Grouted gravel pile is a new technique of soft soil improvement.The reinforcement of the pile is realized mainly by the grouting and the improvement of the surround soil induced by the grouting permeation

then settlements of composite foundation can be reduced.Considering the permeation of the grout into clay soil around the grouted gravel pile

the calculation formulas for impacted range of the grout and the modulus of the compression in grouted zone were obtained.The obtained formulas were verified based on model tests.In consideration of the grout permeation

the quantitative analysis of the impacted range by grouting was carried out and the calculation formulas of effectively reinforced soil radius were obtained by numerical analysis

which can give a reference to the engineering design.