This paper presents the Marques station from Metro do Porto. The station is built in a central elliptical 27m deep shaft, 48 and 40 m wide along its axis, from where two opposite galleries 18 m long and with about 18m wide form a section of 180 m2. The construction of the station was performed in a heterogeneous granite formation intercepted by a sub-vertical probable fault, slightly oblique to the longer axis on the shaft, Numerical 3D and 2D models were developed, using the formulation of a KES system in order to determine the geomechanical parameters of the granite formations. The established monitoring plan is also presented and some numerical and monitored results are compared giving with good agreements.
This paper presents the Marques Station from Metro do Porto. Particular emphasis is given to complementary numerical modulation in relation to the design. The numerical analysis was done based on software FLAC3D from Itasca and Phase2 from Rocscience, and on the study of structural behaviour of Marques underground station, The geomechanical parameters considered in the modulation were obtained through information of other authors and knowledge rules developed by a KBS system (Knowledge Based System), designated GEOPAT, and prepared in the scope of a reported MSc Thesis (Miranda, 2003).
The Station belongs to the S line of Metro do Porto network, which connects the University area of Asprela and S. Joāo Hospital to Vila Nova de Gaia, being about 8.6 km long. This line includes 7 underground stations and a 3.9 km tunnel, performed with Herrenknecht EPB (Earth Pressure Balanced) TBM (Franco et al., 2004; Santos et al., 2004).
The work consisted of the excavation of a main elliptical shaft and two galleries, opposed in a diametrical way, and it is located in a high historical and social valuable area, the old garden of Praça Marquês de Pombal (Fig. I).
This solution made it possible to excavate the lateral galleries, making the totality of the boarding platforms and accesses, elevators, ventilation and logistic
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structures being made within the shaft's body (Fig. 2). The shaft was constructed in order to minimize the occupied space and social impact, either on car traffic or on existing arboreal species. The design was an alternative from the initially proposed in cut and cover method, being executed with diaphragm walls and concrete piles, strutted and anchored.
The shaft presents an elliptical shape with a longer diameter of 48 m and a minor one of 40 m, achieving a depth of 27 m, with an area of 1400 m2 in horizontal projection and an excavation volume of approximately 37,800 m3 (Fig. 2). The ellipsis' main axis is aligned with the longer dimension of the square.
The two galleries located in the East and West sides of the station are 18 m long and have a 180 m2 section (Fig. 3). The galleries cross section presents approximately a 13 m height and 18 m width.