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采用美国联邦公路管理局提出的偏沟和雨水口流量计算方法,经计算发现我国《雨水口》(16S518)标准图集中雨水口泄水能力推荐值有不合理之处。通过分析国内外道路坡度和雨水口布置的相关要求,结合案例计算,总结了道路横坡、纵坡、箅前水深和雨水口布置间距之间的变化关系,并提出道路设计漫幅的推荐值。通过调整道路设计坡度,将道路路面转变为兼具收集和输送路面雨水功能的路面行泄通道,并利用曼宁公式计算了路面行泄通道的排水能力。 相似文献
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根据小流域暴雨产流过程与城市雨水道的特点,分析现行综合径流系数法应用上的缺陷,提出径流造峰条件与洪峰径流系数法的计算公式。对于汇水面积较大、集流时间较长的沟段有削减设计流量的重要意义。认为当前应用的数学模型法用于城市雨水道设计值得商榷,应了解基本原理和参数确定,不能盲目套用。 相似文献
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以重庆市渝北区和巴南区的典型下垫面为研究对象,基于SCS-CN模型原理和坡度修正公式,通过开展人工模拟降雨实验,优化了不同植被覆盖程度的紫色土和黄壤下垫面在不同坡度(5°、10°、15°和20°)下的CN值,同时采用模型评价参数对优化前后的模型预测精度进行对比。结果表明:地形坡度变化对径流深有显著影响,地表径流深随坡度的增大大体呈现增加的趋势。同一类型下垫面的CN值随坡度的增大而增大,同一坡度下的CN值存在黄壤>紫色土,自然草地(稀疏)>自然草地(浓稠)。从模型评价参数来看,由Huang坡度修正公式修正后的模型效率系数最高且平均相对误差最小。因此,在山地城市应用SCS-CN模型时,建议使用Huang坡度修正公式对CN值进行优化,以便更精准地预测径流。 相似文献
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作为城市面源污染的重要组成部分,初期降雨径流污染处理不当,会严重污染区域内地表及地下水水质,因此对不同暴雨强度下初期雨水截流特征的模拟分析具有重要意义。利用SWMM 5.0软件,对研究区域内初期雨水截流效率特征进行模拟,分析不同暴雨强度及特定截流方式下的初期雨水截流特征演化。结果表明:(1)本研究范围内,随着重现期增加,暴雨强度会逐渐增大,并在降雨末期趋于缓和。(2)降雨重现期对雨型的影响较弱。(3)本研究范围内,随着暴雨强度的提高,采用末端截流方式下的初期雨水截流效率会降低。研究结果可为市政工程规划中不同暴雨强度下的初期雨水截流工艺的选定提供理论指导。 相似文献
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The paper attempts to explain sources of surplus storm water runoff in urban areas, particularly in relation with functioning of inlets. Inlet capacity (quantity of captured water) and inlet efficiency (portion of the approaching flow rate) have been defined and their relationship with relevant parameters (approaching flow, longitudinal and lateral street slopes) was established through laboratory measurements. Effects of clogging of inlets on inlet capacity were also investigated in laboratory conditions. As a consequence of decreased inlet efficiency, there is a portion of approaching flow that is not captured by the inlet (pass-over flow). If the pass-over flow is considered along a street having numerous inlets, it is easy to estimate the quantity of flow that would accumulate on the pavement. Inlet inefficiency can be significant when overestimation of inlet capacity results in increased distance between consecutive inlets, and when clogging of grates or inadequate placing of inlets causes significant decrease in inlet capacity. 相似文献
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An Approximately Semi-Analytical Model for Describing Surface Runoff of Rainwater Over Sloped Land 总被引:1,自引:0,他引:1
Ting Yang Quanjiu Wang Lijun Su Laosheng Wu Guangxu Zhao Yanli Liu Pengyu Zhang 《Water Resources Management》2016,30(11):3935-3948
Accurate prediction of surface runoff is critical to watershed management. In this research a semi-analytical model was adopted to solve the kinematic wave equation based on the assumption that the rate of overland-flow depth change is proportional to the rainfall excess. Simulations were compared with the results from laboratory experiments at various rain intensities. Parameters of infiltration rate and Manning’s roughness coefficient were determined. The accuracy of the semi-analytical model was evaluated by numerical simulations. The predicted outflow rates from the numerical simulations agreed well with the observed data. Further, our study indicated that the ratio (c) of the overland-flow depth change to the rainfall excess was a power function of the rain intensity. The depth and velocity of water flow at any time and distance could be calculated with the semi-analytical model. Hydraulic parameters including Reynolds number, Froude number, hydraulic shear stress, stream power and Darcy-Weisbach friction factor characterizing the dynamic features of overland flow of rainwater were calculated based on calculated overland-flow depth and velocity. The proposed analytical method can provide a new way to predict infiltration and runoff over sloped land. 相似文献
