Study On The Dynamic Response Of A New Gabion Retaining Structure Under Impact Loading

Debris flow is one of the most dangerous natural disasters that occur in mountainous areas around the world.China’s mountainous areas cover a large area and cause a large number of casualties and infrastructure damage every year.In order to reduce the degree of damage caused by debris flow to downstream living areas,scholars have mainly carried out research in the following aspects: the disaster mechanism of debris flow,the hazard prediction,monitoring and early warning,risk assessment and risk manage,influence of natural factors(climate,meteorology and hydrology,etc.),and controlling catastrophic techniques.Tanchang is located in the Loess Plateau area,and the county is often affected by debris flow disasters.According to the local geological and geomorphological features,this article puts forward a new gabion retaining structure.It has many advantages such as good flexibility,strong seismic performance,high water permeability,low cost,local materials and simple construction.It provides a new idea for the prevention and control of debris flow in remote mountainous areas.In this article,with the help of ANSYS/LS-DYNA finite element software,we explored the impact resistance of the new gabion retaining structure and the influence law of various factors on the dynamic response of the structure.Details are as follows:(1)ANSYS/LS-DYNA was used to establish a finite element model of gabion cells.The results of the finite element analysis are compared with the available experimental values.It is proved that the dynamic finite element software is reasonable for the dynamic analysis of the gabion cell.It provides a technical basis for the analysis of the dynamic response of the new gabion retaining structure in the future.(2)The impact resistance of the new gabion retaining structure and the traditional slurry masonry retaining structure were compared and analyzed with the help of ANSYS/LS-DYNA software.The impact force,support reaction force,structural acceleration and boulder acceleration of the new gabion retaining structure are smaller during the impact.However,the duration of its effect is longer and the displacement of the observation point is larger.Compared with the traditional slurry retaining structure,the stress wave spreads to the whole structure faster and the structure deforms more uniformly after the boulder impacts the new gabion retaining structure.All parts of the new structure are involved in energy dissipation,and the performance of the material is fully utilized.At the same time there is a part of the displacement time curve where the peaks and troughs meet in the new gabion retaining structure.This enhances the overall stability of the structure.(3)This article analyzes the dynamic response of the new gabion retaining structure under single boulder impact with the help of ANSYS/LS-DYNA finite element software,and explores the impact of changes in parameters such as boulder mass,boulder shape,boulder velocity,impact height,and headwater slope ratio parameters of the retaining structure.The results show that the peak impact force increases with the increase of boulder mass,boulder flatness,boulder velocity and headwater slope ratio,and decreases slightly with the increase of impact height.The boulder action time increases with the increase of boulder mass,and decreases with the increase of boulder flatness,boulder velocity and headwater slope ratio,but the impact action time does not change with the increase of impact height.The maximum values of support reaction force and displacement increase with the increase of boulder mass,boulder flatness,boulder velocity,impact height and headwater slope ratio.With the increase of boulder mass,boulder velocity and headwater slope ratio,the peak internal energy and final internal energy are increasing.As the boulder flatness increases,the peak internal energy decreases,while the final internal energy increases.However,the impact height has essentially no effect on the peak internal energy and the final internal energy.(4)As the single boulder impact the new gabion retaining structure is one-sided.Simplified analytical model to simulate 15 different sets of working conditions of the impacted new gabion retaining structure.To study the change law of dynamic response of the new gabion retaining structure under the impact of multiple boulders.The maximum value of the displacement at the extraction point occurs directly above the center of gravity of multiple boulders.The displacement of the same extraction point increases as the position of the center of gravity of the two boulders rises in different columns with the same height and in the same column with multiple points of impact.Under the different column and different height multi-point impact,it is determined that the impact position of the side column block is constant,and the displacement of the same extraction point increases as the height of the middle column block is raised.The kinetic energy conversion rate of the new gabion retaining structure is up to 65.5%,and its kinetic energy conversion rate is not greatly affected by different working conditions.The stress variation of the new gabion retaining structure under multiple boulder impacts is not much different.The stress is propagated in all directions with the point of impact as the center.Significant stress concentrations can occur locally and should be considered carefully in the future design.