Study On The Mechanical Properties And Energy Dissipation Capacity Of Metal Flexible Net In Passive Flexible Protection

China is a mountainous country.Most of the mountainous areas have complex geological structures,steep terrain,and severe fracture of surface rock mass.It is easy to cause geological disasters such as collapse and falling rocks and mudslides,resulting in a large number of loss of property.There are a variety of protection measures,among which the passive flexible protection is widely used in practical engineering due to its light structure,simple construction,standardized production,economy and environmental protection,and strong adaptability.The metal flexible net is the main energy-consuming component in the passive flexible protection,but in the actual engineering,the phenomenon that the metal flexible net breaks frequently occurs.Therefore,the mechanical properties and energy consumption characteristics of metal flexible nets are studied,which provides a reference for the design and selection of metal flexible nets.In this paper,the energy dissipation performance of diamond net and ring net commonly used in engineering is studied.The main findings are as follows:(1)When the falling rock shape is a cube,the diamond net is more likely to be destroyed.In the full-scale test,using polyhedron to simulate falling rock can more accurately reflect the situation of falling rock impact diamond net in actual engineering.The use of spheres to simulate rockfall in numerical simulation is beneficial for finite element analysis.(2)When the mesh is short diamond,the net consumes the most energy,and when the mesh is rhomboid,the horizontal displacement of the upper support rope is the smallest.The diamond-shaped net of the rhomboid mesh is more conducive to the secondary protection of the falling rock.Therefore,in the actual project,the selection of diamond net should be carried out according to the actual situation of falling rock.The diamond net with short diamond mesh should be selected when the maximum energy consumption is considered,and the diamond net with long rhomboid mesh should be selected when the secondary protection of rockfall is considered.(3)When using the same material dosage,the energy consumption of the 1-6 ring net is much larger than that of the 1-4 ring net,but the maximum horizontal displacement of the support rope on the 1-4 ring net is less than 1-6 ring net,therefore,the 1-4 ring net is more conducive to the secondary protection of the ring network.(4)Regardless of the diamond net or the ring net,the maximum vertical displacement of the net,the maximum horizontal displacement of the support rope and the maximum energy consumption are larger than considering initial deformation when the initial deformation is not considered.Therefore,it is suggested to consider the effect of initial deformation when analyzing the energy dissipation and mechanical properties of the large-span passive flexible protection.