The computing formulas of superimposed load on adjacent level parallel pipe induced both by bulkhead additive thrust

force of friction between shield and soil

and force of friction between follow-up pipes and soil are derived from the Mindlin solution in elastic mechanics. The influences of pipe net spacing distance

pipe diameter

buried depth and soil’s Poisson ratio on the distribution of superimposed load are discussed. The analytical results show that the pressure on adjacent level parallel pipe induced by force of friction between follow-up pipes and soil is small during injecting slurry; and the peak value appears at the back of excavation face. When construction is in normal

superimposed load induced by bulkhead additive thrust is very small. For adjacent level parallel pipes

pressure is produced in front of excavation face while pull force at the back. They distributed antisymmetrically with the axes of excavation face. Superimposed load induced by force of friction between shield and soil and is much larger than that of bulkhead additive thrust with its “zero point” at the middle of shield. The force of friction between shield and soil plays a leading role

thus

it should be considered highly during construction.