• Title/Summary/Keyword: Measured tunnel convergence

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Geotechnical parameter estimation in underwater tunnel using relative convergence measurement (하저터널에서 상대내공변위 계측을 통한 지반정수 예측)

  • Kim, Do-Hoon;Jang, Jea-Hyuck;Lee, In-Mo
    • Proceedings of the Korean Geotechical Society Conference
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    • 2008.03a
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    • pp.792-802
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    • 2008
  • If a tunnel is constructed below the groundwater level, the groundwater flow will occur inducing the seepage force toward the tunnel and will result in the increase of tunnel convergence. The longitudinal deformation during tunnel excavation will also be increased due to seepage pressure. A back-analysis methodology in underwater tunnel was proposed in this study based on the relative longitudinal deformation measured in-situ. Geotechnical parameters can be estimated utilizing the proposed method where the prior estimate as well as the measured convergence can be reasonably combined by adopting the Extend Bayesian Method.

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Estimation of Tunnel Convergence Using Statistical Analysis (통계처리를 활용한 터널 내공변위의 분석에 관한 연구)

  • 김종우
    • Tunnel and Underground Space
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    • v.13 no.2
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    • pp.108-116
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    • 2003
  • Measured convergence data of a tunnel were investigated by means of statistical and regression analysis, where the rock mass were mainly composed of andesite and granite. The rock mass around tunnel were classified by RMR method into five different ratings, and then convergence data which belong to individual ratings were statistically processed to find out the appropriate regression equations. Exponential equations were better coincided with measured data than logarithmic equations. As the number of rock mass rating was increased, the magnitude and standard deviation of convergence were increased. Final convergence data were also investigated to study the relevance with both maximum displacement rate and early measured convergence. Some brief results of their relevance are presented. For instance, the regression coefficient between final convergence and maximum displacement rate was turned out to be 0.87 for this studied tunnel.

Relations between Initial Displacement Rate and Final Displacement of Arch Settlement and Convergence of a Shallow Tunnel (저심도 터널의 천단침하 및 내공변위의 초기변위속도와 최종변위의 관계)

  • Kim, Cheehwan
    • Tunnel and Underground Space
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    • v.23 no.2
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    • pp.110-119
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    • 2013
  • It is generalized to measure the arch settlement and convergence during tunnel construction for monitoring its mechanical stability. The initial convergence rate a day is defined from the first convergence measurement and the final convergence defined as the convergence measured lastly. The initial and the final tunnel arch settlement are defined like the preceding convergence. In the study, the relations between the initial and final displacements of a shallow tunnel are analyzed. The measurements were performed in the tunnel of subway 906 construction site in Seoul. The overburden is 10-20 m and the tunnel goes through weathered soil/rock. The width and height of the tunnel are about 11.5 m, 10m, respectively. So this is a shallow tunnel in weak rock. The length of tunnel is about 1,820 m and the tunnel was constructed in 2 stages, dividing upper and lower half. The numbers of measurement locations of arch settlement and convergence are 184 and 258, respectively. As a result, the initial displacement rate and the final displacement are comparatively larger in the section of weathered soil.

Development of Underground Displacement and Convergence Auto-Measuring Program for the Tunnel Using the Fiber Optic Sensor (광섬유 센서를 이용한 터널 지중 및 내공변위 자동계측 프로그램 개발)

  • Choi, Myong-Ho;Yoon, Ji-Son;Kwon, Oh-Duk;Kwon, Oh-Jun
    • Proceedings of the Korean Geotechical Society Conference
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    • 2005.03a
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    • pp.1361-1368
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    • 2005
  • In this paper, the theoretical method of measuring the tunnel convergence and underground displacement, the objective indices of assessing safety for tunnel construction, using the fiber optic sensor is studied by developing the program to automatically measure them. The model test of Con'c beam is conducted to evaluate reliability of the fiber optic sensor. Furthermore, using the RS232 communication protocol as well as Visual C# and Visual C++, the programming tools, the program was developed to detect automatically the measured value of the fiber optic sensor, calculate the tunnel convergence and underground displacement, predict the deformed shape of the tunnel, and evaluate loosening zone due to the tunnel excavation.

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Analysis for Measuring Displacement of Tunnel Face using Horizontal Inclinometer (터널 시공 중 수평경사계를 이용한 변위 분석)

  • Jang, Won-Yil;Yang, Hyung-Sik;Chung, So-Keul
    • Tunnel and Underground Space
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    • v.17 no.5
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    • pp.428-434
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    • 2007
  • Displacement of tunnel face is important issues for the evaluation of tunnel safety. In this study, conventional convergence and displacement data measured from horizontal inclinometer were analyzed to investigate the trend and characteristics of tunnel deformation during construction. Trend of measured displacement agreed with general understanding of tunnel deformation prior to excavation. It shows that displacement measured from horizontal inclinometer can be used to preestimate the total deformation of tunnel.

