Research on the Dynamic Mechanical Properties of Rock Mass Strengthened by Grouting Under the Action of Salt Solution Corrosion

In the development of deep offshore mineral resources and underground engineering projects, the engineering rock masses are continuously exposed to high-salt groundwater infiltration and chemical corrosion, resulting in significant deterioration of their mechanical properties, especially the response characteristics under dynamic loads, which seriously affects the stability of the surrounding rock. Existing studies have mostly focused on the static corrosion behavior of intact rocks, while paying insufficient attention to the dynamic mechanical performance evolution laws of rock masses reinforced by fissure grouting in the engineering field. This paper takes the grouted granite rock mass as the research object, simulates the deep groundwater environment by preparing different concentrations of composite salt solutions, and conducts periodic immersion corrosion treatment on the rock samples with pre-set fissures and grouting. Using the separated Hopkinson pressure bar system, dynamic impact tests are carried out on the samples before and after corrosion. The influence laws of salt solution concentration and corrosion cycle on the dynamic tensile strength, failure mode and energy dissipation characteristics of the grouted reinforced rock mass are systematically analyzed. The results show that after being corroded by the salt solution, the peak stress drop rate of the test samples' dynamic stress-strain curve slows down, and the residual stress platform becomes more obvious. Within 30 days of corrosion, the low concentration group such as the 5% mass fraction salt solution group shows a temporary increase in the dynamic tensile strength of the test sample due to the filling of pores by corrosion products, with the maximum value reaching 31.5 MPa. However, as the concentration and time increase, the strength shows an overall downward trend. Energy analysis shows that the proportion of the absorbed energy after corrosion of the test sample decreases, and the reflected energy dominates. The absorbed energy shows a non-monotonic change of first decreasing and then increasing with the increase of solution concentration, and reaches a minimum value of approximately 22.3% at a concentration of 10%. This study reveals the complex influence mechanism of water chemical corrosion on the dynamic performance of grouted reinforced rock masses, providing an important reference for evaluating the dynamic stability of rock mass engineering under corrosive environments.