# Centrifuge Modelling of the Impact of Excavation with Partition Piles on Adjacent Existing Tunnel
## 1 Introduction
The numerical analysis results indicated that partition piles had opposite effects on soil displacement in different regions, as depicted in Figure 1. Thus, the effectiveness of partition piles in controlling the displacement of deep tunnels remained a subject of debate. [PERSON] et al. [37] conducted three-dimensional centrifuge modelling with protective partition walls and found that the installation of the partition wall, to some extent, reduced tunnel heave, but the effect was not very significant. [PERSON] et al. [38] utilized the numerical simulation method to conduct an extensive parameter study, investigating the action mechanism of partition piles in a substantial and deep excavation project near an existing tunnel in Tianjin. The study findings revealed that under substantial traction effects, partition piles might even significantly increase the horizontal displacement of the soil within a specific depth range, consequently impacting the tunnel within that range. Based on the above-mentioned literature, it was evident that within a certain depth range below the surface, the horizontal displacement of the soil increased when there were partition piles. The presence of partition piles induced displacement in the surrounding soil within this range towards the excavation, and this effect was also known as the traction effect of partition piles. If the existing tunnel happened to be within this range, the horizontal displacement of the tunnel might increase due to the traction effect of the partition piles, which was detrimental to controlling tunnel deformation. Therefore, selecting reasonable design parameters for partition piles was crucial. Increasing their protective effect while reducing the traction effect had a positive significance in achieving optimal deformation control for existing tunnels outside the excavation. The above studies indicated that the mechanism of partition piles in controlling tunnel deformation was not yet clear, and there was a lack of systematic research on their control effects on soil and tunnels. Furthermore, there were relatively few centrifuge models specifically dedicated to investigating the effects of excavation on nearby existing tunnels and even fewer centrifuge models dedicated to studying the protective effects of partition piles. Therefore, it was necessary to further conduct relevant centrifuge modelling. In this paper, through two-dimensional centrifuge modelling, the study examined the impact of excavation on adjacent tunnels and investigated the controlling effects of partition piles on tunnel deformation in a dry sand foundation. The study obtained the deformation characteristics of tunnels under the influence of excavation and analyzed the patterns of surface settlement, horizontal displacement of retaining walls, and the circular induced strain of the tunnel. By varying the pile length and top burial depth of the pile as variables, the test revealed the patterns of control effects as these parameters changed and unveiled the mechanism of partitioning piles to control tunnel deformation.