明渠流下生物作用对管道沉积物冲蚀特性影响试验研究

通过调节溶解氧环境和培养时间,采用循环水槽进行沉积物明渠流冲刷试验,研究生物活动对管道中不同有机物(volatile solid,VS)含量沉积物抗冲蚀特性的影响.结果表明:生物作用对沉积物抗侵蚀能力的影响具有两面性:一方面,生物作用促进沉积物颗粒间的结合力,另一方面,生物作用可通过增大沉积物内部结构的疏松程度以削弱其抗侵蚀能力.有机物含量较低的沉积物,存在一定生物作用,其抗侵蚀能力随培养时间而有所增强;反之,生物活动过于强烈,其抗侵蚀能力随培养时间而有所削弱.而对于适量VS含量的沉积物,生物作用对沉积物冲蚀的正负影响取决于水流剪切力的大小.

Flume Experimental Study of Erosion Characteristic of Sewer Sediment with Biological Activities

Seriousness of the problems caused by sediment deposits in urban sewer pipe has been widely recognized. Using circulating water tank, scouring tests on the sewer sediment with biological activities were carried out, and the influence of biological activities on erosion characteristics of real in-sewer sediment with different volatile solid (VS) contents under open channel flow by controlling the conditions of dissolved oxygen concentrations and incubation time was also investigated. The results indicate that the biological activities exhibited both positive and negative influences on the erosion law of sewer sediment. It improved the anti-erosion capability by enhancing the binding strength between particles, and the erosion resistance was weakened due to the increase of the porosity of the internal structure of the sediment. Meanwhile, the weak biological activities in the sediment with lower organic content can strengthen the erosion resistance with the incubation time. On the contrary, strong biological activities of sediment with high VS content leaded to the weakening of the erosion resistance. The effect of biological activities on erosion characteristic was also related to the shear force of the flow for the sediment with appropriate VS content.