Comparison of Approaches for Data Analysis of Multi-Parametric Monitoring Systems: Insights from the Acuto Test-Site (Central Italy)

Abstract

This paper deals with monitoring systems to manage the risk due to fast slope failures that involve rock masses, in which important elements (such as infrastructures or cultural heritages, among the others) are exposed. Three different approaches for data analysis were here compared to evaluate their suitability for detecting mutual relations among destabilising factors, acting on different time windows, and induced strain effects on rock masses: (i) an observation-based approach (OBA), (ii) a statistics-based approach (SBA) and (iii) a semi-empirical approach (SEA). For these purposes, a test-site has been realised in an abandoned quarry in Central Italy by installing a multi-parametric monitoring sensor network on a rock wall able to record strain effects induced by natural and anthropic forcing actions (like as temperature, rainfall, wind and anthropic vibrations). The comparison points out that the considered approaches allow one to identify forcing actions, responsible for the strain effects on the rock mass over several time windows, regarding a specific size (i.e., rock block dimensional scale). The OBA was more suitable for computing the relations over short- to medium time windows, as well as the role of impulsive actions (i.e., hourly to seasonal and/or instantaneous). The SBA was suitable for computing the relations over medium- to long time windows (i.e., daily to seasonal), also returning the time lag between forcing actions and induced strains using the cross-correlation statistical function. Last, the SEA was highly suitable for detecting irreversible strain effects over long- to very long-time windows (i.e., plurennial).

Rock Surface Strain In Situ Monitoring Affected by Temperature Changes at the Požáry Field Lab (Czechia)

“…Some examples of test sites around the world are described in the literature, analyzing data using numerous approaches and defining various types of destabilizing phenomena [ 33 , 38 , 39 ]. The novelty of our study area lies in the different latitude of the location, in which, from a climatic perspective, it is possible to observe a different range of temperatures, compared with the other test sites worldwide.…”

“…The instruments can be used for both long- and short-term applications [ 23 , 33 ], but a meaningful change in the long-term resistivity of the wires may be caused by thermo-cyclic loading (long term drifting), and it can cause inexplicable changes in the rock strain trends [ 66 , 67 ].…”

“…On this basis, the objective of the work remains significant, and the applicability of resistivity strain gauging for rock strain dynamics is discussed in detail. Few applications of resistivity strain gauging (in field conditions) are presented in the literature [ 23 , 33 ], and these few do not account for the thermal sensitivity of the sensors. Additional complexity arises from the different configurations of resistivity grids that may influence the results.…”

Environmental forcings and micro-seismic monitoring in a rock wall prone to fall during the 2018 Buran winter storm

“…The quarry is located in the Acuto municipality 100 km SE of Rome and is characterised by a 500 m long and sub-vertical quarry front made up of Cretaceous limestone that reaches a height up to 50 m and was intensively pitted until the late 70 s. The monitored area is located in the NW sector of the quarry, where a 20 m 3 rock block jutting out from the quarry wall is separated from the quarry wall itself by a decimetric-wide sub-vertical joint. The rock block has been instrumented with: (1) one thermometer for measuring the rock mass temperature installed at a depth of 8 cm from the free surface exposed eastward (sensitivity: 0.1 °C); (2) six strain gages (sensitivity: 1 μstrain) installed over the rock block on micro-joints; and (3) four extensometers (sensitivity: 0.01 mm) installed on the steeply dipping open joints that separate the rock block from the wall behind it (Fiorucci et al 2020). Additionally, the monitoring system is completed by a fully equipped weather station placed at the top of the quarry wall that is composed of an air thermometer (measurement range −40 °C/ + 60 °C), a hygrometer, a rain gage (sensitivity: 0.2 mm H 2 O, WMO standard) and an anemometer for determination of wind speed and wind direction (Fantini et al 2017b).…”

Rock Slope Stability under Temperature Fluctuations

“…These are just a few works from a wide variety of projects for monitoring rock movements along slopes. One of the difficulties is isolating the temperature's effect from the other factors that can lead to slope failure, as discussed by Fiorucci et al [7]. Moreover, asymmetry in the block system leads to the development of preferred directional stresses that can induce permanent displacement of rock blocks.…”