Dynamic Response Analysis And Experimental Research For A New Type Of Debris Flow Flexible Protection System

In the northwest and southwest of China,debris flow is a kind of high incidence of natural disasters,which brings heavy loss of the personal and property.Therefore,it is necessary to study the prevention and control of debris flow.Most of the prevention and control projects in China use gravity dams,but gravity dams have disadvantages such as high cost and difficulty in construction.The flexible protection system has been applied to rockfall interception on both sides of highways.It is not only easy to construct but also low in construction cost and easy to rep air and replace.Therefore,the flexible protection system can be applied to the debris flow prevention and control project.Although there was a former,the form was simple and the application scope was small.The dynamic performance of the proposed new flexible protection system is numerically simulated by using finite element software and some working conditions of the scale model are studied.Based on the new flexible protection system,this paper proposes an external network type flexible protection s ystem and uses the same numerical simulation method to study the dynamic performance.The finite element software used in this paper is ANSYS/LS-DYAN,and the dynamic response characteristics of the new flexible protection system and the external network type flexible protection system are studied.Some rules and failure modes are obtained.In order to complete this paper,the preparation and work of the previous work include the following aspects:(1)Reading a lot documentation about the flexible protecti on system and the literature of prevention projects of debris flow.In view of the shortcomings of the flexible protection system applied in the direction of debris flow,a new flexible protection system for debris flow is proposed.Determine and design the size,impact condition and numerical simulation method of the new flexible protection system.To study and analyze the impact velocity,mass and impact position of the impact object,the energy conversion rate,displacement size and regularity of the new flexible protection system,the impact force size and the collision contact time.To study and analyze the impact velocity,mass and impact position of the impact object,the energy conversion rate,displacement size and regularity of the new flexible pro tection system,the impact force size and the collision contact time.The cable diameter,mesh size,and material strength of the system were changed to analyze which diameter and size were the best.It was found that the higher the impact energy,the grea ter the impact force,the greater the displacement,and the higher the conversion rate to internal energy.The smaller the diameter of the wire rope or the smaller the mesh size,the smaller the stress of the structure.Therefore,it is recommended that th e appropriate cable diameter and grid size should be selected in the project.(2)On the basis of the numerical simulation results of the model,the analysis is carried out and the test scheme is designed.The scheme includes the determination of the working conditions,size of the model,the measurement and output of data required for the test.The experiment was carried out,while the test was observed on the side of the test,and the results were analyzed and processed each group of tests.After the experiment is completed,the results are summarized and compared with the numerical simulation results,and the comparison of the obtained laws is consistent,so that the accuracy of numerical simulation is verified.The comparison results show that the regular changes of the experimental and numerical simulation results are the same.(3)On the basis of the new flexible protection system,the external network type flexible protection system is formed by adding ring network,and its numerical simulation is carried out.The influence of the different sizes of the grid size,impact point position and height,impact mass,wire diameter,and impact velocity on the structure was analyzed and compared with the results of the new flexible protection system.It was found that adding the ring network can reduce the displacement and stress concentration.The research results of this paper hope to provide some suggestions and references for the application of the new flexible protection system in the prevention and control of debris flow in the future,and provide some theoretical and data basis for the construction of the project.