Experimental Study On The Cushioning Properties And Dynamic Response Of The Structures Under The Rockfall Impact

With the rapid development of hydropower construction,large hydropower station in the west of our country in a large number of built and to be built,are built by making full use of the terrain of high mountains and canyons.The substations、switching stations often can only be built in the adjacent to the hydropower plant at the foot of the mountain,when the rockfall serious,a threat will be posed to the normal operation of the switching stations and the safety of the staff working in the stations.The power structure is an important node in the power lifeline engineering,once severely damaged or collapsed,caused the comprehensive loss is far greater than the structure itself.The research of the power structure under the rockfall impact is very few at home and abroad,so the study about the cushioning performance of the roof and the side wall protective material and the dynamic response of the structure is quite necessary.This article is made up of the cushioning properties of soil cushion under the rockfall impact by experimental study、the cushioning properties of S steel under the rockfall impact by experimental study and the dynamic response of the power structure under the impact force.The main research contents are as follows:(1)Take the reinforced concrete drop hammer as rockfall,the free fall height of the rockfall is 5 m and 10 m,take the soil cushion laid on the reinforced concrete slab as cushion protective layer,the thickness is 30 cm、40 cm、50 cm,then the acceleration of the rockfall and the impact force of the reinforced concrete slab are changing with the time is know by the impact test,to explore the cushioning properties of different thickness of soil cushion.Shows that with the increase of cushion thickness,the acceleration of the rockfall decreases,the impact force of the reinforced concrete slab also decreases,indicates that the buffering effect of soil cushion increases with the thickness of cushion.Analysis of rockfall acceleration changing over time,theduration of the impact of each condition is near to 0.03 s,using the formula F=ma to calculate the impact force given by the rockfall dropping to the reinforced concrete slab covered with soil cushion.(2)According to the protective of the side wall of the structure,put forward S steel +color plates as a buffer cushion solution,to explore the cushioning properties of the buffer protection system by experimental.Comparison and analysis the test results,obtains the S steel has a good buffer performance.(3)By using the software ANSYS to build a finite element model of the upper reaches of the Yellow River hydropower structure,to analyze the dynamic characteristic of the structure.Then the impact force of the reinforced concrete slab covered with the soil cushion applied to the roof,study the displacement、velocity、acceleration of different position of power structure.Analysis shows that under the different thickness of the cushion,the maximum displacement、maximum velocity、maximum acceleration values of each node is consistent with the moment of occurrence.The dynamic response of the node which the impact force exerted is the largest of each node.(4)By the rule《Code for design of anti-microvibration of multistory factory floor》,taking the displacement and velocity as the main control index of indoor instruments and equipment vibration limits,then evaluating the vibration of the electrical equipment inside the power special structures.The evaluation shows that,the vibration of the outlet building meet the limit requirement.