| Debris flow is a common geological hazard.When the disaster occurs,the impact of boulders and stone in the debris flow is one of the main causes of damage to buildings and structures.In this paper,the boulder and block disasters in the small mudslides in some small areas of Gansu Province are serious.The idea of “water-stone separation” in the prevention and control of debris flow disasters and the high-strength steel strand of Cable net,which is used in the Large Span Spatial Structures.A new block structure system--steel tube column-cable net system is proposed to resist the impact of debris blocks.In this paper,theoretical analysis,numerical simulation of ANSYS/LS-DYNA and experimental research methods are used to explore the dynamic impact response of the steel tube column-cable system under the impact load of debris flow and massive rocks.The specific research contents are as follows:(1)The steel tube column-cable net system is proposed.The finite element analysis of a single cable in the system is carried out to explore the dynamic response of steel strands with different length under impact loads under fixed constraints at both ends.Different element types are used to simulate a single steel strands,and the peak values of impact force and displacement at impact point are compared to determine the appropriate element to simulate the strands.The steel tube in the system is simulated and analyzed to explore the dynamic response of different wall thickness,different impact velocity and different impact height under impact load.The results show that the thick-walled steel tube has good impact resistance.For one kind of structure in the steel tube column-cable net system,that is,three kinds of two steel tube-cable net structures and one three steel tube-cable net structure,the impact response under impact load is explored,and the failure mode of the structure is obtained.(2)Through the parameter analysis of a kind of structure in the steel tube column-cable net system,the time-history response of impact force,peak value of impact force,peak value of displacement and peak acceleration,time-history response of axial stress near the impact point of steel strand,the change of stress and strain of steel tube and and the failure mode of structure under different parameters(different cable types,different diameter of steel strand,different wall thickness of steel tube and different yield strength of steel tube)are obtained.The dynamic response and failure modes of the supported steel tube column-cable net structure and concrete-filled steel tube-cable net structure under impact load are studied.The peak value of impact force of braced structure and concrete-filled structure is larger than that of one kind of structure in the system,and the peak value of displacement is smaller.(3)Using the self-designed impact test platform,the impact tests of two steel tube-cable net structures,two steel tube-cable net structures with lateral support,three steel tube-cable net structures and three steel tube-cable net structures with lateral support were carried out.The DHDAS dynamic signal acquisition and analysis system is used to analyze the dynamic strain,displacement and acceleration of key measuring points of the structure.Through data analysis and comparison of the peak displacement and acceleration in the finite element simulation results,the two laws are consistent,which verifies the rationality of the steel tube column-cable net system. |
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