Prediction of settlement induced by ground loss during pipe jacking construction

Ground loss is inevitably produced during pipe jacking construction; and ground settlement is brought consequently. Based on the previous study, general empirical formula to calculate settlement at any point is advanced. Assuming soil is not drained, the Sagaseta formula is modified by considering the Poisson's ratio of soil and adopting oval-shaped ground deformation pattern around tunnel section. It is shown in analytical calculation that, for the spot far from the rear of excavation face, the calculation results using the modified Sagaseta formula is quite accordant with that of the Peck formula and the Loganathan formula. The calculated deformation rule using the modified Sagaseta formula is accordant with that of the accumulated probability curves. Both ground settlement above the excavation face are half of the maximal ground settlement; but the accumulated probability curves own smaller effecting range and quicker convergence speed. These calculation methods also apply to shield construction.