Pre-splitting Blasting Technology for Tooth Groove Slopes in Sandstone Mudstone Interlayer of Laomukong Navigation Hydropower Hub

Pre-split blasting serves as a critical technology in control blasting operations, with its superior formation quality contributing significantly to construction safety and project economic efficiency. To optimize pre-splitting blasting performance for tooth groove slopes within the sandstone-mudstone interlayer at Laomukong Navigation Hydropower Hub, this study integrates geological surveys, rock mechanics testing data, and theoretical analysis of blasting mechanisms. The research systematically develops comprehensive blasting plans with detailed parameters, while introducing customized linear charge density design methodology for individual blast holes adapted to complex geological environments. Quality control protocols were established for drilling operations, charging procedures, and stemming processes to guarantee blasting quality, involving the development of drill pipe positioning devices, precise charge control measures, and innovative stemming material formulations. Finite element numerical simulation of pre-splitting blasting was conducted using the dynamic analysis software ANSYS/LS-DYNA, complemented by field blasting tests to validate the rationality of parameter design and construction methodology. Simulation results demonstrate that the designed parameters enable effective superposition of stress waves between adjacent blastholes during tooth-groove slope blasting, thereby achieving optimal fracture propagation while maintaining intact rock conditions in preserved zones with minimal damage. Field test results demonstrate that meticulous blasting parameter design and rigorous construction quality control achieved exceptional pre-splitting performance for the tooth-groove slopes at Laomukong Navigation Hydropower Hub, with average half-hole preservation exceeding 90% and surface flatness maintained at 6.5 cm. This optimized blasting effect effectively mitigated vibration impacts, maintaining all monitoring points′ vibration velocities and dominant frequencies within established safety limits. The concrete left guide wall exhibits a maximum vibration velocity of merely 1.10 cm/s, significantly below the safety threshold of 3.5 cm/s. Its vibration frequency exceeds 10 Hz, surpassing typical structural natural frequencies (1~10 Hz). These findings validate the rationality of the initial blasting scheme and establish technical references for pre-splitting blasting projects under analogous complex geological slope conditions.