Classification and selection methodology for temporary support systems for underground structures

Abstract

In this paper a new methodology for evaluation and classification of support system that can be applied to rock tunneling is discussed. It is of great importance to consider long-term stability of rock mass around the openings of underground structure, during design, construction and operation. Varying geological conditions can lead to complications with respect to any underground excavations. The support system may be designed based on empirical, analytical and numerical methods. The support should be installed immediately after the excavation, delayed causes deformation. In this context, many temporary support techniques are chosen to perform as pre-support that can be installed during the first face of excavation around of underground openings. Temporary support used before the excavation for poor rock mass quality to increase the stand-up time by making generally an arch. These supports can also be installed during the excavation and in this paper Arch Method is discussed. Three types of techniques are used in arch method viz. forepoles, grouted arch & spiles. This method is highly recommended and proven system that can be installed within tunnel excavation.