Stability analysis of check dam impacted by intermittent surge

Viscose debris flows always move in the manner of intermittent surges and show obvious fluctuation. In the traditional design of debris flow control engineering, the impact of single surge has on the check dams was the only factor to be taken into consideration. Whereas stability variation law of the check dams under the impact of intermittent surges was always neglected. On the basis of debris flow observation material from the Jiangjia Gully (JJG), we initially analysis the fluctuating and decaying characteristics of intermittent surges. Results indicate that intermittent surges exhibit obvious decaying characteristics and finally decay in a power-law form, showing a strong no-linear behavior. Next, based on loading combination and stability analysis of check dams, we deduced the expression of the stability coefficient when intermittent surges impact on the check dams in empty and half reservoir conditions. Meanwhile, stability variation law of the check dams in the different conditions were compared. Results indicated that when intermittent surges impact on check dams, anti-sliding stability coefficient (K_c) and anti-overturning stability coefficient (K_y) decrease with the increase of surges, and the former 3^th~5^th surges experienced the largest decaying rate. On the other hand, the deeper deposits in the reservoir corresponds to the smaller stability coefficient under the impact of the same intermittent surges. Finally, the relationship between flow depth and stability coefficients is in the form of an envelope curve, inferring that the variation of flow depth restraint the stability coefficient of check dams.