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DIFFERENT VIEW OF NUMERICAL MODELS IN NATM AND ADECO - RS TECHNOLOGIES

Jana Chabroňová

Abstract

In Slovakia, there are two technologies NRTM and ADECO ? RS which are currently used for a tunnel excavation. During the tunnel excavation, a disruption of primary balance tension state occurs in a tunnel face followed by spatial redistribution stress, which results in creating a new equilibrium state of tension in the around rock mass. Changes in tension are connected with deformation of the excavation face, or the primary lining and round rock mass respectively. Practical experience and results of spatial numerical models reveal that some of the rock mass deformations occur before the face, another part before the setting of primary lining. In case, this part of the deformation is not controlled by technological measures, it might take its own course. The NATM method is based on deformation checks of relatively soft and flexible primary tunnel lining. The NATM method restrains unfavourable deformations by creating of an optimal bond of tunnel rock during anchor system saddling, an excavation face dividing, and other elements to support a primary lining. The ADECO ? RS method is used for restraining a tunnel face and followed by construction of solid primary tunnel lining. This method is based on the assumption that there is a direct connection between the face tunnel deformation of the excavation and the size of the deformations activating before or respectively, behind the face. Unwonted deformations are eliminated in advance by measures taken before the face of the tunnel excavation. The basic support elements are solid primary lining reinforced by steel girder, reinforcement of tunnel face front (core) by fiberglass anchors, full section face excavation, concreting of secondary lining with minimal distance by tunnel face. Both technologies are more or less responsive to actual geotechnical conditions and the method of support of tunnel excavation can be modified operatively. The aim of the article is to compare the use of the different support elements and methods in the numerical models.

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DOI resolver: doi.org/10.5593/sgem2018/1.2/s02.027

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