By forming continuous pre-lining around the tunnel's perimeter, pre-cutting is a recognized tunneling technique that enables full-face excavation of a tunnel even in unfavorable ground conditions. In this study, a theoretical method is put out to simulate the performance of this kind of pre-support in squeezing conditions. The loading distribution on the pre-cutting shells is determined for this purpose using the LDP of an unsupported tunnel, and the non-linear stiffness of the pre-cutting shell is then determined using the shell theory. The convergence confinement method is used to calculate how much the pre-supported tunnel is deformed. The non-uniform loading distribution also results in the tangential and longitudinal bending moments on the pre-cutting shell. To show the effectiveness of pre-cutting shells in extreme squeezing conditions, several examples are solved. As a result, a few graphs for the preliminary design of a tunnel using this technique are given. The graphs show the overall tunnel displacement for various pre-cutting shells under various geological conditions. The outcomes demonstrate good agreement between FALC 3D results and the ones by the suggested analytical model. A preliminary design can be made using the assessment of the proposed method on the loads on the pre-cutting system.

Theoretical modeling of the pre-cutting system performance for the tunnel face stability in very weak rock masses / Ajirlou, V. S.; Ranjbarnia, M.; Oreste, P.. - In: TRANSPORTATION GEOTECHNICS. - ISSN 2214-3912. - STAMPA. - 42:(2023). [10.1016/j.trgeo.2023.101073]

Theoretical modeling of the pre-cutting system performance for the tunnel face stability in very weak rock masses

Oreste P.
2023

Abstract

By forming continuous pre-lining around the tunnel's perimeter, pre-cutting is a recognized tunneling technique that enables full-face excavation of a tunnel even in unfavorable ground conditions. In this study, a theoretical method is put out to simulate the performance of this kind of pre-support in squeezing conditions. The loading distribution on the pre-cutting shells is determined for this purpose using the LDP of an unsupported tunnel, and the non-linear stiffness of the pre-cutting shell is then determined using the shell theory. The convergence confinement method is used to calculate how much the pre-supported tunnel is deformed. The non-uniform loading distribution also results in the tangential and longitudinal bending moments on the pre-cutting shell. To show the effectiveness of pre-cutting shells in extreme squeezing conditions, several examples are solved. As a result, a few graphs for the preliminary design of a tunnel using this technique are given. The graphs show the overall tunnel displacement for various pre-cutting shells under various geological conditions. The outcomes demonstrate good agreement between FALC 3D results and the ones by the suggested analytical model. A preliminary design can be made using the assessment of the proposed method on the loads on the pre-cutting system.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11583/2981948