The mechanism of foundation pit excavation affecting the below existing shield tunnel is researched. 14 cases of the foundation pit instance are collected to make a statistical analysis of measured data. The results show that the maximum vertical displacements of shield tunnel are all uplift

and 64% of the tunnel uplift values exceed the alarm value (10 mm). Based on the measured statistical data

an empirical tunnel maximum uplift value prediction formula below pit is proposed. Measured data of displacements in horizontal direction are fewer surveyed; and they are also small; the convergent small deformations change from “horizontal stretching

vertical compression” to the “horizontal compression

vertical stretching”. Based on the at Hangzhou Yan’an Road

underground street passage project

the influence of foundation pit excavation on lower shield tunnel deformation in Hangzhou Metro Line 1 is researched. The measured data of tunnel vertical displacements

horizontal displacements and horizontal convergence deformations are analyzed. The results verify the reliability of theoretical analysis and the proposed formula.