2D Numerical Analysis of Shallow Closely-spaced Twin Tunnels in Loose Deposits

The mechanical behavior of shallow closely-spaced twin tunnels in loose deposits during construction is analyzed with the finite element method.The numerical results show that the ground settlement occurs mainly between the crowns of twin tunnels.The disturbed zone of of the crown of the later tunnel is greater than the preceding tunnel.The construction sequence has great effect on the displacement path of the crown but barely on the total deformation.The lock foot anchor on tunnel frame plays an important role on the controlling of tunnelling.