落石冲击荷载计算方法研究OA

To clarify the relationship between rockfall impact force and impact load in civil engineering,a comprehensive reflection coefficient is introduced to reflect the interaction between falling rocks,cushioning soil layers,and structures(a higher value indicates a more significant impact effect on the structure).A rockfall impact load calculation method based on wave theory is proposed.The size and distribution characteristics of rockfall impact loads were studied through experiments on arched structures with overlying cushioning soil layers subjected to rockfall impacts.The values and influencing patterns of the comprehensive reflection coefficient were obtained.The proposed calculation method was used to analyze the relationship between rockfall impact loads and rockfall impact forces.Through the research,it was clarified that the rockfall impact load on the structure presents a symmetrical parabolic distribution on the cross-section and can be characterized by a quadratic parabolic curve equation controlled by the maximum impact pressure peak at the arch crown and the structural span.The results indicate that within a range of 10 meters of free fall height for falling rocks and a cushioning soil layer thickness of 2.0 meters,there is a significant negative correlation between the comprehensive reflection coefficient and the thickness of the cushioning soil layer.When the thickness of the cushioning soil layer is 2.0 meters,its influence on the shape and free fall height of the falling rock is relatively small,and a value of 0.55 can be used.When the thickness is 1.0 meter and 0.5 meters,the comprehensive reflection coefficient of cuboid falling rocks is greater than that of spherical or conical falling rocks,and it is positively correlated with the falling height of the rocks.The relationship between the resultant force of rockfall impact loads on the structure and the impact force of rocks on the cushioning soil layer depends on the thickness of the cushioning soil layer and the shape of the falling rocks.When the thickness of the cushioning soil layer is 2.0 meters,the two are close,with the former slightly smaller than the latter,making the resultant force of rockfall impact loads equal to the rockfall impact force on the structure,which leans towards safety in structural design.However,when the thickness of the cushioning soil layer is less than 2.0 meters,the reverse is true,and the smaller the thickness,the greater the difference.When the thickness of the cushioning soil layer is 1.0 meter,the average increase of cuboid falling rocks is about 20 times larger than that of spherical or conical ones,and when the thickness is 0.5 meters,the average increase is about 30 and 10 times respectively for the two shapes.Under the same conditions,the resultant impact load of cuboid falling rocks is greater than that of spherical or conical ones,and the difference between them increases as the falling height of the rocks increases or the thickness of the cushioning soil layer decreases.