Numerical Modeling Of Collapsing Mechanism Of Roadbed Slope Under Rockfall Impact

With the advance of Western development, there is rapid development of highway construction in mountain areas in China. For the mountainous area road, rock fall hazardprone has become one of the main factors of roadbed landslide, seriously affecting traffic flow, even causing huge casualties. Combined design of Highway subgrade in rock fall impact theory and characteristics, using LS-DYNA explicit dynamic analysis based on finite element method, the main research is simulation of rockfall impact characteristics, different roadbed and pavement characteristics falling stone impact deformation of subgrade slope characteristics and mechanisms. Discusses the rock falls factors(such as the size of falling rocks, falling height and incident angle), subgrade structure factors(such as the sloping coefficients of bed rock and the artificial fill thickness) and pavement material(such as concrete and asphalt) on the impact effect of roadbed slope deformation and failure of rockfall. The main research work and results are as follows:(1)Obtained maximum impact force of rockfall by numerical simulation of rockfall drop test. Compared with the current impact of rockfall calculation methods, discussed the pros and cons of mainstream impact calculation method. And compared with the falling stone drop test data, verifies the feasibility of using LS-DYNA simulation of subgrade in rock fall impact.(2)Rock fall impact variables such as location, height, size, and angle of incidence. Make simulation of rockfall impacts mechanical response of dig-fill subgrade slope. Through the scope of impact and deformation and energy changes, results analysis, reveals the effect of characteristics on the impact of rockfall damage. Impact energy is the same as falling rocks on the surface deformation of subgrade degree of dimensional change impact, and height of subgrade deformation range and depth effects; impact location primarily to influence the failure location and scope of damage; incident angle is the main effect of deformation of surface layer of subgrade soil. The mechanism of subgrade slope sliding under different impact is summarized.(3)For half filling and half cut Rock Slope Subgrade Slope in different rate and filling thickness, simulation study in the same rockfall impact with different bedrock slope ratio and filling thickness of subgrade slope impact mechanical response of. The more slowly the bedrock slope is, the greater the energy dissipation of the roadbed side slope is. The filling is thick, rockfall prone to completely inelastic collision; filling thin, rockfall occurred completely inelastic collision trend. According to the specific route selection of highway geography and the humanities environment of subgrade slope rock rate and filling thickness, to improve the way of rockfall rebound. The influence of the change of digging and filling form on the mechanism of slope sliding is analyzed.(4)Simulation study of the low grade highway design commonly used three kinds of pavement materials(cement concrete, asphalt concrete and crushed gravel road surface) in the rockfall impact of subgrade slope deformation destruction of the impact. Found: impact resistance of cement concrete pavement best, but in rockfall impact fill surface of the airport has poor stability, resulting in close to the suspended pavement of airport surface and filling the bedrock interface stability is poor; asphalt concrete pavement and subgrade coordinated deformation and energy consumption performance optimal powder; and broken(gravel) stone pavement subgrade deformation is large, so it is difficult to protect embankment impact damage effect.