GEOTECHNICAL DESIGN FOR THE STABILIZATION WORKS OF THE LETTOMANOPPELLO LANDSLIDE (ABRUZZO, ITALY)

In order to stabilize the landslide of Lettomanoppello, the stabilization works are finalized to reduce/control the causes and to mitigate the economic, social, and environmental risks. A careful geotechnical design, of the stabilization works can allow an economic recovery of the cost by means of a virtuous and profitable process to produce electric energy. The landslide of Lettomanoppello, located in Central Italy (south-west of the city of Pescara) is a large, very complex active landslide. Slope instability phenomena, often triggered by intense rainfall and seismic events are recurrent in this region of Apennines and frequently result in serious damage to the historical-environmental heritage and in dreadful economic losses. The stability of slope is mainly affects by the hydrogeological conditions of the area characterized by a complex drainage system. Various stabilization works were executed along the slope during the years. The paper presents the studies (geological and geotechnical characterizations) and a general plan of the works required to stabilize the entire slope. The general stabilization project includes different types of works: (i) structural works (retaining walls), effective in short term; (ii) drainage works (tunnel for deep water drainage), effective to medium-long term, aimed at reducing/controlling the major causes of the landslide; (iii) protection from erosion at the toe of slope and surface drainage works. The tunnel crosses a horseshoe shape underneath the historical centre of Lettomanoppello and the elevations of its mouths are at 296 m a.s.l. The drainage waters will be conveyed to pipe towards a hydraulic turbine located at 206 m a.s.l. in the lower part of the slope. Furthermore, the geometry of the cut-off retaining walls at the toe slope are conceived as foundations of aeolian turbines.