Stability analysis of check dam impacted by intermittent surge

Viscose debris flows always move in the manner of intermittent surges and show obvious fluctuation. The impact of single surge has on the check dam was the only factor to be taken into consideration in the traditional design of debris flow control engineering, whereas stability variation of the check dam impacted by intermittent surges was always neglected. On the basis of debris flow observation material from the Jiangjia Gully (JJG), we initially analyzed the fluctuation and decaying characteristics of intermittent surges. Results indicated that intermittent surges exhibit obvious decaying characteristics and finally decayed in a power law form, showing a strong nonlinear behavior. Next, based on loading combination and stability analysis of check dam, we deduced the expression of the stability coefficient when intermittent surges impact on the check dam in empty-storage and half-storage reservoir conditions. Meanwhile, stability variations of the check dam in the different work conditions were compared. Results indicated that when intermittent surges impacted on check dam, anti-sliding stability coefficient ( K c ) and anti-overturning stability coefficient ( K y ) decrease with the evolution of surges, and the former 3th ~ 5th surges experienced the largest decaying rate. On the other hand, the deeper deposits in the reservoir corresponded to the smaller stability coefficient under the impact of the same intermittent surges. Finally, the relationship between flow depth and stability coefficients was in the form of an envelope curve, inferring that the variation of flow depth restraints the stability coefficient of check dam.