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针对西淝河闸站工程在闸、站单独运行时存在的回旋和斜流问题,采用整体正态模型对闸站工程进行水工模型试验研究。在抽排水工况下,设计了不同导流墩长度,不同导流墩开孔尺寸包括开孔宽度、开孔间距、开孔高度等7种导流墩整流方案;其中对仅25 m长导流墩方案和导流墩最优开孔尺寸方案进行了自排工况下自排闸的过流流态及流速分布研究。通过对比各方案下导流墩侧回旋区面积大小及各孔流速均匀度,建议导流墩长25 m,开孔宽4.5 m,相邻的孔口间距6.25 m,开孔高度5 m。5#和6#流道中间加设1 m短隔墩的方案可减小泵站前池及闸前水流回旋区域,改善水流流态,提高各孔流速均匀度,为泵站机组及水闸运行提供良好的水力条件。试验研究结果可为闸站结合工程选择导流墩整流方案提供技术参考。 相似文献
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基于热示踪的饱和层状介质水热参数反演 总被引:3,自引:0,他引:3
多孔介质的水热运移参数是影响介质中水热运动过程的主要因素。本文基于热示踪方法,开展了稳定流场条件下饱和层状石英砂的热示踪实验,分别采用热电偶与热成像两种方法测定了砂箱内部和表面的温度,同时结合HYDRUS模型的反问题算法对层状石英砂的水热运移参数进行了反演。研究结果表明:当介质中存在细粒夹层时,热成像图像能反映非均匀流场中热流峰面在分层界面处出现的"收束"现象;层状介质中的细颗粒夹层可导致热流锋面沿水流方向迁移速率下降、热量沿垂直于水流方向运移范围加大、温度分布更均匀。同时对于热源持续输入的系统,热成像温度在前期能较好的反映层状介质对水流运动的影响。将热示踪与HYDRUS模型相结合可较好地用于反演介质水热运移参数,反演所得的饱和导水率估值随粒径的减小显著降低,纵向热弥散度随粒径的减小而增大,而横向热弥散度变化趋势与之相反;纵横弥散比变化范围在10~120之间,且纵横弥散比随粒径减小而逐渐增大。对细砂饱和导水率的估计不足及热量损失是造成水流通量估计误差的主要原因,在模拟模型中增加细砂层测点数量可显著降低水流通量的估计误差。本研究可为非均质介质中水热迁移过程模拟与参数反演提供相应的方法。 相似文献
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EXPERIMENT OF IMPACT OF RIVER HYDRAULIC CHARACTERISTICS ON NUTRIENTS PURIFICATION COEFFICIENT 总被引:3,自引:0,他引:3
WANG Pei-fang WANG Xiao-rong WANG Chao 《水动力学研究与进展(B辑)》2007,19(3):387-393
Hydraulic characteristics of a river are the key factors for river water quality improvement and river restoration. A simulated river was exploited to study the interactions between water contaminant purification coefficients and the characteristics of the river, such as the cross-section velocity, water depth, Reynolds number, and Froude number. To enhance the purification capacity of the river, detritus with 5 mm to 10 mm in diameter and contact surface area per volume of 87.6 m2/m3 were constructed naturally at the bed and along one side of the bank to form half shape of the river cross-section. During the one-month experiment (including 3 periods) from the third of November to the fourth of December, 2005, three categories of hydraulic conditions were investigated. Results show that the purification coefficient (K) of Total Nitrogen (TN) is closely coherent with the hydraulic retention time (T), river length (L), Reynolds number (Re) and Froude number (Fr). The relationship of K and T generally agrees with the power law under the three experimental water hydraulic conditions. Based on these results, the optimal Re and Fr ranges can be obtain to serve as a guideline for ecological re-engineering design to improve river water quality and restore river ecosystem. 相似文献
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台阶式溢洪道是目前研究的热点,台阶消能率和佛汝德数是重要的水力参数。将台阶式溢洪道佛汝德数与对应光滑溢洪道佛汝德数对比,引入相对佛汝德数的概念,准确地反映由于台阶的存在对水流佛汝德数的改变值。通过对0.5,1.0,2.0 m 这3个不同台阶高度,坡度为38.66°的台阶式溢洪道进行试验研究,探讨了相对佛汝德数和相对消能率之间的关系。结果表明非均匀流流态下相对佛汝德数和相对消能率表现出良好线性关系,相关系数为0.992 7~0.998 9。单宽流量不同,相对佛汝德数和相对消能率对应直线的斜率明显不同,其斜率随单宽流量加大而增大;而台阶高度变化对相对佛汝德数和相对消能率线性关系的直线斜率影响很小。 相似文献
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晋西黄绵土坡面径流流态与输沙特征试验研究 总被引:1,自引:0,他引:1
为了探讨晋西黄绵土坡面径流流态与输沙特征,本研究采用室内人工模拟降雨试验方法,对降雨条件下坡长对该区坡面径流雷诺数、弗劳德数、径流量、产沙量与输沙率进行量测与分析。结果表明:在雨强30~125mm/h、坡长1~5m的情况下,坡面薄层径流为层流,且为急流;径流流态对坡面水流侵蚀力有显著影响,产沙量与雷诺数呈良好幂函数关系;雨强与坡长的增大可增强径流紊动性,输沙率随二者的增大呈增加趋势,当雨强大于60 mm/h、坡长由3 m延长到4 m时,输沙率增量较2~3 m与4~5 m时小;输沙率与径流量的关系可用幂函数描述。该研究结论能够为黄土陡坡面水土流失治理和水土保持措施的布设提供一定的依据。 相似文献