This paper presents a case study of 18-m-high rock slope failure triggered by the action of groundwater during rainy season. Aiming to understand the behavior of the slope under consideration, field investigations, monitoring and theoretical analyses were undertaken. Persistent joints, dipping out of the slope face, form potentially unstable sliding blocks. In discontinuities, water exerts hydrostatic pressure. The use of the Coulomb method was able to adequately represent the slope stability conditions. Stability analyses highlight the importance of the groundwater table (GWT) in the slope stability. Precipitation and climatic regime influenced slope stability by modifying properties of the rock, in particular of the discontinuities, and varying the GWT. Long-term GWT and rainfall monitoring contributed to the understanding of groundwater flow behavior.
Planar or wedge failures in rock slopes are a traditional problem in Rio de Janeiro and many construction works are carried out on account of these. Mostly, the failure is associated with intense rainfalls. This paper presents a case of rock slope failure located at km 106 of the Brazilian Federal Highway 116, Rio de Janeiro/RJ (BR-116/RJ), triggered by the action of groundwater during rainy season (Figure 1), on November 13th 2016.
Aiming to understand the behavior of the slope under consideration, field investigations, monitoring and theoretical analyses were undertaken. The fracture system mapping was performed by rotary drilling and the topography of the failure and adjacencies. Six holes were drilled, totaling 130 m of drilling. Rainfall monitoring was carried out at pluviometric station located near the site (BR-116/RJ, km 105). Rainfall was monitored with rain gauges. The readings were made automatically with bucket size 0.2 mm, and the data was transmitted via GPRS technology. The groundwater table (GWT) were monitored periodically by means of six water level meters (WL). The WLs were installed in holes of rotary drilling. Statistical analyses were performed to understand the correlation between the measured data. Stability analyses were carried out assuming a rupture mechanism inferred from the geological-geotechnical characteristics of the slope. Figure 2a shows the topography of the rock slope and location of the WLs and Figure 2b shows the cross section under study in a photograph.
