Análise da eficiência do uso de grampos verticais em estruturas de solo grampeado

Abstract

Soil nailing structures are structures that enable vertical or sub-vertical cuts, allowing a greater use of space. This type of structure is present in urban, road and railways, for example. Through the insertion of nails in the soil mass increases the safety factor against the slope rupture and in this way it is possible to maintain cuts in the subvertical or even vertical stability. In the classic technique the nails are positioned in the sub-horizontal position. In Brazil, some companies have recently been used the procedure in the subvertical or vertical position near the face of the structure. The aim of this variant of the classical technique is to increase the stability of the massif, reducing the final horizontal deformations and during the excavation and also increase the safety fator against rupture. The aim of this research was to verify the efficiency of the use of vertical nails positioned close to the face, verifying if these nails contribute to reduction of the traction generated in the sub-horizontal nails, reduction of the horizontal deformations of the face and increase of the factor of safety of the structure. To model the structures will be used the finite element program Plaxis 2D and Plaxis 3D. To analyze the safety factor it will also be used the program Slide based on equilibrium limit. The results for some analyzes, some with usual rigidities and others with lower rigidities, to verify if a less rigid system undergoes significant changes with the introduction of vertical nails, since a very rigid system can make the use of vertical nails inefficient. The results showed that there were significant gains for the reduction of horizontal displacements and traction in the sub-horizontal nails, but for this it was necessary to use a very high number of vertical nails, which may not be economically feasible.