【作者】 马妍；

【导师】 邵卫云； 周永潮；

【作者基本信息】 浙江大学 ， 建筑与土木工程（专业学位）， 2014， 硕士

【摘要】 排水系统是一个城市重要的基础设施,在长期的运行过程中,管道内极易发生沉积物淤积现象。本文在总结前人关于排水系统管内沉积物的构成、污染及运动特性等方面研究的基础上,采用现场调查和模型试验相结合的方法,对不同程度生物作用下管道沉积物的冲蚀输移规律与特性进行研究。主要研究内容如下：(1)以浙江省嘉兴市不同区域排水系统为研究对象,对不同排水体制下的管道沉积物的多项物理特性指标展开调查研究。结果显示,相对于分流制雨水管道沉积物,合流制管道沉积物具有较高的挥发性有机物含量及较小的颗粒粒径,表现出更强的有机特性。(2)以真实的排水管道沉积物为试验对象,在实验室内进行培养,通过温度、溶解氧、培养时间等环境条件的调整来控制沉积物中的微生物作用强度,探讨不同程度生物作用下沉积物结构松散程度及抗侵蚀性的变化规律。结果显示,较高温度和充足的氧气供应相对于低温和厌氧条件更能促进生物作用,此外,生物作用对沉积物特性的影响效果还取决于沉积物内部的挥发性有机物含量。含量较低时生物作用不明显,沉积物表现出无机颗粒特性；含量过高则导致生物作用加剧沉积物内部结构的松散程度,使其抵抗侵蚀的能力得到削弱。(3)以不同挥发性有机物含量的真实管道沉积物为试验对象,研究了生物作用程度不同的沉积物在恒定流水力条件下的侵蚀率动态变化规律。结果表明,生物作用程度存在差异,导致沉积物的抗侵蚀能力随培养时间的变化规律也明显不同：有机质含量较高(16.01%)的沉积物抗侵蚀能力随培养时间不断减弱；含量较低(5.12%)的沉积物抗侵蚀能力随培养时间有所增强；含量为10.96%的沉积物抗侵蚀能力变化规律还与剪切力因素相关,剪切力较小(τ=0.21N/m2～0.58N/m2)时,抗侵蚀能力随培养时间增强,剪切力较大(τ=0.64N/m2～0.73N/m2)时,抗侵蚀能力随培养时间不断减弱。(4)考虑工程实际中排水系统内水力条件的间歇变化性,利用室内管道装置,分析不同工况下的瞬时大流量冲刷对高有机性管道沉积物冲蚀输移规律的影响,并与无机性天然河沙进行对比研究。结果表明,高有机性导致管道沉积物在生物作用下颗粒间粘聚力较大,在冲刷过程中多以颗粒团的形式运动,另一方面,由于颗粒间粘性的存在,沉积物冲蚀总量受床面剪切力的影响较冲刷历时的影响更加明显。更多还原

【Abstract】 Sewerage system is one of the most critical infrastructures in a city. However, in the long-term working process, sewer sediment is prone to appear in drainage pipelines due to unreasonable design, or imperfect operation management, etc. Since the existing research on erosion characteristics and transport principles of sewer sediment is insufficient, this paper uses the method of combining on-site investigation and model test to study the erosion characteristics and transport principles of sewer sediment. The main contents are as follows:(1) Jiaxing, in Zhejiang Province has been used as the demonstration areas to study apparent characteristics, particle size distributions, content of volatile organic compounds and other indicators of sewer sediment under the conditions of both separated drainage system and combined sewer system. The result shows that, compared with separated drainage, sediment of combined sewer system shows organic characteristics more obviously, which contains a higher content of volatile solid and smaller diameter.(2) Real sewer sediment has been used as experimental subject to explore the sediment structure and anti-erosion variation with different levels of biological action by adjusting the temperature, dissolved oxygen, training time and other environmental conditions to control the strength of microorganisms in sediments in the laboratory. The result shows that, compared with lower temperature and anaerobic conditions, higher temperature with adequate oxygen supply promotes biological effects. In addition, the influence of biological effects on sediment characteristics depends on volatile organic content of the sediment inside as well. When contents are lower, biological effects are not obvious, and sewer sediments showed inorganic particle properties. On the contrary, when contents are higher, biological effects intensified the loose degree of the internal structure of sewer sediments, and finally weaken the ability to resist erosion. (3) Real sewer sediments with different volatile organic contents have been used as experimental subjects to study the dynamic erosion rule of sediment samples under the step change in steady flow with different levels of biological effects conditions. The result shows that variations of anti-erosion ability of sediment with different volatile solid content during the experiment are disparate. For sewer sediment with high content of VS(16.01%), anti-erosion ability has been weakened during the experiment. For sewer sediment with low content of VS(5.12%), a strengthen of anti-erosion ability has been observed during the experiment. For sewer sediment with VS content of10.96%, variation of anti-erosion ability is related to shear force, anti-erosion ability is strengthen under weaker shear force of0.21N/m2～0.58N/m2, while anti-erosion ability is weaken under weaker shear force of0.64N/m2～0.73N/m2.(4) In consideration of intermittent flow in sewer system, pipe model is used to analysis erosion characteristics and transport principles of sewer sediment with high VS content under erosion of instantaneous flow. The result shows that cohesion of sewer sediment has been enhanced during biological process, as a result, sewer sediment is transported in a form of particle group while being flushing. On the other hand, the influence of shear force on erosion rate is much more obvious than that of flushing duration because of the cohesive characteristics.更多还原