Centrifuge Modelling of the Impact of Excavation with Partition Piles on Adjacent Existing Tunnel

Recently, due to more excavation projects near existing tunnels, the research on tunnel deformation control has become very important and urgent. However, the systematic study of the control effectiveness of partition piles, one of the commonly used methods for controlling tunnel deformation, was not mature yet. In response to this situation, a series of centrifuge modelling studies were performed to explore how nearby existing tunnels respond to excavations with partition piles in a dry sand foundation. The tests provided insights into the variations of the horizontal displacement of retaining walls, surface settlement, the horizontal and vertical displacements of the tunnel, and the circular induced strain of the tunnel. The test results showed that the horizontal displacement of retaining walls exhibited a cantilever-type displacement pattern. The most significant surface settlement occurred near the retaining wall and decreased as the distance from the retaining wall increased. The overall deformation of the tunnel roughly showed an ellipsoidal deformation pattern in the horizontal direction. The maximum horizontal displacement was observed at the right shoulder of the tunnel, while the maximum vertical displacement occurred at the right arch of the tunnel. Increasing the length of the partition piles led to a deterioration in their deformation control effectiveness. The top burial depth of the pile could further improve the control effectiveness of the partition piles. However, when the top burial depth of the pile was excessive and exceeded its critical value, the improvement effect of the burial depth on the partition piles diminished.