Study on the Convergence of the NATM Tunnel Constructed in the Weathered Granite (풍화 화강암 지반에 건설된 NATM터널에서의 내공변위 연구)

  • Shin, Sang-Sik;Kim, Hak Joon;Bae, Gyu Jin
    • Tunnel and Underground Space
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    • v.25 no.6
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    • pp.515-526
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    • 2015
  • Predicting and measuring tunnel convergence is very crucial for estimating tunnel stability and economical construction of NATM tunnels. The method to estimate the tunnel convergence that occurs before and after construction is proposed based on literature reviews. The total displacement occurring related to tunnel construction is determined to be about 2.5 times that of measured displacements. The results of displacement measurements at two tunnels constructed with similar rock types are examined for the investigation of factors affecting the tunnel convergence. The average convergence of Gyungju A Tunnel is about 6.7 times bigger than that of Daejeon B Tunnel. The possible causes of the large convergence in Gyungju A Tunnel are suggested. In order to predict the convergence of tunnels, careful investigation of the geological structures in the ground surface and the influence of external conditions as well as careful face mapping of the tunnel face should be conducted.

Forecasting Final Displacement With Displacement Functions Using Deformation Measurements While Constructing a Tunnel (계측치와 변위함수에 의한 시공 중인 터널의 최종변위 예측)

  • Kim, Chee-Hwan
    • Tunnel and Underground Space
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    • v.20 no.6
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    • pp.408-420
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    • 2010
  • It is important to forecast the final deformation of a tunnel during construction for evaluating its mechanical stability. In this study, the final deformation of a tunnel is forecasted by fitting tunnel deformations measured while excavating to a displacement function and exterpolating it. The tunnel for the study was built in two stages divided into an upper and a lower part. During the lower part construction of the tunnel, the displacement function forecasts the final incremental displacement well compared to the increment measured after completion of the tunnel. It is because the critical initial displacement occurred on passing the measurement pins can be adequately measured during excavating the lower part, which can not be measured during the upper part excavation of the tunnel.

Estimation of Final Deformation of Hard Rock Tunnel Using Early Measured Deformation (초기계측치를 이용한 경암 지반내 터널의 최총변위량 예측)

  • 송승곤;양형식;임성식;정소걸
    • Tunnel and Underground Space
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    • v.12 no.2
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    • pp.99-106
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    • 2002
  • To use the early measured data of tunnel deformation in but analysis, the relationship between these values find final deformation data were studied. Panet\`s exponential and fraction equations successfully approximate the convergence of the hard rock tunnels. Measured deformation data of ID location, $U_{1D}$ show that they can be lilted to linear equations but should not be used to estimate potential deformation before measurement, $C_{0}$. Early measured data $U_{1D}$ $U_{2D}$ , and final deformation $ U_{L}$ showed linear correlations. It proved that estimated data of final deformation from early measured ones can be used as input parameters for back analysis.

A Numerical Analysis Study for the Prediction of Convergences and Characteristics of Subsidence behavior in Shallow, Wide Tunnel Excavation (천층 광폭터널의 내공변위 및 침하거동특성 예측을 위한 수치해석적 연구)

  • 문승백;송승곤;양형식;전양수;한공창
    • Tunnel and Underground Space
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    • v.11 no.1
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    • pp.20-29
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    • 2001
  • Final convergence of tunnel crown due to excavation have been well predicted by regression analysis which is expressed as a function of convergence curve on a time and distance dependent. In this study, the validity of the equations for shallow, wide tunnel was investigated by measurement and numerical analysis. Studied tunnel(Sansoo Tunnel) is located at the boundary of downtown and mountain park. Exponential predictions equation was better coincided with measured data than fractional equation for studied tunnel, although the ground was expected to be elasto-plastic. This is because weathered rock ground is changed elasto-plastic ground into elastic ground by multi-steel grouting and forepoling.

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A study on the relationship between initial and final convergence in NATM tunnels (NATM 터널 굴착시 초기 내공변위와 최종 내공변위의 상관관계 연구)

  • Kim, Bum-Joo;Hwang, Young-Cheol
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.10 no.3
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    • pp.233-243
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    • 2008
  • A tunnel behavior predicted in the investigation and design stage is often different from its actual behavior due to mainly the complexity of ground conditions. In a tunnel construction, therefore, it is necessary to ensure the stability of the tunnel by predicting the behaviors of the ground and the supports through observations and measurements, and modifying immediately excavation and reinforcing methods when necessary. To do so, it is important to be able to predict the final tunnel behavior based on the initial tunnel behavior as early as possible. In this study, the correlations were obtained between the initial and the final convergence by analyzing statistically the convergence measurement data, collected from two domestic road tunnels under construction using NATM. In order to estimate the unknown displacements, occurred during the period between the excavation and the first measurement, two methods were used - one is the method by means of regression analysis using a modified exponential function and the other the method by a simple linear regression analysis using the data measured within the distance from tunnel face equal to the tunnel diameter (D). Finally, the relationships were obtained between the initial and final convergence, including the non-measured displacements estimated from the two different methods, by performing linear regression analyses. The regression analysis results showed that there are clear linear relationships between the initial and final convegence and the difference between the two linear regression equations was not that large for when using the exponential function and the simple linear function to estimate the non-measured displacements.

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