Comportamento de uma escavação com cortina ancorada e grampeamento em solo residual com camadas reliquiares

Abstract

The research analyzed the behavior of a monitored excavation in gnaissemigmatite residual soil with high NSPT. This soil maintains the reliquiae structure of the parent rock, with intercalated layers of diverse resistance and had an unfavorable inclination to the stability of the excavation. The resistance of one layer was considerably inferior to the others. The excavation was initially predicted in two levels of anchored walls, but presented nonconformity at the end of the construction of the first level. Excessive deformations were found leading to a crack parallel in the hilltop of the anchored wall, which measured 30 m of extension and 0.23 m of aperture. Considering the presence of low resistance soil layers, a new project was performed to accomplish the advance of the excavation with soil nailing. Soil mass movements and loads of nails and anchors were monitored in two sections, which had different heights and inclination of the reliquiae layers. Significant lateral movements were observed with different deformation patterns, which are generally not described in the literature. The loads observed in the nails approximated to the corresponding active condition, taking the post-peak resistance of the soil. Due to the smaller inclination of the layers, the greater deformations and tensions were verified in the section of smaller height. The reliquiae soil layers were fundamentally important in the behavior, which was strongly influenced by the direction and inclination of these layers in relation to the face.