Heightening and strengthening structure and method for in-service steel bar concrete retaining wall

The invention provides a heightening and strengthening structure and method for an in-service steel bar concrete retaining wall. The structure comprises the in-service steel bar concrete retaining wall, a strengthening vertical plate is arranged on the upper portion of the in-service steel bar concrete retaining wall, and the in-service steel bar concrete retaining wall is connected with the strengthening vertical plate through embedded steel bars; a horizontal pressure reduction unloading flat plate is arranged on the bottom of the strengthening vertical plate, the horizontal pressure reduction unloading flat plate is located above the wall back of the in-service steel bar concrete retaining wall, and injection pipes or mini piles are arranged on the lower portion of the horizontal pressure reduction unloading flat plate; a kick plate is further arranged between the strengthening vertical plate and the horizontal pressure reduction unloading flat plate. The method comprises the steps of construction preparat