A Distributed Wireless Soil Displacement Measurement System for Active Monitoring of the Excavation Front of a Gallery

In this paper, an innovative instrument for the measurement of the soil displacement, developed at the laboratories of the Departments of Civil and Information Engineering of the University of Parma and currently under patenting, is presented. The instrument, which can be used in any application requiring soil movement measurements, has been originally designed for the measurement of the axial terrain displacement during gallery excavation. The methods currently in use for this type of measurements, together with their advantages and disadvantages, are illustrated, motivating the reasons which have brought to the proposed innovative measurement system. The instrument allows to measure the soil displacement along an axis perpendicular to the excavation front, during a gallery excavation, through continuous measures based on the use of potentiometers. The transmission system is wireless, with multi-hop communications. This eliminates the limitations imposed by the cables which make the reading and data collection operations difficult. In particular, the wireless technology utilized during the project is based on the Z-Wave protocol, originally developed for home applications. This wireless four-layer communication protocol is based on the creation of a network with a single controller and several slaves. The system has first been set and tested in the laboratories and, then, outdoor (under gravel and clay). The obtained results are very satisfactory.