ABSTRACT

The present paper specifically refers to the excavation of the Line 9 between Mas Blau Station and Barcelona airport (Fig. 1). This 4.33 km-long section of the Line crosses an urban area close to some sensitive structures. Ground movements have therefore been a special concern during tunnel design and construction. An extensive instrumentation system has been deployed to control the magnitude and distribution of ground movements and also displacements of the structures during and after the excavation of the line. The article first summarily describes the special geology of the area and its implications for tunnelling. Afterwards, the information derived from this part of the excavation is presented and reviewed. In particular, the following issues are addressed: history of volume loss distribution along the line, magnitude and shape of subsidence troughs, and influence of pressures used during tunnelling on observed movements. Attention is also paid to contributing causes to observed instances of larger ground movements.