Underground tunnels in seismic areas

Analytical and numerical models of the structural safety of an underground tunnel under seismic ac- tions are discussed. Three procedures are compared: the first is analytical, in two versions (Penzien-Wu 1998 and Penzien 2000), and the others are numerical, referring to the computer codes Flush and Flac, in two-dimension space. The analytical procedure considers the soil as homogeneous. The tunnel cross-section is circular and this allows an application to the underground railway of Naples, which has effectively this structural cross-section. When conditions are equal, the three procedures offer similar results in terms of maximum values of internal force components and in fair agreement as distribution along the wall. However important effects are highlighted next to soil discontinuities, in particular in seismic conditions.

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Alberto Castellani, Bruno Cavagna, Michela Chiorboli, Marco Valente