

A Trend of Back Ground Surface Settlement of Braced Wall Depending on the Joint Dips in Rocks under the Soil Strata (복합지반 굴착 시 암반층 절리경사 각도별 흙막이 벽체 배후 지표침하의 경향)

  • Bae, Sang-Su;Lee, Sang-Duk
    • Journal of the Korean Geotechnical Society
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    • v.32 no.11
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    • pp.83-96
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    • 2016
  • The surface settlement of the back ground of a braced wall due to the ground excavation has the great influence on the safety of the surrounding area. But it is not easy to predict the settlement of the surrounding area due to proud excavation. Estimation of the settlement of the surface ground induced by the deformation of the braced wall is performed by FEM and empirical method (Peck, Clough etc). In this research, surface settlement of the back ground braced wall depending on the joint dips in rocks during excavating the composit ground was measured at the large scale model test (standard: $0.3m{\times}0.3m{\times}0.5m$). The scale of model test was 1/14.5 and the ground was excavated in ten steps. Earth pressure on the braced wall and ground surface settlement on the back ground of a braced wall were investigated. The surface settlement during the excavation depended on the joint dips in rocks on of the ratio of rock layer. Maximum earth pressure and maximum surface settlement were masured at the same excavation step. In accordance with the increase of the rock layer dips and rock layer ratio, the ground surface settlement increased. The maximum ground surface settlement was 17 times larger at 60 degree joint dips in rocks than that of the horizontal ground conditions. And the position of the maximum surface settlement by empirical method was calculated at the point, which was 17%~33% of excavation depth. In accordance with the increase of the rock layer dips and rock layer ratio, the ground maximum surface settlement increased. The ground surface settlement of composite ground is smaller than that of the empirical.

Analysis of Perimetrical Ground Settlement Behavior for Deep Excavations in Urban Areas (도심지 깊은 굴착으로 발생하는 인접 지반 지표침하 분석)

  • 양구승;김명모
    • Geotechnical Engineering
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    • v.13 no.2
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    • pp.101-124
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    • 1997
  • Adjacent ground surface settlements by deep excavations are analyzed by field observations in the areas where excavations are performed in sandy soils or weathered soils underlain by rocks, First, the magnitude and the distribution of ground surface settlements, which are developed before main excavation activities (e. g., diaphragm wall installation and center pile installation) , are measured and analyzed. Secondly, the magnitude and the distribution of ground surface settlements by main excavation are measured and analyzed. And the results are compared with the predictions obtained by the empirical methods. Through case studies performed on the excavation sites where adjacent ground surfaces or structures are damaged by excavation activities, upper limit location of ground surface cracks are investigated.

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지하공동에 의한 지반침하 평가 연구

  • 권광수;박연준
    • Proceedings of the Korean Society for Rock Mechanics Conference
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    • pp.56-61
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    • 1994
  • 최근 국내 광산들의 잇달은 폐광과 함께 광산관리의 부재로 말미암아 여러 가지 문제가 야기되고 있다. 그중 대형재해의 불씨를 안고 있는 광해의 하나가 바로 지표침하이다. 본 연구는 이러한 지표침하 문제에 과학적이고도 합리적인 방법으로 대처하기 위하여 4개분야(지질, 탐사, 암반공학 및 안전공학) 가 공동으로 연구한 결과를 기술 하고자 한다. (중략)

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The effect of formation of spherical underground cavity on ground surface settlement : Numerical analysis using 3D DEM (구형지하공동 형성이 지표침하에 미치는 영향에 대한 3차원 개별요소해석)

  • Lee, Sang-Hyun;Lee, Hang-Lo;Song, Ki-Il
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.18 no.2
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    • pp.129-142
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    • 2016
  • The underground cavity known as one of the reasons of ground surface settlement is a discontinuous character. Therefore, it is limited to analyze with continuum analysis. In this research, The spherical underground cavity affecting the ground surface settlement is studied with Discrete Element Method. Ground properties, depth and diameter of the spherical underground cavity are chosen as factors of the spherical underground cavity and the effect of the each factor variations on the ground surface settlement is analyzed. Relative depth to the diameter of the spherical underground cavity is also studied. The result of the research suggests the basis of underground cavity collapse prediction and standard of support.

