Tunnel System Performance Based on Different Case Histories

S.A. Mazek, S.M. Atrash

In the proceedings of: GEO2011: 64th Canadian Geotechnical Conference, 14th Pan-American Conference on Soil Mechanics and Geotechnical Engineering, 5th Pan-American Conference on Teaching and Learning of Geotechnical Engineering

Session: Buried Structures & Subsurface Systems

ABSTRACT: Development of tunneling is an effective tool to overcome high-density population challenges such as transportation and utilities activities. Tunnels are used for several purposes such as construction of sewers, railway, and roadway tunnels. The Greater Cairo Metro tunnel, El-Azhar road tunnels, and the sewage tunnel in the Greater Cairo city are considered as major projects to solve transportation and environmental problems. There are technologies to assist in excavation such as tunnel boring machine (TBM) and cut and cover method. To better understand the performance of the tunnel system, it is necessary to investigate the geotechnical problems related to tunneling. In the present study, the finite element model (FEM) is proposed to predict performance of tunnel system under shadow of three case histories. The three case studies presented and discussed in this study give good and rare opportunity to understand the performance of the tunnel system. The constitutive model for this analysis utilizes elasto-plastic materials. A yielding function of the Mohr-Coulomb type and a plastic potential function of the Drucker-Prager type are employed. A linear constitutive model is employed to represent the tunnel liner. The response of the tunnel system is described by the ground movement caused by tunneling. The ground movement is presented and calculated using the proposed 3-D FEM. The recorded measurements are also presented for the three case histories. The results obtained by the 3-D numerical model are compared with those obtained by the field measurement to assess the accuracy of the proposed 3-D numerical model. There is a good agreement between the results obtained by the 3-D FEM and those obtained by the field recording.

RÉSUMÉ: Développement de tunnel est un outil efficace pour relever les défis forte densité de population telles que les activités de transport et les services publics. Les tunnels sont utilisés à plusieurs fins, comme la construction des égouts, des chemins de fer, tunnels et routes. Le Grand Caire Metro tunnel, tunnels routiers El-Azhar, et le tunnel des eaux usées dans la ville du Grand Caire sont considérés comme de grands projets pour résoudre les problèmes de transport et l'environnement. Il existe des technologies pour aider à l'excavation comme tunnelier (TBM) et la méthode en tranchée couverte. Pour mieux comprendre la performance du système de tunnel, il est nécessaire d'enquêter sur les problèmes géotechniques liés à effet tunnel. Dans la présente étude, le modèle éléments finis (FEM) est proposé pour prédire la performance du système de tunnel sous l'ombre des trois histoires de cas. Les trois études de cas présentés et discutés dans cette étude donne l'occasion bonne et rare pour comprendre la performance du système de tunnels. Le modèle constitutif pour cette analyse utilise des matériaux élasto-plastique. Une fonction de rendement de type Mohr-Coulomb et une fonction potentiel plastique du type Drucker-Prager sont employés. Un modèle linéaire est constitutive employés pour représenter le revêtement de tunnel. La réponse du système de tunnels est décrite par le mouvement du sol causé par effet tunnel. Le mouvement de terrain est présenté et calculé en utilisant la proposition 3-D FEM. Les mesures enregistrées sont également présentés pour les trois histoires de cas. Les résultats obtenus par le modèle 3-D numériques sont comparés avec ceux obtenus par la mesure sur le terrain pour évaluer la précision du modèle numérique proposé en 3-D. Il ya un bon accord entre les résultats obtenus par le FEM 3-D et ceux obtenus par l'enregistrement sur le terrain. KEYWORDS: tunnels, numerical modelling and analysis, finite element analysis, deformations. 1. INTRODUCTION Tunneling leads to ground movement due to the associated stress change around an advancing tunnel. The numerical techniques are widely used to predict the ground movements (Berant and cambou, 1998). Finite element method is considered the most appropriate analytical technique to solve geotechnical problems (Addenbrooke and Potts, 2001; El- Nahhas, 1986; El-Nahhas et al., 1990; Karakus and Fowell, 2005; Karakus, 2007; Mazek, 2004; Mazek et al., 2006; Oettl and Hofstetter, 1998). Modeling of geotechnical properties and tunneling process is the sophisticated problem (El-Nahhas, 1986; Mazek et al., 2004). In this study, the Greater Cairo Metro tunnel, El- Azhar road tunnels, and the Greater Cairo Wastewater tunnel in central Cairo city are considered as three case studies. The tunnel system performance is studied. The tunnel system model is proposed by 3-D nonlinear finite element analysis (FEA) under the shadow of the three case histories. The aim of

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S.A. Mazek; S.M. Atrash (2011) Tunnel System Performance Based on Different Case Histories in GEO2011. Ottawa, Ontario: Canadian Geotechnical Society.

@article{GEO11Paper107,author = S.A. Mazek; S.M. Atrash ,title = Tunnel System Performance Based on Different Case Histories,year = 2011}