Page 6 - EAI-4_2015_60-68

millimeter (tenths of millimeter Research & development

for the tell-tales). Overall 70

mechanical joint-meters were

installed,distributed along the cliffs

overlooking the sea of the three

bays and also within the numerous

cavities that open inside the cliffs.

The indirect measurements were

carried out through Terrestrial

Laser Scanner and GPS instruments.

While this latter allowed to

monitoring displacements of single

FIGURE 3 3D joint meter installed on the giant joint of the plateaux of the west side of Cala points located at the edge of the cliff,

Rossa (left) and the removable deformeter during the measurement survey the former acquired information

about a cloud constituted by

stereographic projection (lower hemisphere). millions of points representative of the whole vertical face

Furthermore, the mechanical features of the rock of the cliffs highlighted by the laser beam.

mass, including the mineralogical characteristics and Laser scanner survey [17] were performed using a laser

the rock compressive strength, were assessed with scanner (Riegl Z360) integrated with a high resolution

field instruments (Schmidt Hammer sclerometer) and digital camera (Nikon D100; Figure 4). Two Laser

laboratory experiments (thin sections, point load test, Scanner acquisitions (October 2012 an October 2013)

etc.).On the basis of the geological and geomechanical were performed in all the three bays, positioning the

features, the values of Beniawsky/Romana (RMR/SMR) instrument in four stations in Cala Rossa, four in Cala

and Sicily Region classifications [16] were assigned to del Bue Marino and five in Cala Azzurra. In order to

each station.The latter proposes a simplified approach compare subsequent temporal scanning [18, 19] and

generating an aggregate of some geomorphological, re-calibrate the instrument with a precision of mm,

environmental and historical parameters with the eight fix targets and ten mobile targets around the scan

mechanical characteristics typical of the traditional points (scanpositions) were materialized as a Cartesian

classification. coordinates system.

The monitoring activity was performed through the use The GPS monitoring techniques was applied only in

of direct and indirect instruments. Cala Rossa with the aim of identifying the movement

A direct measurements systems was implemented of single points along the cliffs with high accuracy.

with mechanical joints gauges of

different kind (tell-tale, removable

joint-meters, 3D joint-meters;

Figure 3) in relationship with the

different characteristics of the

walls, discontinuities and types of

movement to be recognised (one-

dimensional or three-dimensional).

These three mechanical join-

meters systems allow to measure

relative displacements between

two reference pins or two anchors

positioned across the joints with

a resolution of a hundredth of FIGURE 4 Laser scanner instruments during the acquisition survey in Cala Rossa

63EAI Energia, Ambiente e Innovazione 4/2015