Research on Damping Shed Tunnel Based on SPH-FEM Coupled Algorithm and Model Test

In order to explore a more safe and effective slope rockfall protection structure, this study is based on the numerical calculation of SPH-FEM coupled dynamics and the 1∶10 geometric similarity indoor model test, aiming at the vibration reduction mechanism of the "sand-foamed rubber" composite cushion shed tunnel. The results show, when the falling rock is impacted at the speed of 20 m/s, the peak stress of the central unit of the roof abdomen can reach 2.89 MPa, which exceeds the ultimate tensile strength of C30 concrete by 2.01 MPa. After adding 0.2, 0.4, 0.6, 0.8, and 1.0 m foam rubber cushion, the peak stress of the central unit is 2.36, 1.12, 0.79, 0.65, and 0.58 MPa, which is 18.34%, 61.25%, 72.66%, 77.51%, and 79.93% lower than that of the pure sand cushion. Add 2, 4 and 6 cm thick rubber cushion at the longitudinal measuring point P1 on the roof belly of the shed during the test, and the peak strain is 50.57 με. It dropped to 27.17, 15.22 and 10.36 με respectively. The decrease was 46.27%, 69.90% and 79.51%. For the transverse test position T1 of the roof abdomen, the peak strain under the composite cushion condition is 48.47 με to 26.54, 17.29, 13.59 με. The composite cushion can significantly reduce the impact energy of rockfall and the stress level of the roof. The model test and numerical calculation results are basically consistent. The suitable thickness for on-site setting of foam rubber under this working condition is 0.4~0.6 m. The research results can provide reference and reference for relevant protective engineering design.