The rapid-setting two-component chemical grout needs to be achieved by static mixing

resulting in temporal and spatial variations in grout viscosity. We used poliurethane/water glass grout as the typical rapid-setting chemical grout. We studied the permeation grouting mechanism considering space-time variation in viscosity. We conducted the time-varying viscosity test of rapid-setting chemical grout. We derived equations for one-dimensional permeation grouting that describe the space-time distribution of viscosity

permeation motion

and the evolution of grouting pressure. We further derived equations for three-dimensional spherical and cylindrical permeation grouting that describe the space-time distribution of viscosity

permeation motion

and the evolution of grouting pressure. We established a theory of spherical and cylindrical permeation grouting

taking into account the space-time variation of viscosity. We compared the results of laboratory experiments and numerical simulations with the derived theoretical equations. According to the results

the viscosity of rapid-setting chemical grout increases exponentially with time. Compared with the traditional Karol permeation grouting theory

the permeation radius predicted by our grouting theory was closer to the experimental results. The described permeation grouting phenomenon aligned well with the numerical simulation results. The experimental and numerical data collectively validate the precision and accuracy of our proposed theory.