Influence of Shield Tunneling Construction on Formation and Existing Tunnel Deformation

In recent years, the construction of urban subways in China has grown rapidly, which has led to the emergence of undercutting projects under existing tunnels. This paper takes the tunnel of the existing subway line 1 under the shield tunnel of Sanshanjie Station to Chaotiangong Station of Nanjing Metro Line 5 as the engineering background. Dynamic simulation of the double-line shield tunneling process was carried out using the finite element software Midas-GTS NX. It is revealed that the deformation of the stratum and existing tunnels is affected by the construction of shield tunnels. The results show that when the shield tunnel is under the existing tunnel, the stratum and the existing tunnel will produce large uneven settlement. At the same time, a large horizontal displacement is generated for the existing tunnel, thereby causing torsional deformation of the tunnel. This phenomenon will seriously affect the safety of tunnel operations. Therefore, this paper proposes to strengthen the stratum of the intersecting area of the two tunnels.