Abstract
Designing a suitable, applicable and efficient support system for underground road structures have always been one of the most important engineering tasks for tunnel engineers. There are some different support systems applied to making underground structures safe against overburden and lateral pressures. Among these systems, permanent or temporary steel frames, wire meshes, rock bolts and shotcretes have been commonly used for suffering the exerted burdens and making the structure a safe place. This paper proposes a numerical analysis of the geometrical instability of steel-arch shells as one of the main bodies of underground road structure liners by means of calculating their buckling load and utilizing the finite element method. In this regard, a considerable number of structures (84) having different geometrical parameters have been modelled and their buckling loads have been calculated. For this purpose, the thickness, internal angle and radius of the periphery cylinder of the arch-shell system were considered taking into account geometrical parameters. Moreover, to accurately model the buckling load using the proposed algorithm, the weight of the structure has also been included in the made calculations. Finally, as the main scope is based on the Cosine Amplitude Method, sensitivity analysis is carried out to investigate the strength of the relationship between each input geometrical parameter and their buckling load. Based on the obtained relationships, the thickness of the structure is reported as the most affective geometrical parameter on buckling steel arch-shell support systems. In addition, the internal angle of arch supports is the least influential parameter.
Highlights
To counteract the threats imposed as a consequence of road structure falls, understanding the most important cause of their instability and designing a powerful support system will be significantly helpful
There are a number of support systems that can be applied to resisting against the instability of underground openings such as rock bolting, wire meshes, shotcrete, steel frames, liners, etc
As a matter of fact, arch-shell steel liners are broadly used for supporting underground road and mining tunnels
Summary
To counteract the threats imposed as a consequence of road structure falls, understanding the most important cause of their instability and designing a powerful support system will be significantly helpful. This issue was critically perused and investigated taking into account different standpoints In this regard, all concerning parameters such as boundary conditions, pre-buckling deformations, geometric imperfections, and load eccentricities were studied (Almroth 1966; Hoff 1966). All concerning parameters such as boundary conditions, pre-buckling deformations, geometric imperfections, and load eccentricities were studied (Almroth 1966; Hoff 1966) Despite of this bulk of studies, due to sensitivity to small geometric imperfections in arch-shell liners and complicated nonlinear partial differential equations governing them, solving a meaningful number of arch-shell buckling problems is theoretically difficult. Using sensitivity analysis, the parameter highly influential in the buckling load has been investigated
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