Abstract: Control of soil deformation induced by tunnelling is one of the major objectives of fracturing grouting. Prediction accuracy of tunnel deformation depends mainly on the equivalent elastic parameters of composite soils with fracture grouting. Firstly, according to equivalent grouting area and the existing model of fracturing grouting, a simplified 2D model for equivalent unit cell is developed for composite soils with fracturing grouting, and the analytical solutions of the equivalent elastic parameters of this model are derived based on deformation compatibility principle and homogenization theory. Secondly, finite element method is employed to calculate and analyze the equivalent elastic parameters of the simplified model and existing model, respectively; meanwhile, the comparisons are made between the finite element and analytical results of the simplified model. Lastly, the influence of grouting volume ratio, soil elastic parameters, and grouting concretion elastic parameters on equivalent elastic parameters are analyzed by means of the analytical solution. The results indicate: (1) the equivalent grouting area method is feasible, and the simplified model can be applied to theoretical analysis in the elastic deformation stage; (2) the analytical results are in good agreement with the finite element results, and hence the analytical results are reasonable; (3) the equivalent elastic modulus and equivalent Poisson’s ratio of composite soils are mainly influenced by the grout volume ratio and modulus of grouting concretion body; the Poisson’s ratio of grouting concretion has slight influence on the equivalent elastic modulus of composite soils.

Key words: fracturing grouting, composite soils, elastic modulus, Poisson’s ratio