Dynamic Modeling And Analysis Of Coupling Between Rock Debris And Flexible Barrier Based On Explosion Simulation

Mountain is the main terrain of China,with frequent geological disasters,leading to a major threat to people’s lives and property.According to statistics,rock debris is the main form of actual rockfall.Among the existing protection methods,the flexible protective net has the advantages of quickness and flexibility,and is widely used in falling rock disasters.The European Guideline recommends the use of a single hammer equivalent to the natural rock debris,with the maximum impact deformation,the internal force peak of the component as the design basis and evaluation criteria,and the method is also directly adopted to national standards or technical guidelines.However,some researchers pointed out bullet effect on the flexible net,which means the higher overall cushioning performance of the system components and the local punching resistance of the ring net are requested.The system is uneconomical,even abandoned in design.Moreover,the equivalent method can not consider the inside effect of rock debris,the effect between rock debris and net,etc.,and it is difficult to reflect the real condition of flexible protective net.Based on this,this paper proposes a novel computational framework of an Air-Debris-Barrier(A-D-B)coupling model based on blasting simulation.Combined with full-scale impact test and numerical simulation,the dynamic responses of passive flexible protective system and hybrid flexible protective system under the impact of single block and rock debris are studied.The specific research contents and achievements are shown as follows:(1)The disadvantages of rigid body assumptions,discontinues deformation analysis(DDA),discrete elements method(DEM),smoothed particle hydrodynamics(SPH)were proposed.This paper established an Air-Debris-Barrier(A-D-B)coupling model based on blasting simulation,in which the rock debris are attained from an explosion based on Arbitrary Lagrangian-Eulerian(ALE)formula-based solid-fluid coupling,considering the factors of slip,contact and large deformation of flexible protection system.The A-D-B model can randomly generate the rock debris with impact kinetic energy.(2)Combined with 2000 kJ full-scale impact test of passive flexible protective net,thestructural mechanical behaviors under the impact of single block and rock debris are studied numerically.The research shows that the proposed method can effectively adapt to the whole impacting process,and effectively consider the load distribution and time lag effect of rock debris.For the passive flexible protection net model adopted in this paper,the impact peak force and deformation of the barrier decreased by 36.06% and 26.7%,respectively,and the internal peak force of the net reduced by 50% with respect to single block impact.(3)The numerical simulation of hybrid flexible protective net under the impact of single block and rock debris were carried out,and the mechanical behavior and energy consumption of system is studied.The results showed that,compare to the single block impact,the impacting force and the deformation of the system were reduced by 70% and20%,respectively,and the internal peak force of net reduced by 50% under the impact of rock debris.It should be noted that the system dissipation energy in the second stage was achieved about 42%,which was mainly induced by the friction dissipation.And the ratio of frictional energy in rock debris and total energy increased linearly with the friction coefficient.