Geometric optimization and jet-assisted efficiency enhancement of the dust collection inlet for tunnel construction-phase wet string grid dust removal vehicle

The dust hazard during drilling and blasting method construction significantly impacts the working environment and occupational safety of personnel. The wet string grid dust removal vehicle, as a novel tunnel dust control device, exhibits suboptimal dust control performance at its collection inlet, with great potential for improvement. Through theoretical analysis, numerical simulation, and experimental validation, the following results were obtained in this study: optimized the inlet structure to a parabolic type, with preferred geometric parameters of dimensionless diameter ratio 1.6 and dimensionless length ratio 0.4, after optimization, the pressure difference across the inlet decreased by 91.04 %, while the controlled length and disturbed volume increased by 25.03 % and 16.70 %, respectively; a jet-assisted dust collection inlet was proposed, with the critical momentum ratio determined as 0.219; when the jet velocity reached 20 m/s, the controlled length increased 2.59-fold; comparative analysis of post-blasting dust control effects revealed that the jet-assisted inlet effectively prevented dust diffusion to personnel-intensive zones, achieving a dust removal efficiency of 95.74 % at 10 m behind the vehicle. These findings provide theoretical support for optimizing dust collection inlet of the wet string grid dust removal vehicle and other dust removal equipment, as well as improving environmental conditions in construction tunnels.