ABSTRACT
Constructing a 105m length traffic tunnel with a depth of 3m underneath a two-way railway and a two-way metro line is discussed in this paper. With due attention to fine grained soil terms ‘ML’ in tunnel excavation environment and low overburden, settlement and face stability control of excavation in return of dynamic rail loads were this project main challenges. For excavation stabilization, some integration methods for pre-consolidation according to sensitiveness and project restrictions were used, which are: Excavation of five parallel micro tunnels in the top of the tunnel section and convert them to reinforced concrete longitudinal beams, and implementation of umbrella grouting system on top of the tunnel section. Finally, this project was inaugurated with a maximum ground surface vertical deformation of 31mm without any disturbance on the trend of railway and metro utilization. Results of numerical modeling and analysis were compared and discussed with monitoring results.
