Method for strengthening foundation through horizontal grouting holes

The invention discloses a method for strengthening a foundation through horizontal grouting holes. The method includes the steps that (1) vertical drill holes are distributed around an existing building subjected to fitting strengthening; (2) binary grout is injected into the vertical drill holes; (3) the horizontal grouting holes are drilled in the depth positions, needing grouting and strengthening, in the vertical drill holes, and the multiple rows of horizontal grouting holes can be distributed in the vertical direction within the range needing strengthening; and (4) grouting can be carried out directly through drill rods of a drilling system, or steel wire mesh framework plastic composite pipes are installed in the holes to serve as grouting pipes after the drill rods are pulled out, the demand for repeated grouting can be met by adopting the steel wire mesh framework plastic composite pipes as the grouting pipes, and the grouting pressure adopted in the grouting process is determined according to the de