Slow landsliding as effect of hydro-mechanical coupled processes: examples of resulting damages and mitigation strategies

The paper is concerned with the diffuse occurrence of movements in natural clay slopes that are from very slow to slow and that, at times, undergo accelerations bringing about significant damages of structures and infrastructures in interaction with the slope. Four study cases are treated in the paper, showing by means of both in situ monitoring and mathematical modeling that such slope movements are effect of sliding processes along either pre-existing or newly developing shear bands, as part of progressive failure processes resulting from evolving equilibrium conditions. The evolving deformations are controlled by slow variations of the effective stresses, largely associated to the hydro-mechanical coupling taking place in transient flow processes. Also, the lack of mitigation measures is shown to cause severe increase of the depth and extension of the landslide bodies, with a dramatic increase of the damaged structures and cost of final emergency measures.