The main reasons for the spillway accident are

The main reason of spillway accident is the insufficient discharge capacity of spillway.

Spillway is a flood control device for water conservancy buildings such as reservoirs, and most of them are built on one side of the dam, just like a big sink. When the water level in the reservoir exceeds the safety limit, the water will flow downstream from the spillway to prevent the dam from being damaged. Comprises a water inlet channel control part, a drainage channel and a water outlet channel.

The open or overflow drainage structure with breast wall entrance is used to discharge the flood that cannot be contained in the planned storage capacity and ensure the safety of the dam. Spillways usually don't work, but they are important buildings of reservoir hub. According to the flood discharge standard and operation conditions, spillway can be divided into normal spillway and emergency spillway.

The former is used to discharge design flood, and the latter is used to discharge extraordinary flood. According to the location, it can be divided into riverbed spillway and shore spillway. Whether the design and layout of spillway is reasonable not only directly affects the safety of reservoir, but also affects the cost of the whole project. Earth-rock dams are generally small and medium-sized spillway, accounting for about 25~30% of the project cost and 25% of the labor force.

Therefore, the reasonable layout and selection of spillway is an important link in reservoir engineering design. Key words: common problems of spillway in small and medium-sized reservoirs of earth-rock dams Countermeasures Whether the design and layout of spillway are reasonable directly affects not only the safety of the reservoir, but also the whole project cost.

Generally speaking, the small and medium-sized spillway of earth-rock dam accounts for about 25~30% of the project cost and 25% of the labor force, so the reasonable arrangement and selection of spillway is an important link in reservoir engineering design. Spillway is an important facility to ensure the safety of reservoir during flood season.

Due to the limitation of engineering cost, the flood standard and flood data used in the design of small and medium-sized reservoirs are often low, which will inevitably lead to the small design size of spillway. Coupled with the weathering and collapse of surrounding rock mass, the discharge capacity is often insufficient, and the flood discharge safety cannot be guaranteed.