3-D strong tilting observed in tall, isolated brick chimneys during the excavation of the Athens Metro

摘要: Excavation of a metro tunnel in the historical centre Athens (Gazi/Technopolis area) soft rocks produced considerable tilting, up to 7.5 ‰, but no damage three isolated brick chimneys, 26–34 m high. Tilting was derived from coordinate changes control points at top chimneys measured remote total station and permitted understand that during excavation, on were moving roughly along semi-circles with radii 20 cm overall motion structures can be simulated by inverted half-cones. While deformation ground due tunnelling so far usually assumed as 2-D effect approximated Gaussian function, evidence presented clearly indicates 3-D (tilting rigid different directions), full agreement new theoretical models nearby excavations (ground loss). Measurement tunnelling-induced became for first time possible two reasons: first, Gazi are slender functioning huge tiltmetres amplifying amount local deformation; most other cases, this is obscured/compensated response bulky buildings. And second, use geodetic stations (electronic theodolites) permits measurement coordinates nearly millimetre accuracy. Observed tilting several times larger than accepted threshold failure tunnelling/excavations, their foundations, limited dimensions directly ground, practically not subject differential displacements. This result important future underground works vicinity such towers, bell towers minarets.