Analysis of Strata Deformation Patterns Induced by Vertical Shaft Sinking Machine Based on Soil Deformation Zoning: A Case Study of the Zhuyuan Bailonggang Sewage Connecting Pipe Project in Shanghai, China

Field measurements with the Plaxis3D 24.1 software were performed on the 17# shaft of the Shanghai Zhuyuan Bailonggang sewage connecting the pipe project to analyze the ground deformation patterns during VSM (vertical shaft sinking machine) construction in soft soil areas. The results indicate that both the shaft sinking process and construction pauses at the pit bottom significantly exacerbate soil deformation. Compared with horizontal displacement, the measured settlement is more sensitive to excavation depth. The calculations revealed that significant pit bottom heave occurs when the excavation depth reaches 40% to 70% of the maximum excavation depth (Hm). Moreover, the heave pattern transitions from a single-peak “convex” shape to a double-peak “concave” shape during the sinking process. On the basis of the deformation of the soil outside the shaft after the completion of sinking, the vertical deformation zones are classified into a groove-shaped settlement zone, heave influence zone, and heave zone. Similarly, the horizontal deformation zones are categorized as an arch-shaped deformation zone, transition deformation zone, and cantilever bending zone. For regions where the sinking depth reaches 40% to 90% of Hm, the excavation disturbance should be further minimized, and overexcavation must be strictly avoided. In areas where the horizontal distance (L) from the shaft is less than 0.3 times Hm, environmental monitoring points should be appropriately densified to optimize the fine control of deformation in the surrounding region.