地下空间氡的产生机理及通风控制

本文建立了土壤和建材的氡析出模型,在充分考虑各个影响因素的前提下,推导出了土壤和建材的表面析氡率公式,并依据此公式,进而推导出了室内氡浓度与通风换气效率的关系式。应用以上公式,对一典型的地下空间模型进行了计算,结果表明:地下空间氡的主要来源是土壤氡气的逸出,约占总析氡量的70豫～90豫;在较高的氡浓度状态下,室内氡浓度对通风十分敏感,增大地下空间的通风换气率,会使空气氡浓度大幅度的降低。因此,若按照地下空间的标准新风量进行设计,控制室内氡水平在400Bq/m3以内是很容易的,但是若要控制室内氡水平在200Bq/m3以内,则至少需要25.2m3/h的人均新风量,考虑新风不能得到完全利用,所需引入的室外新风量至少为31.5m3/h(以地下商场为例)。

Producing Mechanism and Ventilation Control of Radon in Underground Space

In this paper,the radon emanation model equations of soil and material are established.Considering each affected factor,the exterior emanation rate formula for the soil and building material were deduced,on the basis of which,the relation of indoor radon concentration and air change rate was deduced also.One typical underground space was calculated according to the formula obtained,and it was found that the main source of radon in underground space comes from the radon overflow in the soil which accounts for 70%~90% of the total radon emanation volume,and it was also found that indoor radon concentration is very sensitive to ventilation at the higher radon concentration.When increasing the air change rate in the underground space,the radon concentration in the air will fall fast.According to standards for the fresh air volume of underground space,the indoor radon concentration can be controlled under 400 Bq/m3easily.But when trying to control the indoor radon concentration under 200 Bq/m3,the fresh air volume per person must be above 25.2 m3/h.Considering that the fresh air can not be utilized completely,the outdoor air volume should be higher than 31.5 m3/h.