Deep displacements measured with a robotized inclinometer system

In the field of landslide monitoring systems, the Geohazard Monitoring Group (GMG) of IRPICNR have developed and patented a new instrumentation to measure the deep-seated ground deformations using an inclinometer probe within a robotized system. This instrumentation combines the advantages of the traditional measurements (manual readings) with a robotized approach that improves the results in term of revisit time, repeatability and accuracy. The Automated Inclinometer System (AIS) allows to explore automatically all the length of the borehole with just one inclinometer probe. In this robotized system, an innovative Inclinometer Control Unit (InCU) was implemented and directly connected to the probe that allowed to remove all wired connections between probe and Ground Control Station (GrCU). All the cables (probe signal and power supply) were replaced with a fiber cable (Dyneema®, ?2.5mm) just to sustain and movie the probe up/down into the borehole. The InCU device is battery powered and is automatically charged via contactless inductive charging system during the AIS idle time. Measurements are taken during the ascent phase with steps of 0.5m (or 1m). The descent phase (continuous) and the ascent phase (by steps with about 5" break to acquire the inclinometer data) is managed by GrCU through the combined use of a ?motor and a high precision encoder. During measurement into the borehole, the InCU is completely autonomous and analyses the signals received from the probe and stores them into its internal memory. The data analysis system implemented in the InCU, is based on the difference of the inclinometric signal amplitude: in case of probe in motion (between one measuring step and the other) and in case of probe stopped (positioned at the i-th measurement depth). By default, this instrumentation perform automatic double reading (0/180°) for accuracy increasing and errors correction. The system is independent from the length of the borehole (1 to 120 meters for standard model), operates on aluminum or ABS inclinometer casing, is completely remote controlled and is powered by solar panels. The AIS was extensively tested on an inclinometer test tube installed at CNR IRPI in Turin and then in landslide monitoring networks. The analysis of the data (about 500 measurements in the Turin test site and about 600 measurements acquired in El Portalet landslide) allowed to validate the system both in terms of accuracy and repeatability of the measure.