城市供水管网系统抗震功能可靠性分析

城市供水管网系统是生命线工程系统的重要组成部分,一旦其遭受地震作用,可能损坏严重并产生各种次生灾害。以湖北省武汉市青山区主干供水管网系统为例,根据供水功能要求,对震前和震后的供水管网进行了水力分析,通过连续性方程、能量守恒方程和物理方程推导得出了水力方程的解析表达式,并通过迭代法求解得到了供水管网的水力参数;通过可靠度理论,分析了供水管网系统节点的供水可靠概率;计算了在不同地震水准下的供水功能可靠性,证明了该分析方法的合理性、可行性。     

基于GIRAFFE模拟的震后供水管网优化恢复过程研究

为提升供水管网震后快速恢复效率,提出了基于GIRAFFE模拟的震后供水管网优化恢复方法。针对震后供水管网破坏节点负压影响,采用以EPANET内核为运算引擎的GIRAFFE进行供水管网系统地震破坏模拟分析,得到供水管网震后损失水力参数;以此为基础采用两阶段恢复策略进行了修复优化,即第一阶段以管网供水满意度提升最大为目标,以各个破坏管道修复后的供水满意度为依据进行破坏管道修复,第二阶段通过对损伤管道动态修复的水力参数适时计算,以减少管网漏水为目标进行破坏管道修复。同时,考虑供水管网震后大面积破坏特征,建立了维修队伍指派优化模型。最后,通过某城市管网案例计算分析研究,给出了供水管网优化恢复方案,为综合保障震后居民用水需求提供了技术支撑。     

城镇供水管网瞬变流计算

为防止复杂供水管网出现有害水锤，需通过瞬变流数值计算来预测系统内由升压水泵的启停及管网内某些阀门的开闭所引起的压力波动，这些压力波动有时会引起爆管、震裂阀门等恶性事故。利用由特征线法建立的供水管网瞬变流计算数学模型，可预测管网运行中出现的有害水锤，并求得可能出现的最高（最低）压力，为设计者采取防护措施提供理论依据。     

基于EPANET和ArcObjects的在线水力模型系统开发

目前自来水公司普遍存在技术水平和管理水平偏低的现象,因此推进自来水公司信息化管理已经成为供水行业发展的必然趋势。针对自来水公司的信息化需求开发了基于EPANET和ArcObjects的在线供水管网计算系统,该系统把EPANET、ArcGIS和数据库有效地结合起来,然后通过.NET框架封装为服务最终发布到Web平台上。该系统功能性强、开发成本较低,并且可以通过连接SCADA监控数据实时计算供水管网的运行状态,为供水管网模型的实时运行调度提供指导,符合供水行业当下需求。     

多水源管网供水分区的可视化研究

利用图论原理，根据管网水力计算结果，介绍了一种有关多水源管网供水分区的方法，并利用Visual Basic语言实现了管网供水分区的可视化显示，对运行管理人员进行管网水量调配和设计人员进行管网改造具有指导作用。     

基于BP神经网络的供水管网分时段宏观模型研究

准确快速地模拟供水管网的运行状态是城市供水系统优化调度的前提和关键。针对城市供水管网建模难的状况，结合南京市供水管网的特点，利用BP神经网络建立了城市供水管网分时段宏观等效模型。经实际运行数据验证，该模型计算得到的压力预测值与实际值非常接近，预测误差能满足优化调度的工程精度要求。可见该模型基本上能反映南京市供水管网的供水量与水压的关系，可用以模拟城市供水管网的运行状态，为管网优化调度提供了有力支持。     

基于延时模拟的供水管网可靠性分析

提出了一种基于延时模拟的供水管网可靠性评估模型.该模型不仅考虑到一天内用户用水量的变化,而且考虑到管网组件故障的随机性,并采用随机模拟的方法对各个节点和供水管网系统的可靠度分别进行计算,能够较为客观、真实地反映供水管网系统的可靠程度.模型的实例应用结果也证明了其实用性和合理性.     

数据中心环状空调水系统计算分析

大型数据中心空调设计通常采用水冷冷水系统,需满足出现单点故障时,不影响制冷系统正常运行。空调水系统多设计为环状管网、双立管系统,因此,多环路、双向供水管网的水力计算分析成为难点。针对某数据中心,介绍了一种可行的计算方法,即管网平差法。利用管网平差法借助Excel中VBA编程,分别对供水管网、回水管网进行水力计算分析。同时,考虑常规计算处理方法即多点故障断开为支状管网进行水力计算。通过对比分析可知,利用管网平差法计算的水泵扬程比常规计算方法减小27.6%,有利于设计时水泵的选型。     

城市供水管网系统分区改造模式的研究

通过分析我国城市供水管网的现状，阐述了管网分区的含义，指出分区供水是提高供水优化调度效率的基础，并介绍了以供水分界线和节点压力为依据的分区方法，以及区域内部、区域间的规划。通过管网分区，各管段的功能明确，易于区域计量及压力控制。整个管网系统便于优化调度，减小管网的漏失，提高经济效益。     

塑料管材供水管网水力计算方法的探讨

根据塑料供水管网的水流特点及其水头损失计算公式 ,确定了塑料供水管网将沿线流量折算成节点流量的折算系数的取值 ,采用有限元法分析塑料管材供水管网的水力平衡计算数学模型 ,由各个管段的单元矩阵方程集合为供水管网的整体矩阵方程 ,通过引入节点水压边界条件并迭代求解管网整体矩阵方程—对称正定线性方程组 ,得出各项水力要素 .给出了计算程序框图 ,编写了通用电算程序 ,经实例计算表明 ,该方法能够快捷准确地完成塑料供水管网的水力平衡计算 ,满足设计计算要求 .     

