Using Grouting of Shield Tunneling to Reduce Settlements of Overlying Tunnels: Case Study in Shenzhen Metro Construction

AbstractGrouting control of shield tunneling is of paramount importance to reduce settlements of existing tunnels below-passed by shield tunneling along a curved alignment and in crowded urban areas. The methodology and scheme of the grouting control of shield tunneling is illustrated taking the first Earth Pressure Balanced (EPB) shield below-crossing existing interval tunnels from Kexueguan station to Dajuyuan station of the Shenzhen metro line No. 1, for example. A combination methodology of the “observational method” and the “predefined design method” was set up to deal with parameters concerning the grouting control of shield tunneling. Some parameters of the grouting control were predefined or suggested before the below-crossing, and other parameters might be adjusted during construction on the basis of the “observational method.” The scheme primarily consists of preparation work before the below-crossing, automatic motoring system used in operation tunnels, simultaneous backfilling grouting and gro...