In order to analyze the mechanical mechanism of fracture grouting during the early phase by using the theory of large-deformation and plastic mechanics

the early phase of fracture grouting is regarded as the question of cavity expansion in infinite soil. The stress distribution due to the cavity expansion in soil is considered as three zones. The deformation following little deformation in elastic zone and large-deformation in plastic zone is taken into consideration. On the bases of the stress equilibrium equation and continuous boundary condition of stress and deformation

the stress distribution in three zones

the terminal radius and grouting pressure are obtained. According to the compassion

the results of the present theory is very near to the outcome of the engineering practice.