Study On Construction Ventilation Of Large Hydropower Station Underground Caverns

In the process of tunnel construction, such as drilling, blasting and slag, a large number of pollutants are produced. If the pollutants concentration exceeds the limited standards, a threat may be pose to the safety and health of workers. Ventilation is one of the most effective pollutants discharge method, the pollutant discharge effect may affect the quality of the working environment.In order to ensure the hydropower station underground caverns construction ventilation effect and creates a suitable environment for the construction, ensure the construction quality and construction safety, we need to make a study on the design of ventilation system, the fan layout and the operating and controlling scheme of ventilation system. On the other hand, hydropower station underground caverns is very complex which is composed of the water intake tunnel, the main powerhouse, the main transformer room, the tailrace surge tank, the tail water tunnel, the main electrical wire hall and many traffic tunnels underground caverns. All the tunnels are crisscrossed and concentrated, in the construction process, the construction link of mutual cooperation, mutual coordination and complicated, in the construction process, ventilation is not an easy problem to solve. Therefore, we need to make a special study on ventilation system.The research content is as follows:Firstly, four hydropower stations which are in different stages of construction are selected in this thesis. Through investigation and study, we have a sense of understanding the structure, construction technology and organization of hydropower station underground caverns as well as the investigation of ventilation system layout. The concentration of pollutants after the tunnel blasting and ventilation is tested. According to the structural characteristics of hydropower station underground caverns, and the construction schedule, the construction ventilation system numerical calculation model of hydropower station underground caverns is established, and verify the rationality and correctness of numerical calculation model.Secondly, in order to get the flow regularity of blasting fumes in the tunnel after blasting, this thesis do some analysis of the flow regularity of blasting fumes in the tunnel after blasting by using numerical simulation. A new amendment formula of pressed ventilation is put forward, on the basis of calculation results.Finally, this thesis makes a study on construction ventilation system of hydropower station underground caverns. The construction ventilation system of Baihetan hydropower station underground caverns is simulated to investigate the influence among each ventilation area, the ventilation effect of different fan’s position. A reasonable layout scheme of fans and the fan control scheme for different construction conditions are put forward.