| Earthquake-induced landslide is one of the most important secondary geological disasters in earthquake area,which poses great threat to people’s life and property security.With the implementation of the national medium and long term railway network project,the construction of several high-speed railway lines will be carried out in the mountainous areas with frequent earthquakes,so the seismic design of the slope along the railway has put forward a higher and more urgent demand.A thorough understanding of the dynamic response law of the slope under earthquake is helpful to better explore the internal instability mechanism of the slope under earthquake,so as to put forward a reasonable stability evaluation system,and at the same time provide a reasonable theoretical basis for the design and application of the slope support structure.The prestressed anchor cable,widely used in landslide control engineering in recent years,is a typical representative of the flexible support structure of the slope,and it can produce a certain amount of elastic deformation during the process of seismic action.However,when an earthquake occurs,the sliding body of the slope moves in a larger displacement,which is easy to cause the displacement of the anchor cable to be greater than its limit deformation value,then the cable body breaks and loses its supporting function.In this paper,FLAC3 D software is applied to explore the distribution form of the dynamic response of the slope without support under the action of earthquake.On this basis,a kind of prestressed anchor cable with double energy dissipation mechanism is proposed,which can cause the anchor cable to be greatly deformed in the earthquake process,so as to ensure the safety of the supporting structure and the slope,and its seismic performance is studied.The main conclusions are as follows:(1)Under the action of different types of seismic waves,the dynamic response of the slope has a similar law.The horizontal displacement of the slope surface increases gradually from the top to the bottom and reaches the maximum at the shear outlet of the slope foot.The vertical permanent displacement of the slope surface increases gradually from the toe up and reaches the maximum near the slope shoulder.The PGA amplification coefficient of slope points generally increases along the slope.The increase of amplitude of the loading waveform leads to an increasing trend of the slope body displacement and shear strain increment,the PGA amplification coefficient of the same position on the slope decreases,the damage degree of the soil around the danger monitoring point of the slope increases,and the seismic stability of the slope decreases.With the increase of soil cohesion and internal friction angle,the increment of slope displacement and shear strain decreases,while the yield frequency of soil decreases,and the seismic stability of slope increases.(2)A new type of energy-dissipating stress anchor cable supporting structure is put forward.The energy-dissipating anchor head has the dual energy-dissipating mechanism,which allows the controlled displacement of the landslide body,and can effectively prevent the anchor cable from being pulled,so as to achieve the purpose of seismic energy-dissipating and protecting the anchor cable.(3)Compared with the ordinary prestressed anchor cable supporting slope,the permanent displacement of the new anchor cable supporting slope is increased,but it is still in a relatively safe range,and it can be reduced by increasing the tensile yield load of anchor head element,which is suitable for the seismic needs of specific slope engineering.The increase of the slope displacement value in a safe and controllable range gives full play to the dissipation capacity of the slope to the seismic input energy.The axial force,the soil pressure under anchor head and the shear stress of grouting body in the anchorage section are generally less than that of the ordinary prestressed anchor cable. |
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