Finite element analysis of the twin tunnels-piled structure interaction

The expansion of urban areas has resulted in an increasing demand for underground construction. In most cases, each tunnel line usually builds two parallel tunnels to facilitate efficient traffic management. The ground deformation mechanisms during the excavation of twin tunnels differ from that which occurs during the construction of a single tunnel. The construction of two tunnels in the urban area causes ground displacements and stress redistribution, which pose a mechanical impact on the adjacent pile foundations and underground structures. Therefore, optimization in tunnel design requires predicting the response of pile structures and adjacent underground infrasturcture. The present study delves into the interaction analysis between the twin tunnels and the piled structure through the use of the finite element method. The analysis concentrates on aspects such as surface settlements, the response of tunnel linings and the behavior of piles resulting from the interaction between twin tunnels and deep foundations. The obtained results indicate that the magnitude of the internal forces and displacements of the front pile P1 closer to twin tunnels is higher than for the rear piles P2, P3 and P4. The magnitude of the internal forces and displacements of the piles for the case of twin tunnels T1 and T2 construction are greater than that for the case of single tunnel T1. The second tunnel T2 is located near the multi-storey building, and it is strongly affected by twin tunnels-piled structure interaction and therefore the magnitude of the normal forces and bending moments of the tunnel lining for the case of construction twin tunnels T1, T2 beneath piled-structure are greater than that for case of twin tunnels T1, T2.