Abstract:  In order to remove the dust produced by the tunnel drilling and blasting construction more quickly and effectively, three new dust removal technical schemes, i.e. auxiliary dust reduction water injection hole, differential water bag arrangement, and dust reduction water injection hole + differential water bag arrangement, are proposed, and field test is carried out on Jiaoding Tunnel. The test results obtained are as follows: the concentration distribution of dust, CO, CO2, O2 and NO2 in the longitudinal and transverse characteristic positions of the tunnel face area in the initial state, the variation rules of dust and CO concentration in the longitudinal characteristic positions with time under ventilation conditions, and the concentration distribution of dust and CO in the longitudinal and transverse characteristic test positions of the tunnel face area under three new hydraulic blasting schemes. Some conclusions are drawn as follows: (1) The concentration of dust and CO decreases fastest within 10 minutes of ventilation. (2) The dust reduction effect of the new scheme of hydraulic blasting is obvious, and the maximum dust reduction ratios of the three schemes are 36.84%, 40.85% and 65.74%, respectively. (3) The dust reduction water injection hole can play a good role in "sealing" the blasting dust. (4) The new scheme of hydraulic blasting can significantly reduce the CO concentration.

Key words: tunnel engineering, drilling and blasting method; hydraulic blasting, new dust removal technology, experimental research