Abstract: To address the low efficiency of conventional grouting methods in controlling sudden water inrush in deep excavations, this study developed a novel composite slurry. The base slurry consisted of cement-sodium silicate, modified with 1.5% polyacrylamide(PAM)and 1.0% sisal fiber(SH). A three-dimensional blocking and filtration system was constructed by integrating natural loofah skeletons(porosity ≈ 80%)with uniformly graded sand and gravel(1~7 mm, with equal proportions of each fraction). Laboratory tests demonstrated that the composite slurry increased retention by 44.83% compared to the original cement-sodium silicate slurry and maintained excellent sealing performance under flow velocities ranging from 0.2 to 0.6 m·s^-1. The three-dimensional network significantly reduced flow velocity, achieving a maximum reduction of 37.5%, and ensured over 80% soil retention even at 0.6 m·s^-1. These results indicate that the synergy between the modified slurry and the structural filtering system not only improves erosion resistance but also enhances consolidation and energy dissipation performance.