Using several monitoring techniques to measure the rock mass deformation in the Montserrat Massif

Abstract

Montserrat Mountain is located near Barcelona in Catalonia, at the north-east cornerof Spain, and its massif is formed by conglomerate interleaved by siltstone/sandstone withsteep slopes very prone to rock falls. The increasing visitor’s number in the monastery area,reaching 2.4 million per year, has pointed out the risk derived from rock falls for this buildingarea and also for the terrestrial accesses, both roads and rack railway. A risk mitigation plan iscurrently been applied for 2014-2016 that contains monitoring testing and implementation as akey point. The preliminary results of the pilot tests carried out during 2014 are presented, alsoprofiting from previous sparse experiences and data, and combining 4 monitoring techniquesunder different conditions of continuity in space and time domains, which are: displacementmonitoring with Ground-based Synthetic Aperture Radar and characterization at slope scale,with an extremely non uniform atmospheric phase screen because of the stepped topographyand atmosphere stratification; Terrestrial Laser Scanner surveys quantifying frequency forunnoticed activity of small rock falls, and monitoring rock block displacements over 1cm;monitoring of rock joints with a wireless net of sensors; and tentative surveying for singularrocky needles with Total Station.