(1) Chiseling: clear the loose concrete around the opening; The top of the opening forms a 45 degree bevel, which is 30~50 wide; It is necessary to plant reinforcement according to the requirements for reserved openings larger than 100;

(2) Clean the use and arrangement;

(3) Formwork erection: the lower bottom formwork shall be close to the concrete surface, which shall be flat and dense; The parts with waterproof requirements should be supported at the lower part;

(4) After scouring, apply cement slurry at the opening;

(5) The first hanging hole: the height is about 1/2~2/3 of the height of the hole; Pouring compactly; Add proper amount of expansion agent in the fine aggregate concrete where waterproof requirements are required;

(6) Water storage experiment;

(7) The second hanging hole;

(8) Water storage test: if it is unqualified, it is necessary to rework.