Experimental investigation on pneumatic pre-fracturing grouting in low-permeability soil

Abstract

Effective injection of grout into low-permeability soil is difficult in the process of soil reinforcement. To address practical problems, this study proposes a pneumatic pre-fracturing grouting method comprising model experiments to analyze the initiation and propagation of fractures, earth pressure, soil displacement, and the characteristics of grouting consolidation. In the pneumatic fracturing experiment, the fractures exhibited larger effective radii under gradual pneumatic loading compared with those created due to instant loading, providing more initial channels for grout diffusion. Meanwhile, the higher the pneumatic pressure, the greater the residual height of the fractures after pneumatic fracturing, yielding a predominant condition for grout injection. Compared with conventional grouting, the effective injection amount, effective diffusion radius, and height of grout consolidation of pneumatic pre-fracturing grouting were much larger. The results prove the feasibility and superiority of pneumatic pre-fracturing grouting in low-permeability soils.