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Geomechanics and Engineering
  Volume 11, Number 1, July 2016, pages 41-58
DOI: http://dx.doi.org/10.12989/gae.2016.11.1.041
 


Effect of spatial characteristics of a weak zone on tunnel deformation behavior
Chungsik Yoo

 
Abstract
    This paper focuses on the deformation behavior of tunnels crossing a weak zone in conventional tunneling. A three-dimensional finite element model was adopted that allows realistic modeling of the tunnel excavation and the support installation. Using the 3D FE model, a parametric study was conducted on a number of tunneling cases with emphasis on the spatial characteristics of the weak zone such as the strike and dip angle, and on the initial stress state. The results of the analyses were thoroughly examined so that the three-dimensional tunnel displacements at the tunnel crown and the sidewalls can be related to the spatial characteristic of the weak zone as well as the initial stress state. The results indicate that the effectiveness of the absolute displacement monitoring data as early warning indicators depends strongly on the spatial characteristics of the weak zone. It is also shown that proper interpretation of the absolute monitoring data can provide not only early warning for a weak zone outside the excavation area but also information on the orientation and the extent of the weak zone. Practical implications of the findings are discussed.
 
Key Words
    conventional tunneling; finite element analysis; absolute displacement monitoring; weak zone; deflection line; displacement ratio
 
Address
School of Civil, Architectural Engineering and Landscape Architecture, Sungkyunkwan University, 2066 Seboo-ro, Jangan-gu, Suwon, Kyounggi-do 16419, Republic of Korea.
 

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