# Centrifuge Modelling of the Impact of Excavation with Partition Piles on Adjacent Existing Tunnel
## 1 Introduction  
With the growth of urban populations and the limitations of land resources, the utilization of underground spaces is increasing. Urban underground rail transit, as an effective means to alleviate urban traffic pressure through the utilization of underground space, continues to expand and be constructed worldwide. Alongside this, the excavation work near existing metro tunnels has been a typical occurrence [1; 2; 3; 4; 5; 6; 7; 8]. Excavation can lead to issues such as groundwater level lowering, soil deformation, and vibrations induced by earthquakes, which in turn can result in additional internal forces and deformations in existing tunnels, posing potential impacts on tunnel safety. Therefore, research on the effects of excavation on nearby tunnels has gained significant importance and urgency. In recent years, numerous scholars have undertaken a series of studies on this matter [9; 10; 11; 12; 13; 14; 15; 16; 17; 18; 19; 20; 21]. [PERSON] [9] examined how deep excavation affects an underground tunnel network in a specific office building using a 2D finite element model. The model calculations showed a maximum heave of 22 mm in the basement. The maximum tunnel heave and diameter change in the existing tunnel network reached 14 mm and 4.5 mm, and the finite element calculation results matched well with the measured results. [PERSON] et al. [10], on the other hand, conducted three-dimensional centrifuge modelling, and it was found that the excavation has an approximate influence range of 1.2 times the length of the tunnelon its longitudinal vertical displacement. The maximum upward movement of the under tunnel and the greatest settlement of the neighboring tunnel were approximately 0.07% and 0.014% of the excavation depth, respectively. [PERSON] et al. [11] conducted a battery of centrifuge modelling experiments and determined that the influence range of tunnel heave extended to approximately 2.5 times the excavation width from the excavation boundary. [PERSON] et al. [12] conducted centrifuge modelling and found that the total settlement of the tunnel reached 1.6 times the settlement during excavation after 815 days of completion of excavation. [PERSON] et al. [13] employed field monitoring and numerical simulation analysis to investigate the effects of a substantial excavation on adjacent subway tunnels. The results showed that tunnels with high-stiffness linings might have smaller deformations but might have to withstand larger moments. Simultaneously, ensuring the long-term and sustainable operation of existing subway tunnels became a significant concern in urban underground engineering construction. There were various measures to control the deformation of existing subway tunnels caused by underground construction, such as phased excavation, soil grouting reinforcement, and pile reinforcement [22; 23; 24; 25; 26; 27; 28; 29]. A noticeable gap often existed between the existing tunnels and the excavation retaining structures. In engineering practice, partition piles or walls were frequently installed in this area to impede the transmission of deformation from the excavation to the surrounding soil, thereby minimizing the deformation of the existing tunnels. However, in recent years, research on partition piles has yielded varying conclusions regarding their effectiveness in controlling tunnel deformation [30; 31; 32; 33; 34; 35; 36; 37; 38; 39; 40]. [PERSON] et al. [32] found that the presence of a partition wall can significantly reduce the maximum surface settlement outside the excavation and horizontal displacement of the retaining wall, leading to a noticeable reduction in damage to surrounding structures caused by excavation. Nonetheless, the partition wall's impact on the displacement field of deep soil demonstrated substantial variation with depth. [PERSON] et al. [35] employed numerical analysis to investigate the influence of partition piles on the displacement field of the soil surrounding the excavation.