GNGTS 2017 - 36° Convegno Nazionale

698 GNGTS 2017 S essione 3.3 Fig. 1 - Acuto quarry test site. Location and ID number of the accelerometers: a) on the block front side (blue circle), on the block lateral side (green circles) and on the rock wall (red circles). b) The vibrodyne (right side) and the K2 datalogger (left side). Dashed limits indicate the position of the accelerometers: on the block (orange), on the rock wall (grey) and on the ground (yellow). Moreover, the three-dimensional mobility of the rock block was investigated in order to define the amount of displacement, the vibrational polarisation in azimuthal direction and the tilt degree induced by each shaking test. At this aim, the accelerometric records were integrated twice to obtain displacement records and processed by a customised software in order to obtain the three-dimensional displacement. The results show a displacement in the order of tenths of micrometer of the rock block and a different polarisation respect to the rock wall for signals recorded when the vibrodyne is turned on, while these values return to the initial condition when the solicitation is switched off. Therefore, this behaviour points out elastic displacements not permanently affecting the rock mass and testifies that the block is cinematically separated by the behind rock wall. Terni test site. On March 2017, a portion of a rock mass in proximity of a tunnel along the Terni-Giuncano railway line was chosen as test site for monitoring the vibrations induced by recurrent transit of trains. The railway line runs along the Serra valley, a narrow valley deeply incised by the homonymous river, in the southern sector of the Martani Mounts, NE of the Terni basin. This area is characterised by folded and fractured rock masses deformed by several thrusts and faults (for instance Monte Torricella thrust and Battiferro fault) related to the Apennine structuration (Calamita and Pierantoni, 1994; Bruni et al. , 1996); in particular, Scaglia Rossa formation crops out in the investigated sector and a geomechanical characterization of the rock mass provided J v :7-10 and I b : 0.3-0.5. Field activities. A seismic monitoring of the rock mass was performed from April 20 to June 15 2017. As shown in ���� �� ��� ��������� ������������ ���� ���� �� ��� � ������� ���� Fig. 2, the monitored sub-vertical rock wall is 4.4 m distant from the railway and its slope face (oriented 260/80 in dip direction/dip convention) is parallel to the railway track, which runs along N-S direction. Four 1-component FBA11 accelerometers were fixed on the rock wall, in particular two at its base (0.5 m from ground) and two at 1.5 m from ground, both couples measuring vibrations along N-S and vertical direction. In addition, two 3-component velocimeters Lennartz ��������� ����� ���� ��������� �� ��� ���� ���� ����� �� LE-3Dlite MkIII were installed at the rock mass base, as