Dynamic compressive strength model for rock-steel fiber-reinforced concrete composite layer

In order to study the compressive strength model for rock-steel fiber-reinforced concrete (R-SFRC) composite layer under impact loading, the dynamic impact compression tests on the granite, concrete and R-SFRC composite layer are carried out by using the separated Hopkinson pressure bar to obtain the dynamic compressive strengths of different materials. With the regression fitting of the test results, three types of strength models for the R-SFRC composite layer called logarithmic, power function and strength-strain rate dependent mechanism are obtained, and the dynamic compressive strength models for the R-SFRC composite layer are established based on the Mohr-Coulomb strength criterion considering the interface interaction of the R-SFRC composite layer. The results show that the dynamic compressive strength of the R-SFRC composite layer increases with the increase of the strain rate and steel fiber content, and the range of the correlation coefficient of three regression models is 0.918~0.999, and the R² of the dependent mechanism model is the largest. The error range of the theoretical value of the dynamic compressive strength calculated based on the Mohr-Coulomb strength criterion relative to the test value is -9.23%~3.16%, and the maximum error value of the logarithmic model is the smallest. The computational model for the dynamic compressive strength of the R-SFRC composite layer can provide a theoretical basis for the design of the surrounding rock of concrete-supported tunnels.