Injection of Non-Conventional Binders to Improve Geomechanical Properties of Cataclasite

During Tunnel Boring Machine (TBM) excavation in hard rock, it is possible to encounter at the excavation zone, weak areas composed by weathered rocks, which need to be improved. In this paper, a laboratory study about a grouted cataclasite fragmented rock and its mechanical behavior is reported. Two non-conventional binders, that is, a colloidal silica with 15% SiO2content and very low viscosity and a two-component low-viscosity hydrophilic acrylic resin (both about 3 mPas) were tested in laboratory to evaluate their performance improving the cataclasite. Permeation tests in a column of 0.5 m height and 0.05 m diameter were performed. The cataclasite was placed loose in the column, with a porosity n = 0.6 and the two products were injected with a pressure between 3.5 and 4 bars. After that, multi-stage triaxial CU on single samples for each grouted product with 100 mm height and 50 mm diameter. Strain rate of 0.3 mm/min was applied. Results show that the binders are valid products to improve the mechanical properties of cataclasite.