Finite Element Analysis of Ground Response due to Tunneling in Cohesionless Soil | ||
| The International Conference on Civil and Architecture Engineering | ||
| Article 14, Volume 7, 7th International Conference on Civil and Architecture Engineering, May 2008, Pages 289-298 PDF (480.8 K) | ||
| Document Type: Original Article | ||
| DOI: 10.21608/iccae.2008.45461 | ||
| Author | ||
| S. A. Mazek | ||
| Lecturer, Ph. D., Civil Engineering Department, Military Technical College. Cairo. Egypt. | ||
| Abstract | ||
| Tunneling in cohesionless soil leads to ground movement. In urban environment, the soil movement due to tunneling may affect surface or subsurface constructions. The ground movement is considered a major geotechnical challenge. The ground movements due to tunneling are predicted. In the present study, the prediction of the ground movement under the impact of the tunnel construction is highlighted and a model is proposed to study the soil structure interaction using a 2-D finite element analysis. The ground movement due to tunneling is also calculated using surface displacement equation proposed by Peck and Schmidt (1969). The surface displacement computed by the proposed model and the surface displacement equation is studied at different sandy soil types due to tunneling so as to examine the computed results. The study presents a case history along the Greater Cairo Metro tunnel Line 2 to assess the accuracy of the proposed finite element model. Based on this case history, extensive study using the finite element model and the surface displacement equation is conducted to predict the ground movement due to tunneling. 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. For the case study, this paper presents a comparison between the field measurements and those obtained by the finite element analysis and the surface displacement equation. There is a good agreement between computed and measured values. The tunnel system performance is expressed in terms of surface settlement due to the tunnel construction. The study presents the prediction of the surface settlement profile using the proposed model and the surface displacement equation at different sand soil types. The study also examines the results obtained by the surface displacement equation with those obtained by the finite element analysis. The results show that the surface settlement profiles using the surface displacement equation have a good agreement with those obtained by finite element analysis in loose to medium sandy soil. In addition, the surface settlement profiles computed by the surface displacement equation do not agree well with those obtained by the 2-D finite element model in dense to very dense sand soil. However, the surface displacement equation does not include the impact of different geotechnical parameters used to classify the different sandy soil types. | ||
| Keywords | ||
| Tunnels; Settlement; numerical modeling and analysis; nonlinear displacement; surface displacement equation; Deformations | ||
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