High-arch-dam flood discharge and energy dissipation structure of narrow river valley and deep tail water

The invention discloses a high-arch-dam flood discharge and energy dissipation structure of a narrow river valley and deep tail water. An upper-layer hole and a lower-layer hole are distributed on a dam body; two dams do not need to be arranged at the downstream of the dam to form a closed water cushion pool; and only a concrete apron and revetments at two banks need to be arranged. The upper-layer hole adopts combined outflow of an overlooking angle with a small angle and a depression angle with a small angle; and the lower-layer hole adopts narrow seam type outflow of a flat bottom angle, two-side shrinking and vertical dispersion, and discharged water flows of the upper-layer hole and the lower-layer hole are not collided in the air. The two paths are not arranged; and the outflow of the upper-layer hole is controlled to be the smaller angle so as to control the degree and the range of a drop point and atomization of a water tongue. According to the high-arch-dam flood discharge and energy dissipation stru