Abstract: Based on the theory of plastic mechanics and large deformation, considering the hole expansion problem of Drucker-Prager modified criterion, an analysis model of loess splitting grouting pressure is established. The small deformation theory is adopted in the elastic zone and the large deformation theory is adopted in the plastic zone. The theoretical solutions of the stress field and displacement field of the elastic and plastic zone around the grouting bubble are derived. The analytical solutions of the radius of the plastic zone and the starting grouting pressure are studied. Finally, the engineering example is used to demonstrate. The results show that Based on the theoretical model of circular cavity expansion considering D-P correction criterion, the radial stress and circumferential stress show a nonlinear decreasing relationship with the increase of r_u/r_P. Under undrained condition, with the increase of soil material parameters (c、φ、E、ν), the splitting pressure increases nonlinearly when the slurry splits the soil vertically and horizontally. The theoretical calculation value is 514.2~693.7 kPa, which is close to the measured value of 430~780 kPa. It shows that the theoretical analysis method has a certain practical value in the splitting grouting project in loess area.

Key words: unsaturated loess, fracturing grouting, cavity expansion, D-P revised criterion, pressure estimation