La Fortuna slib stability analysis in Camilo Ponce Enríquez town

Abstract

In the La Fortuna community located in the Camilo Ponce Enriquez canton of the Azuay province in southern Ecuador, a rock and soil landslide was reported that generated a 40 m high and 20 m wide slope. The major conditioning factor for this landslide was the high degree of fracturing of the rock mass that formed wedges and orthogonal jointing favorable to the fall of material.

In this research the rock quality was analyzed using the Bieniawski or Rock Mass Rating (RMR) classification, the slope stability was evaluated using the Slope Mass Rating (SMR) classification and the factor of safety (FS) was determined to design a model to propose alternatives for slope stability. Three families of discontinuities were identified: D-1, D-2 and D-3, which form orthogonal planes to each other, the rock strength was categorized as "Hard" with a value between 50-100 MPa, the RQD value indicates that the rock is of "Regular" quality. According to the SMR classification the landslide slope is "Unstable" and presents planar breakage surfaces and large wedges. The static model indicates that both the interaction between the families of discontinuities D-1 and D-3, as well as between D-1 and D-2 present a safety factor below the minimum required according to the Ecuadorian Construction Norm (NEC), confirming that the slope is unstable.

Corrective treatment is recommended for the slope, which consists of installing drainage to reduce the interstitial pressure between the discontinuities, the construction of walls at the foot of the slope, using shotcrete and applying reinforcements by means of anchor bolts.