Abstract: The stability calculation of river closure block is an important basis of river closure design. According to basic formulas obtained from force analysis and experimental research data, the influencing factors of block stability and the applicable conditions of classic formulas for block stability are analyzed. It is pointed out that these parameters as water depth H, vertical velocity coefficient α, relative roughness Δ/D and circumferential motion coefficient ξ should be considered when vertical velocity distribution is not rectangular in the closure gap. Through model tests and project example verification, the practical computing formulas of block stability are put forward for full-width rising and end-dump closure methods in different constructing periods and with different embankment head shapes. The research result is a supplement and improvement to the stability theory of river closure block.

Key words: block for river closure, stability, force analysis, influencing factor, computational formula, measures