Experimental Study On Rockfall Impact Failure Mechanism Of Reinforced Concrete Slab

Collapse of the Rolling Stones disasters is one of the common geological disasters in western mountainous area of our country,with a sudden,unpredictability,harm serious etc.Collapse of the Rolling Stones caused serious damage to structurefes and hunab activity within the scope of where it can reach.Along with the Development of the Western Regions strategy implementation,a targe number of roads,railways,bridges,tunnels and a series of infraslructure construction will be built in western mountains,In order to control the collapse damage caused by the high-speed impact on structure,people often shade the buildings,Such as casing hole as collapse hazard mitigation works Rolling Stones.The domestic researche on the basis of rolling disaster were weak and there is no reference standard for the design of the rolling stone proteetive stucture Therefore to carry out the rock fall impact failure mechanism of concrete plate under experimental study is very necessary and urgent.This arliele based on different speed of rock fall impact cases;study the fail ure mechanism of reinforced concrete plate,so as to provide reference for rolling stone protective structure design.There are varieties of dynamic damage models under impact load,the deformation and failure behavior of complex relations with variables such as stress,,strain rate,the yield coundition,flow stress,the strain rate effect,historical effect of strain rate and so on.Through different height rock fall contact-collision-free fall impact damage the whole process-rock fall rally-concrete slab vibration test research discuss different impact speed cases,failure modes and failure mechanism of reinforced concrete plate bearing.Test content mainly includes:1)High speed impact test.The height of rock is 13 meters(Drop speed 15.96 m/s);2)Medium speed impact test(Drop speed from 4.43m/s to 9.90m/s).3)The low speed impact test.(Drop speed from 1.40 m/s to 2.42m/s).The main results are as follows:(1)The rock drop from 13meters height to destroy reinforced concrete slab,phenomenon is obvious.The damage area of approximate ellipse shape,and the wall is smooth.Failure process can be divided into three stages:small disturbance caused by stress undulation;with broken caving process caused by large amplitude vibration and subsequent vibration caused by spring back and drop back.(2)The rock drop height from 5meters to 1 meters produced different degree indentation on the slab surface;the surface is mainly for different fracture group.Hammer acceleration and reaction force under different height is not a linear relationship.Under different mass of drop,the impact of hammer acceleration and strain response is bigger,and relatively small effect on counteracting force.(3)Summarize the influence of different height when it impacted by the rock,which showed different results.According to acceleration time-distance graph and force time-distance graph also,this article come up with a refined concrete destroy speed.High speed impact damage is penetrable.Medium speed impact damage of rock fall caving zone adjacent to medium disturbance is larger,there are much more cracks around the caving zone.Low speed impact caused no damage,which can be thought as the vibration phenomenon of the elastic range.