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.