In order to analyze the mechanical mechanism of compression grouting and give the analytical solution of the ultimate grouting pressure

the process of compaction grouting is considered as the question of cavity expansion in infinite soil mass. The ultimate grouting pressure is given by the law of conservation

in which the volume change of cavity expansion is balanced with the compression of soil and the energy given out from cavity expansion is absorbed by the volume change and shear strain caused in soil. The stress-strain-volume change relationships under the high stresses caused by compression grouting are described. The theoretical values agree with the measured values from the field test; and the conclusion that the grouting pressure of columniation cavity is higher than the sphere cavity is gained.