Abstract：In the construction of subway，tunnels crossing the adjacent pile group of the existing high-rise buildings may cause excessive settlement and tilting of the piles. In this study，a series of three-dimensional centrifuge model tests and numerical simulations using an advanced hypoplastic soil model were carried out to investigate the response of an existing pile group to side-by-side twin tunneling at two typical depth，namely near the pile toe(Test TT) and below the pile toe(Test BB). Firstly，the sand layer with pile group foundation was prepared by rain flow deposition method. Secondly，under the condition of 40 g，the effect of staged excavation was simulated by drainage of water bags. Meanwhile，the settlement and rotation of the pile group was measured by linear variable differential transformers. Finally，through the finite element analysis，the settlement and lateral inclination of pile foundation are computed and compared with the centrifuge test results. The results show that：In the two tests，the maximum settlement of pile foundation is 2.1% and 2.4% of pile diameter respectively，and the
maximum inclination occurs after the first tunnel excavation，which is 0.2% and 0.08%，respectively. When the depth of tunnels is large，the settlement of pile foundation is large but the rotation angle is small，the pile group changes to the friction pile，and the strength utilization of the soil unit at the base of pile decreases. When the depth is small，the settlement is small but the rotation angle is large，the pile group changes to the end bearing pile，and the strength utilization of the soil unit increases.
2021, Vol. 40 
