The San Leo Cliff (Italy): stability conditions and remedial measures

The ancient town of San Leo rises on the top of a rock butte consisting of calcarenites and sandstones overlying a more deformable substratum formed by clay shales. Since historical times, the marginal areas of the town have been threatened by rock failures in the cliffs which are strongly influenced by the evolution of the clay shale slope. The paper illustrates the results of the geomechanical characterization of the clay shales and of the rock formations. The criteria adopted for the stabilization of the rock cliffs and of the underlying clay slope and the preliminary results of the monitoring instrumentation are also discussed.