Displacement Analyses of Main Structure of Parallel Pit Excavation and Analysis of Countermeasures

To solve the impact on pre-existing main structure due to need for early traffic restoration of urban roads within cross-hub and difficulty co-ordinating a construction plan among groups pits, method combining TD BU was proposed. By establishing three-dimensional finite difference (FDM) parallel pit excavation considering small strain constitutive model strata, influence four different schemes structs is studied. The results study show that: (1) asynchronous both sides cover area causes additional deformation steel pipe structs; sequential produces greatest tube columns, followed by staggered least simultaneous excavation; (2) middle 1 slab enhances overall stiffness in area, reducing caused unsynchronized pit, with maximum horizontal 5.8 mm, reduction 61%; (3) greater depth closer distance from more obvious column; (4) function relationship between δhm/H relative coefficient Rd obtained fitting, controlled mis-step spacing foundation 4.3 m when floor cast.