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The influence of buildings and ground stratification on tunnel lining loads using
finite element method
L'influence des bâtiments et de la stratification du sol sur les charges de revêtement du tunnel
utilisant la méthode d’éléments finis
Rezaei A.H.
Ph.D. student, Faculty of Civil Engineering, University of Tabriz, Tabriz, Iran
Katebi H., Hajialilue-Bonab M.
Associate Professor, Faculty of Civil Engineering, University of Tabriz, Tabriz, Iran
Hosseini B.
M.Sc in Geotechnical Engineering
ABSTRACT: Urban development and increasingly growth of population have been accompanied by a considerable growth in
mechanized Shield tunnelling. Commonly precast concrete segments used as tunnel lining in mechanized tunnelling and include
relatively considerable part of tunnelling cost. The optimum design of lining that decreases tunnelling cost needs to accurate
evaluation of loads act on lining. In this study, the effects of soil stratification, building’s geometry, position and weight on lining
loads were studied. A 2D finite element model was applied to simulate the conventional procedure of tunnel excavation and lining
using Abaqus software (Ver 6.10). The geometry of tunnel, lining segments, injection grout and around soil properties were adapted
from under construction Tabriz urban railway line 2 project. The results show that ground stratification and building properties
(especially the position of buildings) have considerable effects on lining loads. From the viewpoint of structural design, the buildings
effect on lining is critical when the surface buildings are unsymmetrical.
RÉSUMÉ : Le développement urbain et de plus en plus la croissance de la population s'est accompagnée d'une croissance
considérable dans le domaine de Tunnelier. Communément préfabriqué segments de béton utilisés comme revêtement de tunnel en
tunnel mécanisé et inclure une partie relativement importante du coût tunnel. La conception optimale du revêtement qui diminue les
coûts tunnel besoins d'une évaluation précise des charges agir sur la revêtement du tunnel. Dans cette étude, les effets de la
stratification du sol, la géométrie du bâtiment, la position et le poids des charges de revêtement ont été étudiés. Un modèle par
éléments finis 2D a été utilisé pour simulation de la procédure classique d'excavation du tunnel et revêtement en utilisant le logiciel
Abaqus (version 6.10). La géométrie du tunnel, voussoirs, coulis d'injection et autour des propriétés du sol ont été adaptées au tunnel
de métro de Tabriz (line 2) qui est en cours de construction. Les résultats montrent que la stratification du sol et les propriétés de
construction (en particulier la position des bâtiments) ont des effets considérables sur les charges de revêtement. Du point de vue de la
conception structurelle, l'effet bâtiments sur le revêtement est essentiel lorsque les bâtiments de surface ne sont pas symétriques.
KEYWORDS: FEM, Abaqus, mechanized tunnelling, tunnel lining loads, surface buildings, stratification.
1 INTRODUCTION
Urban development and increasingly growth of population have
been accompanied by a considerable growth in tunnel
construction for subways, railway underpasses, and urban
highways and a continuous development of tunneling
technology in recent years. Besides conventional excavation
methods such as the New Austrian Tunneling Method (NATM)
shield tunneling is now a well established method which allows
for tunnel advances in a wide range of soils and difficult
conditions such as high ground water pressures, soft soils or
small cover depths. It is well known that segments’ production
cost accounts for a large amount of the total shield tunnel
construction cost and one of the effective methods to reduce this
cost is to design the segments more efficiently.
In the usual design method the earth pressure acting upon the
segment lining is calculated by the overburden pressure or
Terzaghi’s loosening earth pressure according to the stratum
condition and the overburden height (Official Report of the
International Tunnelling Association 2000). In this method only
the weight of surface buildings are considered as a uniform
surcharge pressure. Nowadays, the modern shield technology
equipped with precise pressure control system at cutter face and
simultaneous backfill grouting system makes it possible to build
a tunnel without loosening the surrounding ground. Therefore,
the actual earth pressure cannot be correctly predicted by
conventional methods (Hashimoto et.al 2002).Some of the field
measurement results have shown that the loads acting on the
tunnel lining adopted in the design might be greater than the
actual loads, particularly in case of good ground conditions
(Mashimo and Ishimura 2003).
The effect of soil layering on the ground response to
tunnelling has been investigated by several researchers (Grant
and Taylor 2000). The focus of these studies has been on
tunnelling induced settlement and stability of the ground above
the excavated tunnel. In comparison with ground movements,
little attention has been paid to the effects of the overlying strata
on the stresses developing in the tunnel lining. Therefore, more
study about evaluation of loads act on lining is required and the
insights obtained from this study can contribute to an
improvement of load consideration in shield lining design. The
objective of this study is to investigate the influence of surface
buildings and ground stratification on lining loads.
In engineering practice different methods are often used to
calculate lining stresses (Nunes and Meguid 2009).In this study,
a 2D finite element model is applied to simulate the
conventional procedure of tunnel excavation and lining
installation stages properly. The geometry of tunnel, lining
segments, injection grout and surrounding soil properties were
adapted from under construction Tabriz urban railway line 2
project.
2 NUMERICAL MODELLING
Tunneling is often modelled two-dimensionally although it is a
three-dimensional (3D) problem since a full 3D numerical
