## 1 Introduction
[20] studied the mechanical properties, damage behavior, energy dissipation characteristics, and damage mechanisms of fissured rock specimens with different prefabricated fissure angles. [PERSON] et al. [21] carried out triaxial dynamic tests on sandstone containing prefabricated cracks at different strain rates and concluded that the dynamic strength and energy dissipation density of sandstones increased with increasing strain rate. [PERSON] et al. [22] investigated the increase in strain rate under dynamic uniaxial compression leading to an increase in fissure surface area and specific fracture energy during rock fragmentation. By translating into engineering dimensional parameters, this can be used to optimize rock destruction and reduce ore loss and energy wastage. [PERSON] et al. [23] studied the characteristics of fluid transport properties and permeability evolution in heat-treated rock samples containing single fractures. After high-temperature exposure, the roughness of the fracture surface increased, and the fracture flow was affected by the temperature and surrounding pressure. [PERSON] et al. [24] researched the effect of strain rate on the dynamic response of fractured rock using high-speed loading. The results show that an increase in strain rate leads to increased rupture, increased energy dissipation density, and the insignificant effect of crack strength on some properties. [PERSON] et al. [25] tested dynamic impacts on rocks with different bridge lengths and water contents and found that the moisture status and bridge length significantly affected the dynamic compressive strength, elastic modulus, and energy dissipation density. It should be noted that there are fewer studies concerning the dynamic mechanical properties of water-saturated fissured sandstones under different strain rates; studies are mostly focused on intact rock specimens under static loading conditions. Further exploration is necessary to fully understand the effects of fissure-containing and water saturated conditions. Therefore, in this paper, the SHPB device was used to conduct dynamic impact compression tests on prefabricated fractured 45\({}^{\circ}\) dip angle water-saturated sandstone specimens using different air pressures to analyze the effects of strain rate on the dynamic mechanical properties, crushing patterns, and energy dissipation. The results of this study indicated that water-saturated fissured sandstone fragmentation is more obvious at high strain rates, and these findings are helpful for specific areas of rock engineering involving high strain rates, such as mine blasting, underground tunneling and geotechnical engineering, dam and levee design, and military protective structures. For mine and mining engineering, the cracking behavior of rocks directly affects blast design, risk of rock failure, and mining efficiency. For dams and hydraulic engineering, understanding the mechanical properties of rocks under different strain rates can guide the design and maintenance of dam structures. The increase in rock strength under dynamic loading is a factor that influences the design of underground protective structures and the placement of blast holes. By analyzing the response mechanisms of water-saturated fissured sandstones under dynamic loading, we can better predict and respond to the complex engineering geological problems that may be encountered in underground projects, thus enhancing the overall performance and sustainability of underground projects.