Impact Response Characteristics of Apron Structure to Bouldery Debris Flow

Apron is a commonly used structure in the downstream of debris-flow-retaining dams. Its function is to resist the impact and erosion of debris flow on the dam foundation. In order to enhance the impact resistance of the apron to boulders, increasing the apron thickness and filling the block stone are usually adopted. However, the apron is still often destroyed by bouldery debris flow. Therefore, we propose a kind of toughness apron. Physical test and numerical simulation are used to reveal the dynamic response of the toughness apron. The results show that both tire cushion and stone cushion can buffer the impact of boulders. The physical test showed that the cushion reduces impact force and vibration acceleration, and the numerical simulation results indicate that the cushion significantly reduces damage to the protection apron while dissipating most of the energy. It was also found that there is an energy threshold of impact damage resistance of the apron. When the impact kinetic energy is higher than this threshold, the apron will be damaged. These findings highlight its potential for debris flow protection. According to the corresponding impact characteristics of the dam, the design method of the toughness apron is proposed.