Determination of Face Pressure in EPB Tunneling Machines

Tunnel Boring Machines are the most commonly used machines in the excavation of urban tunnels. Damage to the structures on the tunnel route during or after the tunnel excavation is one of the most important risks. In urban tunnel excavations, which are generally excavated in weak and difficult ground conditions, machines working with the Earth Pressure Balance Method are used. These machines, prevent the inward movement of the tunnel face and control the amount of settlement by applying pressure to the tunnel face. The most important question here is to determine the amount of pressure to be applied to the tunnel face. There are many widely accepted formulas used in the calculation of the face pressure and these formulas generally try to limit the settlements on the ground by using parameters. In this study, a new formula was developed. This new formula calculates the face pressure required to be applied by EPB to the tunnel face in order to prevent damage to a structure located on the route and within the area to be affected by tunnel excavation, instead of only preventing settlements on the surface.