1 Introduction

Rockslides are one of the most hazardous natural events, because of their velocity and rarely detectable precursors. Possible strategies to prevent the risk associated to these events consist in: a) studying the gradual creep-driven deformation of rock mass by setting a proper monitoring system (Loew et al. 2016); b) realizing numerical models also considering progressive failure of rock slopes (Eberhardt et al. 2004); c) coupling microseismic monitoring systems and numerical models, taking in account rock mass damage during time (Xu et al. 2014; Tang et al. 2015); d) analyzing variations of ambient noise as indicators of imminent failure (Got et al. 2010; Lévy et al. 2010).

To investigate long term rock mass deformations due to temperature, wind and rainfalls, the abandoned Acuto quarry rock wall (Frosinone – Central Italy) was selected in Autumn 2015 as test site for the installation of a multi-sensor monitoring system on a rock block prone to failure. The experimental site is included in the carbonatic Monti Ernici ridge. More in particular, Mesozoic wackestone with rudists crops out on the sub-vertical quarry wall with a height ranging from 15 m up to 50 m (Accordi et al. 1986). A geomechanical characterization of the rock mass led to the recognition of four joint sets, here indicated according to dip direction/dip convention: S0 (130/13) corresponding to the limestone strata, S1 (270/74), S2 (355/62) and S3 (190/64) (Fantini et al. 2016). The monitored sector is located in the NW portion of the 500 m long quarry front, which is characterized by the presence of a 64 m3 densely cracked protruding block, separated from the back quarry wall by a main fracture. The multi-sensor monitoring system consists in two weather stations with air-thermometer, hygrometer, pluviometer and anemometer for wind speed and direction, installed at foot and top of the slope wall, one thermometer for the rock mass temperature, six strain-gauges installed on micro-fractures of the rock mass, four extensimeter installed on open fractures and one optical device. Moreover, a railway track was reproduced near the rock mass, to simulate a real rockfall hazard scenario (Fig. 1).

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