عنوان مقاله [English]
نویسندگان [English]چکیده [English]
One of the most important problems during the tunnel construction in weak grounds with difficult condition is to provide efficient support and prevent from failures and deformations in tunnel crown and face. In order to regulate the rigidity of the advance core and thereby to create the appropriate conditions for complete control of the deformation response of the grounds having poor mechanical strengths, and therefore, in the final analysis, for complete stabilization of the tunnel in the long and short term, the use of pre-confinement methods is unavoidable. In this study, the application of some pre-confinement methods for stabilizing the Alborz tunnel passing the Kandovan fault has been investigated by means of numerical modeling. It has been concluded that a combination of mechanical precutting and fiber glass face bolts could effectively improve the stability of the tunnel along the weak fault.
Ground improvement techniques to overcome difficulties of tunnel excavation in the past decade have considerably been developed and the use of these techniques is consistent with development in technology. Advances in electronics and mechanical engineering have led to the ability of excavating a tunnel under complicated geological structure and to have confidence in a safe and affordable condition. In order to create the right conditions for complete control of the deformation response of the grounds having poor mechanical strengths, and therefore, for complete stabilization of the tunnel in the long and short term, the use of pre-confinement methods is unavoidable.
Methodology and Approaches
The finite difference based numerical modeling tool FLAC3D was used in this study to model the process of support in Alborz tunnel passing through Kandovan fault. Mechanical precutting as one of the effective pre-confinement methods is used in this study. Furthermore, the effect of fiber glass bolts on the tunnel stability has been investigated independently and also in combination with mechanical precutting method.
Results and Conclusions
Based on the results of this study, the mechanical precutting in combination with fiber glass face bolts can successfully reduce the plastic zones around the tunnel and its face, resulting is a more stable ground for tunneling. Therefore, the combination of precutting and fiber glass face bolts is recommended for pre-confinement of Alborz tunnel passing through Kandovan fault.