Abstract:
The normal coefficient of restitution (
Rn) is the most critical input parameter in the prediction and analysis of rockfall disasters. Because of its many controlling factors, how to determine an accurate and reasonable value of
Rn is still a difficult problem. In order to explore the law and mechanism of the joint influence of multiple factors on
Rn, the response surface methodology-central composite design method is used to investigate the combined effect of seven factors on
Rn for the first time. Through regression and variance analysis of the test results, the seven selected factors have the significant effects on
Rn, and the order of significance is the impact angle (
θ) > block hardness (
H1) > rotational speed (
ω) > shape factor (
η) > incident velocity (
V) > slope hardness (
H2) > size (
d). Many interaction parameters also show the significant effects on
Rn, in the order of
d−θ >
H1−d >
V−η >
H1−ω >
d−η >
η−ω >
H1−η. For a single factor parameter,
Rn increases with the decrease of
d,
V,
η,
θ and the increase of
H1,
H2,
ω; for interaction parameters,
d and
ω have a weak effect on
Rn, only when
H1 is small, and the effect gradually increases with the increase of
H1;
η has a significant effect on
Rn when
H1 is small, and the effect significantly decreases with the increase of
H1; when
η is small,
Rn increases significantly with the decrease of
V or
d, and this effect is not significant when
η is large; when
θ is small,
Rn decreases rapidly with the increase of
θ, and the decreasing trend slows down when
θ is large. Compared with block with small
η, the
ω of block with larger
η has a more significant effect on
Rn. These conclusions can provide an important reference for the construction of the
Rn calculation model of rockfall, and provide a basis for the accurate prediction and prevention of rockfall disasters.