PSI - Issue 28

M.L. Puppio et al. / Procedia Structural Integrity 28 (2020) 330–343 Puppio M.L. et al/ Structural Integrity Procedia 00 (2020) 000–000

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of the thrust on the upstream line of the wall, (ii) the reduction of the shear resistance of the wall and the soil behind, together with the boundary conditions [6]. The structural condition depends on the type of masonry [8], the presence of frictional joints [7] and the internal core. A screening of the most relevant sections with the GIS is proposed, integrating with in situ survey (laser distance meter, meterstick, level) (Fig. 9). The GIS application is based on the layering of the shapefile with images from Google Earth [9]. It is not recurring to find a map with a digital representation of the walls. In the case study of Volterra it is possible to find a meticulous representation of the details of the access arch in [10]. There is no digital representation available of the entire architectural complex so, in order to provide a survey campaign, 107 vertical sections are identified (Fig. 10-Fig. 11) with the following criteria. Identification of:  A vertex for each angular discontinuity;  Further checkpoints with a relative distance not exceeding 50 meters;  Additional checkpoints in areas that are evaluated as relevant during the survey.

Fig. 9. Integrated GIS and on site data.

Fig. 10 shows the path of the walls: each section is labelled with a progressive number. With the help of GIS, it is possible to associate to each label the following information:  absolute distance from the initial points;  relative distance;  topography coordinates;  altimetry. For contiguous sections with similar features, the data are extrapolated from the nearest. From a visual analysis of the aerial pictures (Fig. 11) and a survey made along the walls, it can be observed that part of the walls are incorporated into buildings or are interrupted by gates, this complicates the automatic survey. In situ survey aims at obtaining the most relevant geometric information. The declivity of the upstream and of the downstream wall face is measured with the help of a level, together with the slope of the terrain. This info can be also deduced from the plugin Profile tools in GIS context, through the upload of the raster DEM (Digital Elevation Model) of the District of Pisa or, in absence, with LIDAR maps.