Design of steel fiber reinforced segmental lining for Line 5, Lot 7 of Metro Sao Paulo
The alignment of Metro Line 5 Lot 7 runs for 5.75 km under the city of Sao Paulo with an overburden between 7 m and 47 m. The tunnel is excavated with an EPB-shield of 10.58 m diameter mainly in sands and clays, with a short part where an organic clay layer is encountered within the cross-section. For the horizontal stresses in the ground a coefficient of lateral stress between 0.5 and 0.8 is expected where the overburden is low, and up to 2.0 where the overburden is high. The segmental design is optimized to allow for steel fiber reinforcement wherever possible. Verifications are performed with beam- and finite-element-models utilizing nonlinear material behavior for the concrete. The applied tensile behavior of the steel fiber reinforced concrete is backanalyzed from test results. Cross-sections represent the characteristics of the alignment with low and high overburden and existing structures, which in some places are in extreme proximity to the tunnel.