Study on calculating methods of soil vertical deformation induced by pipe jacking construction

Based on the previous study, general empirical formula to calculate settlement at any point is advanced by combining three existing empirical formulae. Assuming soil is not drained, the computing formulas of soil vertical deformation 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. Combining the formula of ground deformation induced by ground loss, the formula of total soil vertical deformation induced by pipe jacking construction is obtained. This method can be applied to the construction phase. As is shown in analytical calculation, bulkhead additive thrust will make the frontal soil of excavation face heave and the rear soil subside. Surface deformation induced by bulkhead additive thrust is small during normal construction; and the curves are anti-symmetry with axes of excavation face. For the surface deformation induced by force of friction between shield and soil and induced by force of friction between follow-up pipes and soil, both of their curve distributions are similar to that of bulkhead additive thrust with the axes at the middle of shield and at the middle of follow-up pipes respectively.