Improvement in nailing systems for coarse soils

Abstract: Some aspects of the performance of two different techniques for the temporary support of an excavation face are investigated. The first technique is a traditional soil nailing consisting of a fibreglass bar element embedded in cement based grouting. The second technique differs from the first in the addition of an external sheath devised to contain the injected grout. The effectiveness of the ground treatment is investigated by pullout tests carried out on a sandy gravel deposit. An interpretation of the problem of grout injection is also attempted on the basis of the analytical solution of a pressure controlled injection in a circular hole, in an isotropic elasto-plastic medium in plane strain conditions. The experimental and analytical results permit getting some insights into the main characteristics of the interaction problem between the injected grout and the surrounding soil.