## 1 Introduction  
In underground rock engineering and geohazard prevention and control, fissured sandstone, as a common rock type, has dynamic mechanical properties that are crucial to the assessment of engineering stability and geologic risk [1; 2]. However, in practical engineering, fissured sandstones are often subject to a variety of complex groundwater effects, which can result in large uncertainties in their dynamic response [3; 4]. Among them, strain rate is one of the key factors effecting rock response. Hence, the dynamic mechanical properties of water-saturated fissure rocks under various strain rates are of great importance for stability assessment and disaster prediction in deep rock engineering [5]. In past studies, many scholars have focused on the static and dynamic mechanical properties of fissure-bearing and water-bearing rocks. [PERSON] et al. [6] performed impact compression tests on seven groups of fissured sandstones of different dips using the Split Hopkinson Pressure Bar (SHPB) device (State Key Laboratory of Mining Response and Disaster Prevention and Control in Deep Coal Mines, Anhui, China). The results of the dynamic parameters of the specimens show that a 45\({}^{\circ}\) fissure angle is the optimal brittleness angle, and the differences in the damage patterns of the specimens are attributed to the presence of fissures with different dip angles. [PERSON] et al. [7] tested single-cleavage granite specimens under uniaxial compression and found that the rock mechanical parameters were highly correlated with fissure angle and temperature. [PERSON] et al. [8] studied the impact of crack length on sandstone's mechanical properties using the SHPB device under different impact air pressure conditions. The results of the study show that sandstone with the presence of fissures has an increased proportion of plastic deformation in the stress-strain curve. [PERSON] et al. [9] examined the mechanical properties of symmetric and asymmetric fissured rocks with static and dynamic loading at varying dynamic strain rates. The results indicate that the dynamic strength increases significantly with strain rate, whereas the dynamic modulus of elasticity is independent of strain rate. [PERSON] et al. [10] conducted dynamic impact experiments on rectangular marble specimens with cracks to investigate the impact of fissure angle and ligament angle on the dynamic mechanical characteristics and rupture behavior of rocks. [PERSON] et al. [11] performed triaxial compression experiments on specimens with monoclinic joints under different loading rates. It was concluded that the competition between mechanical damping and inertial forces led to the strain rate effect, and the peak strength of the specimens increased with the increase in loading rate. [PERSON] et al. [12] found that strain rate significantly affects the mechanics and rupture behavior of rocky specimens with two non-parallel fissures at different dip angles. [PERSON] et al. [13] examined the impact of preexisting defects with different angles and lengths on the dynamic mechanical properties of prismatic marble specimens with a single defect in the SHPB device. [PERSON] et al. [14], [PERSON] et al. [15], [PERSON] et al. [16], and [PERSON] et al. [17] explored the comprehensive effects of water and strain rate from dynamic compression experiments on both dry and water-saturated rocks for the mechanical properties and crack growth behavior of rocks. [PERSON] et al. [18] examined the impact of wet and dry cycles on the strength, damage pattern, and energy evolution of single-fracture carbonaceous shale. There is certainly a significant relationship between fissured rock energy dissipation and fragmentation patterns. [PERSON] et al. [19] conducted Brazilian disk experiments on four rocks at different strain rates using the SHPB device. Characteristic strain rates were applied to evaluate the extent of fragmentation and these were compared to existing theoretical tensile fragmentation models. [PERSON] et al.