Journal of Korean Tunnelling and Underground Space Association ISSN:2233-8292(Print) 2287-4747(Online) 한국터널지하공간학회 논문집

The vertical shaft and connection tunnel widening section that is the subject of this study has a large cross-section of 32 m in width and is a three-dimensional connection structure with connection passages connected on three sides, so it is difficult to expect stress distribution effects due to closure, and design such as numerical analysis in fracture zones and connections due to large-depth excavation As stress greater than expected may occur, it is necessary to establish additional reinforcement measures for the partial fracture zone and the expected concentrated stress section at the connection. In particular, as a method of connecting the intermediate slab and the lining, the fixed connection generates a slightly greater axial force than the hinge connection, but due to the nature of the slab structure, it exhibits bending behavior with sufficient margin for axial force, so the fixed connection method was analyzed as appropriate due to its ease of constructability and detailed reinforcing structure at the connection.