A Study of a Road Landslide in Puerto Rico

Numerous landslides have plagued the construction of a 1.3 mile road sector in the mountainous region of central Puerto Rico. The area is underlain by a sequence of landslide deposits overlying a muddy limestone and hard overconsolidated clayey soils. Landslides have occurred in both cuts and fills that have delayed the road construction for a period of more than two years, bringing as a result, great economic losses for the Puerto Rico Highway Authority. The landslide trigger mechanism has been intimately related to high rainfall, commonly observed in this region. The geotechnical and geological studies performed previous to the construction of this road sector were few and meager. These studies did not recognize the presence of unstable deposits along the road sector alignment. As a result, several large slope failures developed during construction that halted the completion of the road. For investigating the slope failures, detailed geological and geotechnical studies were performed, including monitoring of groundwater levels, rainfall, and slope movements followed by laboratory and slope stability analyses. Remedial measures have been provided in the form of excavation, drainage, and stability berms. Renewal of the road construction with the remedial measures is prompt to start