Quarry-Induced Slope Instability at a Broadcasting Transmission Plant near Valcava, Lombardia, Italy

Since 2006, a broadcasting tower and ancillary buildings on the top of a hill adjacent to a large, active limestone quarry, in northern Italy near the village of Valcava, has been heavily damaged by ground deformation due to slope instability. In 2005, the quarry began to work the slope toward the broadcasting plant, releasing bedding planes that affected the tower site: a number of fractures occurred in the warehouse and in the ground around it, that grew particularly during significant rainfalls. In October 2006 a landslide occurred in the quarry area, close to the broadcasting site. In order to understand what induced the fracture process in the buildings and define a support system to stabilize the broadcasting site, a detailed geotechnical survey and a number of numerical slope stability analyses were carried out. One of the main goals of the paper is to underline the effectiveness of the numerical analyses to understand the instability phenomena when they are particularly complex. Furthermore, by using a reliable numerical model with a good understanding of site geology and of the main geotechnical parameters, an evaluation of the slope behavior under different scenarios was made and stabilization measures can be designed.