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

342

13

 Without earth filling and with a lead out;  With a partial earth filling.  Upstream earth filling and vertical downstream face; The sections can be with or without the upper railing and can show some lead out. The vertical parameter or the lead out is significant of foundation settlements or unbalanced thrust on the walls. For each section a point placed at the top and three relevant sections are taken. One placed at the half of the wall, the other placed close to the foot of the wall, respectively section 2 is on the masonry and section 3 in on the earth.

(1)

(2)

(3)

(4)

(5)

(6)

Fig. 18. Emblematic sections analysed for the urban walls of Volterra.

5. Discussion and conclusions In this paper, a survey strategy for historical walls is illustrated. The combination of onsite survey and GIS information furnishes complete information to address the vulnerability analysis of these infrastructures. This approach is also suggested in [11][12] about landslide and in [13][14][15] about bridges. From the comparison with other kind of surveys, such as point cloud surveys [16], traditional topographic approach, photogrammetry, the proposed form makes possible a cheaper and effective survey strategy, to identify the most vulnerable sections and to address structural intervention. The intervention has to be addressed not only to aesthetic restoration but in particular to a structural stabilization [17]. For example, in cases 2.2. and 2.3, the aesthetic restoration did not prevent the failures. The recent collapse highlights the need to detect evidences of decay such as signs of moisture, overload and drain presence to be introduced in the vulnerability analysis. In the field of the protection of the existing historical heritage, it is essential to provide a live monitoring system [18]. This in particular for infrastructures as the urban walls in order to guarantee the safety of human life together with cultural heritage protection. Huge economic losses both in terms of private and public assets, especially the interruption of roads, pushed to establish a remote system of displacement control in the case of Volterra. It is check out a system of remote sensing of the South East urban walls (GBInSAR, Ground Based Synthetic Aperture Radar interferometry – TLS, Terrestrial Laser Scanner) [19]. The system can furnish alert to the public authority in case of suspects of an imminent catastrophic event. As a matter of fact, in the case of slopes triggered by atmospheric events it is essential to have clear and fast information and without having access to the risk area. This is crucial especially in areas where the monitoring activity of Volterra is now furnishing the first results. Finally, the evaluation of cost benefits should also be addressed not only to economic costs but also to environmental impacts, by the help of energy considerations [17].