【作者】 陈勇民；

【导师】 张土乔； 张仪萍； 邵卫云；

【作者基本信息】 浙江大学 ， 市政工程， 2011， 博士

【摘要】 承压式合流制溢流深井是在原有合流管道埋深较大时所采用的一种特殊的溢流井,这种溢流井在降低了造价和施工难度的同时也存在水力条件差和易于淤积的问题。本文采用现场探测、模型实验和数值模拟相结合的方法研究了承压式合流制溢流深井的水力特性和淤积规律,在此基础上设计了自虹吸水力清淤装置,并研究了该装置的水力特性和清淤效果。研究内容分述如下：1、应用管道声纳系统进行现场淤积调查,掌握承压式溢流深井的淤积状况和淤积变化情况；同时采用流量计监测流量变化,将其与淤积状况作对比分析。结果显示,溢流深井内普遍存在1-2m的淤积层,与B1型井相连的截流干管内基本没有淤积,而与B2型井相连的截流干管内存在0.1-0.4m的沉积层。2、通过模型实验和数值模拟研究承压式溢流井的水力特性和淤积规律,分析溢流井淤积原因,为设计清淤装置提供依据。结果显示,恒定流时溢流井内流场总体上呈现为包含两个螺旋上升涡流的对称结构,涡流中心的切应力和紊动能较小,泥沙实验时该区域的固体颗粒沉积量较大；涡流周边的切应力和紊动能较大,固体颗粒沉积量较小。3、根据承压式溢流井的水力条件,设计了自虹吸水力清淤装置。通过模型实验和数值模拟,研究了该装置的水力特性。结果显示,自虹吸水力清淤装置能明显改善溢流井底部的水力条件,其速度场对承压式溢流深井的清淤和防淤均能起到显著作用。自虹吸水力清淤装置运行所产生的井室底面切应力与作用水头差之间呈线性关系,而在相同水头差作用下底面切应力与虹吸管截面积参数(1/S)呈指数关系。4、通过泥沙实验研究了自虹吸水力清淤装置的清淤效果。结果表明：首次清淤率在总清淤率中所占比重最大,随着运行次数的增加泥沙面趋于稳定,清淤率急剧下降。首次清淤率和总清淤率均随着虹吸管截面积参数(1/S)值的增大而增大,但其增长速度随着(1/S)值的增大而降低,(1/S)增大到一定值后清淤率的增长不再明显。5、在固液两相流的数值模拟中,固体颗粒在边界的沉降现象与当地床面切应力(BSS)有较强的相关性,本文通过将遗传优化算法中的概率选择方法应用到判断颗粒物沉降的边界条件中,提出了“概率沉降”模型。该模型从沉降概率的角度描述固体颗粒与底面的碰撞行为,弥补了临界床面切应力模型不能区分不同区域颗粒沉降难易程度和预测相对沉积量的缺陷。将该模型应用于实验模型和实际溢流井淤积的数值模拟,模拟结果得到实验结果和声纳实测图像的验证。更多还原

【Abstract】 Pressurized combined sewer overflow(CSO) deep chamber is a special overflow chamber adopted in the interceptor sewer system where the buried depth of existing combined pipe is very large. This CSO chamber is adopted to decrease construction cost and difficulty while there are some problems such as worse hydraulic condition and sedimentation. The hydraulic characteristics and sedimentation regulation of pressurized CSO deep chamber were studied in this paper by combining field inspection, model experiment and numerical simulation. Moreover, based on the aforementioned study, a self-siphon sediment cleansing set was designed and its hydraulic characteristics was studied as well as cleansing effect. Detailed research contents are as following:1. In order to obtain the sedimentation conditions of the pressurized CSO deep chamber as well as sedimentation variation, pipe SONAR system was applied for field inspection. Meanwhile, flowmeters were applied to monitor the flow of CSO chamber which was used for the analysis with sedimentation condition. The results show that there are 1-2m thick sedimentation layer generally in the CSO chambers. There is commonly little sedimentation in the main interceptor pipe coterminous with B1-type chambers, while there are 0.1-0.4m thick sedimentation layer in the main interceptor pipe coterminous with B2-type chambers.2. The hydraulic characteristics and sedimentation regulation of pressurized CSO chamber were studied by model experiment and numerical simulation. And the sedimentation reason was analysed for the design of cleansing set. The results show that the flow field of chamber presents a symmetric structure including two spiral uprising eddies. The shear stress and turbulent energy are small at the central zone of eddy where sediment amount is large while the shear stress and turbulent energy are large at the circumjacent zone where sediment amount is small.3. A self-siphon sediment cleansing set was designed according to the hydraulic condition of the CSO chamber, and its hydraulic characteristic was researched by experiment and simulation. The results show that this sediment cleansing set can obviously improve the hydraulic conditon of the CSO chamber which is very beneficial to sediment cleansing and preventing. There is a linear relationship between the bed shear stress(BSS) of chamber bottom and the efficient water head of self-siphon sediment cleansing set, and a exponential relationship between the BSS and the siphon section parameter(1/S) under same efficient water head.4. The cleansing effect of self-siphon sediment cleansing set was investigated by sediment test. The results show that the first cleansing rate is the largest proportion in total cleansing rate. With the increase of operating number, the sediment surface tends to be stable and cleansing rate decreases rapidly. The first cleansing rate and total cleansing rate both increase with the increase of siphon section parameter(1/S), but its increase rate decreases with 1/S. When 1/S increases to a certain value, the cleansing rate do not increase obviously.5. In the numerical simulation of solid-liquid two-phase flow, there is strong relationship between particle settling phenomenon on boundary and local BSS. By applying the probability selection method of genetic algorithm to the boundary condition, the "probability sedimentation" model of particle was established. This model deals with collision behavior between particle and the bottom surface of chamber at viewpoint of settling probability, which makes up the defect of critical BSS model that the model can’t distinguish the settling difficulty degree and predict relative sedimentation amount. The "probability sedimentation" model was applied in the sedimentation simulation of model and actual CSO chamber, and the simulation results were validated by experiment and SONAR images of field measurement.更多还原