Dynamic Response Analysis for Debris Flow Dam with Sediments

The Wenchuan strong earthquake caused the mountain to break, and triggered a large number of landslides to accumulate in the slopes and channels. This provided a huge amount of loose solid sources for the formation of debris flows, which greatly reduced the threshold rainfall for the initiation of debris flows, and sharply increased the frequency of outbreaks, which became the main type of secondary disasters. Under the effect of multiple debris flows, the debris flow dam will be partially or completely filled-up, and the function of disaster mitigation has been reduced. However, there is inadequate research on the effects of sediment deposits behind the dam on the debris flow dam disaster reduction. In this study, based on the weakly compressible smooth particle flow (SPH), the Drucker−Prager (DP) criterion and the Herschel−Bulkley−Papanastasiou (HBP) rheological model are used to simulate the dynamic process of the interaction between the debris flow and the sediments behind the dam. The proposed method is verified by a flume experiment. On this basis, the model is further used to simulate the dynamic process of the Hongchungou debris flow disaster under sediments behind the dam. The research results show that the deceleration rate of debris flow through the dam is 31.6% under the condition of empty reservoir, the half storage conditions is 16.4% and 6.5% for full reservoir conditions. The sediments reduce the peak clipping effect of the dam, which significantly reduces the blocking effect. At the same time, the sediments behind the dam changes the dynamic response of the debris flow dam. Under the empty storage the debris flow shows the processes of dam hitting, climbing, and siltation, however the full storage shows the debris flow entrained by the siltation body passing the dam. In addition, the peak impact force at the bottom of the dam under the half-reservoir condition is reduced by 13.25% compared to the empty reservoir condition, and the peak impact force at the top of the dam under the full-reservoir condition is 1.75 times compared to the empty reservoir condition. The research results can provide a basis for debris flow dam design. Copyright ©2021 Advanced Engineering Sciences. All rights reserved.