On the bases of the plastic mechanical mechanism and the large strain

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 two zones. The deformation following little deformation in elastic zone and large-deformation in plastic zone is taken into consideration. The initial fracturing grouting pressure is the limited expansion pressure and the second fracture grouting take place when the large and small stress of soil is conversion. On the bases of the stress equilibrium equation and continuous boundary condition of stress and deformation

the stress distribution in the elastic-plastic zones

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

the result of the present theory is very near to that of the engineering practice.