A new method for determining the pore-water pressure around twin shallow circular tunnels

Abstract

In order to obtain the distribution rules of pore-water pressure for twin shallow circular tunnels, the determination approach in the pore-water pressure for the twin shallow circular tunnels buried in a semi-infinite space was proposed by using the bipolar coordinate system method and the Schwarz alternating method for the first time. The solution of pore-water pressure was also obtained by multiple iterations method. The proposed approach was validated by the results of numerical simulation. The maximum error between the results of the analytical solutions from the proposed method and the numerical simulation was only 2.15% when the accuracy was set to 1.0×10-3MPa. At last, influences of the number of holes and the tunnel center spacing on the pore-water pressure were presented. It is shown that the number of holes and the tunnel center spacing were the main factors for the distribution of pore-water pressure, and the pore-water pressure of twin shallow circular tunnels was only greater than the pore-water pressure of single shallow circular tunnel in the upper area of tunnels. And the maximum result for the pore-water pressure of twin shallow circular tunnels was obtained in the midpoint of the tunnel center spacing.