DEVICE FOR APPLYING PRELOAD TO FLEXIBLE BOARD UNDER FOOT OF ARCH USED FOR TUNNEL EXCAVATION

摘要

PURPOSE: To block sinking of an arch used for excavation of a tunnel and sinking of a protection top rail consisting of micropiles most of which are placed on the arch. CONSTITUTION: A device is designed to apply a preload for a floor 6 apt to bend below legs 3 of an arch in order to block sinking of an arch on which a load is exerted due to the weight of earth situated above a tunnel, which occurs as a result of a protection coping being apt to bend subsequently to excavation of earth below the protection coping supported by an arch. A base consisting of two surfaces to form the flanks is arranged at legs 3 of the arch of a room 8, the surface coupled to the leg has rigidity and a surface 9 placed on a ground has bendability and stretchability. The room 8 is pressurized by fluid and deformed on a ground apt to bend and this constitution blocks sinking of the arch.