Abstract:The protection of the two existed tunnels is presented , which ase right under Shanghai square excava2 tion and are protected through two methods : ground improvement and considering time - space const ruction proce2 dure. Due to the combining use of the two methods , the normal operation of the two tunnels have been successfully guaranteed. It is analysed in great details how the time and space affect on the rebound deformation of the existed tunnels and how the tunnel deformation is predictde with the thory of residual st ress. At theend , the recorded de2 formations of the two tunnels are given out and the tunnel deformation is divided into three stage. In a word , this excavation made a good example for the future similar engineering.