Study On Technology Of Surfactants Dust Suppression In Tunnel Water-Pressure Blasting

Large amounts of rock dusts are produced in the tunnel blasting, the operator would be injured and the environment would be polluted by these high concentration dusts. The technology of water-pressure blasting has been widely used in tunnel engineering, which is an effective measure to improve the blasting effect and control dust concentration, in some extent. However, the surface tension of water is large and its wettability is low in the dust. The practical application effect is not helpful. Using surfactants to reduce dust concentration has largely adopted in the mining dust control technology, but fewer applied in the tunnel.Based on the theoretical study, laboratory experiment and field application, the theory of water-pressure blasting and surfactants influence in improving water mist, wettability enhancement and the dust concentration control has studied systematically. In this paper, based on the surface tension and wettability, three kinds of six different surfactant solutions were selected to test the surface tension for the study of surfactant monomer effect and experimental scheme to compound. Three different rock samples were collected to test the contact angle, and the result showed that the contact angle was lower than the water, both in the range of wetting and partially wetting and the wettability had large difference among different rock. So both surface tension and contact angle should be taken into account in tunnel surfactants chosen. Based on the principle of surfactants compound, six kinds of surfactants have been compounded in their CMC concentrations, then compared the dust-control effect. In this paper, surfactant formula T7 prepared by the anionic surfactant and zwitterion surfactant was proposed for its low surface tension and good wettability.Field application showed that influence by the operation such as ventilation and slag transport, there are many dust concentration test influencing factor. So the practical operate condition should take into account in the inspection of dust control effect. Combined with the technology of water pressure blasting, surfactant formula was added to the blocking water bag and put this method into the practical tunnel engineering. The evaluation scheme is comprehensive which included real-time concentration determination of the blasting safety distance, concentration distribution determination of cross section and dust concentration determination limited in 30 m of tunnel face. LD-5 laser dust meter was used in measuring the different concentration variation between the traditional method and the added surfactant formula method of the water blasting. The result showed that compared with the tradition method, the concentration of PM2.5 was reduced adopted the surfactant. Therefore, adding T7 surfactant formulation can reduce the dust concentration of tunnel blasting and reduce the probability of occupational disease.