Numerical simulation for surface settlement considering face vibration of TBM tunnelling in mixed-face condition (복합지반에서 TBM 굴진 진동을 고려한 지표침하에 대한 수치모델링)

  • Kwak, Chang-Won;Park, Inn-Joon
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.17 no.3
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    • pp.333-339
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    • 2015
  • In this paper, the surface settlement resulted from the shallow TBM tunnelling has been numerically simulated. TBM tunnelling is especially used in urban area to avoid serious vibration and noise caused by explosion in NATM. Surface settlement is one of the most important problems encountered in all tunnelling and critical in urban areas. In this study, face vibration of TBM excavation is considered to estimate surface settlement trend according to TBM extrusion. The dynamic excavation forces are calculated by total torque on the TBM cutterhead in mixed-face of soil and weathered rock condition with shallow depth. A 3-dimensional FDM code is employed to simulate TBM tunnelling and mechanical-dynamic coupling analysis is performed. The 3D numerical analysis results showed that dynamic settlement histories and trend of surface settlement successfully. The maximum settlement occurred at the excavation point located at 2.5D behind the face, and the effect of face vibration on the surface settlement was verified in this study.

A study on ground surface settlement due to groundwater drawdown during tunnelling (터널 굴착시 지하수 저하로 인한 지반침하에 관한 연구)

  • Yoo, Chung-Sik;Kim, Sun-Bin
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.9 no.4
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    • pp.361-375
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    • 2007
  • This paper presents the results of investigation on tunnelling-induced ground surface settlement characteristics in water bearing ground using finite element (FE) stress-pore pressure coupled analysis. Fundamental interaction mechanism of ground and groundwater lowering was first examined and a number of influencing factors on the results of the coupled FE analysis were identified. A parametric study was then conducted on the influencing factors such as rock type, thickness of soil layer, permeability of shotcrete lining, among others. The results indicate that the tunneling-induced groundwater drawdown results in a deeper and wider settlement trough than without groundwater drawdown, and that the Error function approach does not yield satisfactory result in predicting a settlement profile. The results of analysis are summarized so that the relationship between the settlement and the influencing factors can be identified.

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Damage Assessment of Adjacent Structures due to Tunnel Excavation in Urban Areas (II) - Focused on the Variations of Building Stiffness Ratio - (도심지 터널 굴착에 따른 인접구조물의 손상평가에 관한 연구 (II) - 지상 건물의 강성비 변화를 중심으로 -)

  • 김창용;배규진;문현구;박치현;오명렬
    • Journal of the Korean Geotechnical Society
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    • v.15 no.5
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    • pp.81-98
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    • 1999
  • The influence of tunnelling on buildings has become an important issue in urban areas. The problem is an interactive one: not only do tunnelling settlements affect existing structures, but existing structures affect tunnel-induced soil movements. In order to examine the constraint of surface settlement and the degradation of building damage parameters, 3-dimensional elasto-plastic finite element analyses are peformed. Also, in this paper, the results of the parametric studies for the variations of the damage parameters due to the ground movements are presented by utilizing 2-dimensional elasto-plastic finite element models, totally 162 models. The width of a structure, its bending and axial stiffness, its position relative to the tunnel and the depth of tunnel are considered. The interaction is shown by reference to commonly-used building damage parameters, namely angular distortion, deflection ratio, maximum building settlements, maximum differential settlements and horizontal strain. By introducing relative stiffness parameters which combine the bending and axial stiffness of the structure with its width and stiffness of soil, design curves are established. These give a guide as to the likely modification of the greenfield settlement trough caused by a surface structure. They can be used to give initial estimates of likely building damage.

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