Displacement control in irregular deep excavation adjacent to tunnel groups in structural soil: A case study of MJS']JS cement-soil composite piles and grouting rectification

With the gradual development of urban construction, more high-rise buildings with deep foundations are been constructed near tunnel groups. Analyzing how tunnels and surrounding strata respond to diverse construction strategies and challenging conditions during the excavation is crucial. This examination is instrumental in safeguarding infrastructure and minimizing construction expense. This paper explores the deformation response of structures and ground caused by irregular deep foundation pits that are excavated in structural strata adjacent to a tunnel groups (<5 m), as well as the effect of displacement control through grouting rectification techniques and Metro Jet System (MJS) isolation piles. Firstly, a finite element (FE) model is established to investigate the effects of MJS geometric and mechanical properties on deformation response for tunnels and surroundings. Then, an evaluation of the disturbance of underlying structural strata of the site is carried out to analyze the impact on deformation response. Finally, the displacement control effect of rectification technology is analyzed through a case of adjacent excavation. The results indicate that: (1) Strengthening the geometric and physical properties of MJS piles within a certain range positively contributes to deformation reduction. Additionally, increasing the length of MJS piles preferentially with the same amount of mud improves displacement control more effectively; (2) Increased soil disturbance weakens its structural integrity, amplifying the impact of excavation on structures and surroundings; (3) Employing rectification techniques proves effective in preventing excessive tunnel deformation. This study offers valuable insights for design and construction of deep excavation projects adjacent to tunnel groups.