Dynamic mechanical response and damage constitutive model of end-jointed rock bridge with different water content states under impact load

In rock slope engineering, the dynamic mechanical behavior of rocks is significantly influenced by the length of rock bridges and their moisture content. This study explored the dynamic characteristics of defective rocks under impact loads through dynamic impact tests on specimens varying in rock bridge lengths and moisture states, conducted using a Split Hopkinson Pressure Bar (SHPB). The experimental results revealed that both moisture state and rock bridge length markedly affect the dynamic compressive strength and elastic modulus. Additionally, there is a significant correlation between the energy dissipation density and the specimen's moisture state and rock bridge length. The failure process, captured via a high-speed camera, exhibited a transition in fracture mode from predominantly tensile to tensile-shear failure with increasing rock bridge length. Moreover, an enhanced ZWT model was developed and validated for the dynamic damage constitutive model of defective rocks. This model, incorporating four parameters, precisely characterizes the stress–strain relationship of defective rocks under high strain rates and effectively demonstrates the dynamic response of rocks with varying rock bridge lengths and moisture states. The findings of this study are vital for advancing the understanding of rock dynamics in varying conditions and offer significant insights for geological and civil engineering applications, particularly in the design and assessment of rock structure stability in slopes.