Precipitation Influence on the Distribution of Pore Pressure and Suction on a Coastal Hillside

The frequent interruption of roads in some freeways in Brazil due to slope failure has caused economic losses and potential harm to users. The paper presents data from a monitoring system installed at Serra do Mar in Santa Catarina State, Brazil. The slope monitored is called Morro do Boi and is located on BR-101 south, near the municipality of Itapema. It was stabilised using anchor and flexible metal mesh. Hence, all the pore water pressure measured is due to environmental changes. After approximately sixteen months of readings, it was possible to observe that the suction variation in the unsaturated layers presents a time delay in relation to the rainfall observed in the area. The ground water table presented a variation of about 1.5 m. The analyses of the data allowed establishing a trigger accumulated rainfall that reduces the negative pore water pressure to values below 10 kPa. So far, no significant positive pore water pressure has been observed above the ground water table.