Experimental Study On Impact Resistance Of Composite Desk Slabs And Fiber Reinforced Concrete Slabs Under The Rockfall Impact

When the reinforced concrete slabs were strongly impacted by falling rocks,the concrete slabs at the bottom of the slabs break down and fall down which the falling of the broken concrete quickly threatens the equipment and personnel in the structure.When the composite deck slabs were impacted,the profiled sheets at the bottom of the slabs will act as a pocket for the caving concrete to reduce the unnecessary loss.Fiber reinforced concrete improves the tensile strength of concrete and helps prevent concrete slabs from falling down under rockfall impacted.Therefore,it is of great engineering significance to study the impact resistance test of rockfall impact the composite deck slabs and steel fiber concrete slabs.Through the rockfall impact platform,the failure test of the composite deck slabs,steel fiber reinforced concrete slabs and high ductility fiber concrete slabs under rockfall impact was studied by using the test platform.The phenomena,research contents,research work and results after the failure test were summarized as follows.The impact energy and impact speed are changed by changing the height of the drop hammer,and the composite deck slabs were directly impacted by 14m and 10m height to explore the failure mode and impact resistance of the composite deck slabs under the impact of rockfall.The results of the test and the analysis test data were as follows:(1)Compared with reinforced concrete slabs impact phenomenon,when composite deck slabs were impacted by drop hammer,profiled sheets,with high strength and good capability of plastic deformation,can not only effectively consume the energy of falling stone,but also broken concrete block package,to protect structures within the equipment and personal safety after deformation in concrete.(2)In order to compare and analyze the test results under different conditions,a dimensionless parameter impact energy ratio coefficient was introduced.It was found that greater the impact energy,the more severe the damage of the composite deck slabs,and the smaller the impact energy ratio coefficient.The reinforced concrete slabs and steel fiber reinforced concrete slabs and high ductility fiber concrete slabs were impacted by lifting the drop hammer to a height of 14m.By comparing the damage test and analyzing test data of the reinforced concrete slabs,steel fiber reinforced concrete slabs and high ductility fiber concrete slabs under the same impact energy to investigate the resistance of steel fiber and high ductility fiber was added in the concrete slabs,research results were as follows:(1)Compared with the test phenomenon of reinforced concrete slabs,steel fiber concrete slabs bottom surface damage area after being impacted is reduced by 60%to 90%.The bottom surface damage area of high ductile fibre reinforced concrete slabs after being impacted was reduced by 15%to 60%.Although the two fiber reinforced concrete slabs mixed with concrete slabs were broken and collapsed,they can effectively slow down the collapse of slabs during impact.(2)Under the same impact energy,compared with the test data of reinforced concrete slabs,the impact duration of steel fiber reinforced concrete slabs were extended nearly doubled,the peak impact force was reduced by 20%to 55%,and the average impact was reduced nearly 19%～54%.The impact duration of high ductility of fiber reinforced concrete slabs were extended 14%～33%,the wallop peak reduced 10%～53%,and the average impact force was reduced by 14%to 24%.It is shown that both kinds of fiber reinforced concrete slabs can improve the impact resistance of reinforced concrete.