Experimental study on seismic performance of composite reinforced structure with shock absorption and energy dissipation of potentially collapsedrock mass

At present, there are two types of structures for strengthening dangerous rock mass in earthquake area construction: anchorage and retaining. The connection between the two types of reinforced structures and the dangerous rock mass is rigid with very limited deformation ability between the structure and unstable rock mass, which leads to the poor seismic performance of the structure. Under the seismic load especially when the magnitude of earthquake is strong, it is easy to fail and cause collapse disaster. This kind of damage phenomenon exists in a large number of seismic projects in southwest China. To solve the existing problems of the reinforced structure, a composite reinforced structure was designed in this study, and it allows the dangerous rock mass to be dislocated to a limited extent under the action of earthquakes, can buffer the seismic impact force of the dangerous rock mass, and has the function of shock absorption and energy dissipation. The structure is composed of anchor rod (cable), shock absorber anchor head (primary energy dissipation), connecting beam, supporting pile, and a secondary shock absorber and energy dissipation device between the connecting beam and supporting pile. To verify the effectiveness of the composite reinforced structure, besides theoretical analysis, a physical model comparison test on the common anchor reinforced structure under the same conditions is carried out by using a shaking table. Different seismic waves, amplitudes and frequencies, which are representative of the region, are selected as input seismic loadings. Theoretical analysis and experimental results show that the displacement growth rate and cumulative displacement amplitude of the composite reinforced structure decrease significantly comparing to conditon for the same collapse body without protective measures. Compared with the traditional bolt-reinforced structure, the tensile force and pressure are significantly reduced. The amplification coefficient of peak acceleration PGA also decreased significantly. It is proved that the composite reinforced structure can effectively resist the dynamic stress caused by the earthquake on the dangerous rock mass by using its own elastoplastic deformation and damping force, effectively transfer the impact kinetic energy of the dangerous rock mass, and significantly reduce the shock and energy dissipation, which greatly avoids the damage of the reinforced structure and prevents the occurrence of collapse disasters. It is proved that the composite reinforced structure can slice off the peak seismic energy generated by small, medium and large earthquakes in layers, and has a good effect on damping and energy dissipation. This technology provides a new reinforcement scheme for the collapse dangerous rock mass, and has great practical significance for improving the consolidation technology of potentially collapsed rock mass in seismic area.