To solve the problem of surface lifting caused by grouting in urban shallow underground projects

grouting lift calculation method and simplified algorithm were established based on the theory of stochastic medium

and effects of compaction grouting and fracture grouting on surface uplift were studied. Through PFC simulation and laboratory model experiments

the suffering area of the surface uplift by ball compaction grouting and horizontal fracture grouting were studied

and the accuracy of the grouting lift calculation method of surface uplift displacement was verified. Effects of grouting depth

soil dry density

and soil water content on surface uplift during grouting were investigated by introducing the grouting uplift coefficient γ. Results show that the simplified method of theoretical prediction of surface uplift displacement was accurate when the depth of grouting was greater than 2 m

and it was not applicable when the depth of grouting was less than 2 m. The surface uplift caused by the two grouting methods was consistent with the results of the numerical simulation and the mathematical model calculation. Single hole grouting changed the displacement field of the overlying inverted cone soil. The maximum surface displacement caused by compaction grouting was large

so was the influence range of fracture grouting on the surface. Factors such as grouting depth

soil dry density

and soil water content all influenced the maximum surface displacement caused by grouting

among which grouting depth was the most important factor.