污水检查井盖调研及其预留孔对井内气体组分影响

Survey on Sewage Manhole Cover and Impact of Its Reserved Holes on Gas Components in Manhole

检查井盖预留小孔是污水管道与外界进行气体交换的重要通道。对比分析国内外关于检查井盖的相关规范及其在工程实践中的应用,虽然都规定在污水井盖上设置通气孔,但我国工程实践中几乎不在污水检查井盖上设置通气孔,而仅仅预留开启孔。对西安市污水检查井盖现状进行调查,发现井盖上的开启孔极易堵塞,堵塞率超过70%。对检查井内气体组分24 h的检测结果显示,开启孔虽然有一定的通气作用,但极为有限。将开启孔完全堵塞,断绝管道内、外气体的交换,对堵塞后井内的气体组分进行检测,发现管道内O_2不断被消耗,有害气体CH_4不断积累,最终对管道的安全运行和维护造成威胁。

The reserved holes of manhole cover are the important channel for gas exchange of sew- age pipeline with the outside. The domestic and international standards on the manhole cover and its ap- plication in engineering practice were compared and analyzed. It was found that both standards require that the vent should be set in sewage manhole cover, but the vent was almost not set in sewage manhole cover in engineering practice of China, only opening holes reserved. The survey on the status of sewage manhole covers in Xi＇ an found that the opening holes were easy to be blocked, with the blockage rate of over 70%. The 24-hour test results of the gas in the manhole showed that the opening holes had some ventilation effect, but it was very limited. The opening holes were completely blocked, and the channel of gas exchange was cut off to detect the gas components in the blocked manhole. The results showed that the 02 in the pipeline was consumed continuously, the harmful gas CH4 was accumulated continuously, which posed a threat to the safety operation and maintenance of pipelines.