Research on Control of Pollutants in Complex Underground Caverns Based on Required Air Volume Theory

The underground caverns has the advantages of safe concealment, environmental protection, and land saving. However, due to its enclosed space, pollutants are easily accumulated during construction. Consequently, improving the operation efficiency of the ventilation system and reducing energy consumption during the construction period are the keys to ensuring the safety of personnel and the normal operation of equipment. Taking an underground cavern project as the object, a theoretical calculation is used to determine the frequency conversion control strategy of the cavern fan, and numerical simulation (Fluent) is used to analyze the concentration changes of benzene and dust pollutants in the underground cavern before and after frequency conversion under the pressure ventilation condition, the field environmental quality monitoring data are compared and validated. The results show that: the concentration of pollutants on the longitudinal section of each cavern before and after continuous ventilation frequency conversion increases gradually and then stabilizes. The gradual conservation of pollutant generation and emission rates, with pollutant concentrations at breathing height below the limit values, verifies the effectiveness of the variable frequency strategy. In the construction site, the ventilation dynamic control system is established to realize the variable air volume control. When the axial flow fan maintains an energy-saving rate of around 25% and the jet fan maintains an energy-saving rate of over 60%, the pollutant concentration in the cavern remains within the limit range. This not only ensures the safety of construction personnel but also reduces energy consumption. The study can provide reference for the ventilation frequency conversion design of multi-face construction in underground caverns.