Study on Theoretical Deformation Calculation of Lateral Subway Shield Tunnel Caused by Ultra‐Deep Foundation Pit Excavation

Abstract With the continual comprehensive growth of urban below ground area in China, the need for contortion prediction and control of nearby tunnels caused by dumping of structure pit excavation is becoming a growing number of immediate. Currently, the study on the impact of foundation pit excavation on adjacent structures and frameworks primarily concentrates on mathematical simulation and design measurement, which is not conducive to engineering promo. In view of this, with the academic analysis approach, based upon the Mindlin solution concept, the academic calculation formula of the extra stress of the surrounding passage triggered by the unloading of the structure pit base and the unloading of the pit wall surface is derived. The quantitative connection between the dumping stress and anxiety and the passage deformation during the excavation of the structure pit is established, and the academic estimation formula is validated by a case. The results reveal that the additional tension and deformation of the passage determined by the stress discharging method and the displacement planet stress approach are extremely close, and the stress and anxiety unloading approach is much more straightforward and more suitable for design application. For the foundation pit design with stack (wall surface) ‐bracing maintaining framework system, the value range of side wall anxiety dumping coefficient is between 0.05 and 0.30. It is confirmed by design cases that the theoretical computation formula of tunnel contortion brought on by excavation discharging of structure pit based on Mindlin solution theory is trusted. This formula provides an approximate service for the deformation of surrounding passage triggered by excavation discharging of foundation pit, which is of excellent significance to guide the in‐depth design and building and construction control of the job.