DECOVALEX III BMT3/BENCHPAR WP4: The thermo-hydro-mechanical responses to a glacial cycle and their potential implications for deep geological disposal of nuclear fuel waste in a fractured crystalline rock mass

A number of studies related to past and on-going deep repository performance assessments have identified glaciation/deglaciation as major future events in the next few hundred thousand years capable of causing significant impact on the long term performance of the repository system. Benchmark Test 3 (BMT3) of the international DECOVALEX III project has been designed to provide an illustrative example that explores the mechanical and hydraulic response of a fractured crystalline rock mass to a period of glaciation. The primary purpose of this numerical study is to investigate whether transient events associated with a glacial cycle could significantly influence the performance of a deep geological repository in a crystalline Shield setting. A conceptual site-scale (tens of kilometres) hydro-mechanical (HM) model was assembled based primarily on site-specific litho-structural, hydrogeological and geomechanical data from the Whiteshell Research Area in the Canadian Shield, with simplification and generalization. Continental glaciological modelling of the Laurentide ice sheet through the last glacial cycle lasting approximately 100,000 years suggests that this site was glaciated at about 60 ka and between about 22.5 and 11 ka before present with maximum ice sheet thickness reaching 2500 m and maximum basal water pressure head reaching 2000 m. The ice-sheet/drainage model was scaled down to generate spatially and temporally variable hydraulic and mechanical glaciated surface boundary conditions for site-scale subsurface HM modelling and permafrost modelling. Under extreme periglacial conditions permafrost was able to develop down to the assumed 500-m repository horizon. Two- and three-dimensional coupled HM finite-element simulations indicate: during ice-sheet advance there is rapid rise in hydraulic head, high transient hydraulic gradients and high groundwater velocities 2–3 orders of magnitude higher than under nonglacial conditions; surface water recharges deeper than under nonglacial conditions; upon ice-sheet retreat, the gradients reverse; fracture zone network geometry, interconnectivity and hydraulic properties significantly influence flow domain response; residual elevated heads are preserved for 10,000 s in the low-diffusivity rock; and no hydraulic jacking or shear failure occurs at depth. It was found that transient coupled modelling is necessary to capture the essence of glacial effects on Performance Assessment. Model dimensionality also significantly affects simulated results.     

Hydraulic Performance of Completely Mixed Tanks in Series under Unsteady Flow

Completely mixed tanks in series are often used in water and wastewater treatment processes and surface-water quality modelling. Hydraulic retention time, which describes the overall hydraulic performance of the tanks, is one of the main parameters in the design and operation of treatment processes and modelling of the surface-water quality. Differential equations to calculate the hydraulic retention time of completely mixed tanks in series under unsteady flow were derived in this study, and the equations were subsequently used to evaluate the hydraulic performance of tanks under a step change inflow rate and a cyclical flow rate, respectively. For a step change in flow rate, the differential equations were solved analytically using a recursive method. For a cyclical hydraulic loading, computer simulation was carried out using the Runge-Kutta method with adaptive stepsize control.     

Sankey Brook Catchment Study

The Sankey Brook catchment lies in the heart of the Mersey basin. As part of a major study into development issues in the Sankey Brook catchment, a hydraulic model was constructed and successfully used to simulate the river system and to assist in the derivation of discharge control policies.
The background to the study and the subsequent hydrological and hydraulic modelling are described, particularly in relation to the more complex systems in the lower reaches of Sankey Brook.     

ANOMALOUS RESPONSE IN THE HALIFAX PROCESS

The Halifax process was first proposed as a means of minimising the bulking of activated sludge. In one system using this process, bulking continued to occur. An analysis of the process, using dynamic modelling tools, predicted that the process contains the potential for effluent quality to become worse as the hydraulic loading to the process is reduced — contrary to common experience with more conventional layouts.     

The USEPA's distribution system water quality modelling program: a historical perspective

Hydraulic and water quality models have become widely used to understand both the hydraulic behaviour, and the fate and transport of contaminants in drinking water distribution systems. Research conducted by the United States (US) Environmental Protection Agency (EPA) played a major role in the development and application of hydraulic/water quality modelling in the United States and throughout the world. Eventually this research led to the development of EPANET, an integrated hydraulic/water quality model, and had a major influence on the implementation of the United States Safe Drinking Water Act (SDWA). The modelling research conducted by the US EPA has helped many drinking water utilities throughout the world alleviate public health threats due to the deterioration of water quality in drinking water networks. The US EPA has provided over 100 000 downloads of the EPANET software over the last 2 years.     

普通砼及陶粒砼的受拉断裂特性

本文采用Instron 1343型电液伺服试验机,控制应变速度,对不同品种(普通砼、陶粒砼)、不同强度的配筋及不配筋砼试件进行拉伸试验,得到了稳定而完整的砼拉伸应力-变形全曲线及其断裂能量G_F。研究了砼品种、强度、配筋等因素对受拉断裂特性的影响,并提出了砼受拉断裂的本构模型。     

英国排水管网建模技术实例分析

基于排水管网水力模型软件(InfoWorks CS),介绍了一个英国小城镇排水管网建模过程.在实例中详述了英国管网建模规范、数据管理、模型构建以及模型检验等方面内容,最后针对我国现阶段的排水管网建模提出了值得借鉴的地方.     

Performance assessment of a nuclear waste repository: Upscaling coupled hydro-mechanical properties for far-field transport analysis

A methodology for addressing the DECOVALEX III Bench Mark Test 2 is presented. Hydro-mechanical (HM) modelling has been conducted on fracture networks generated from fracture length and density statistics, which have been described by a power law. For each rock formation in the test, effective hydraulic conductivity tensors have been derived for a range of mechanical parameters and depths below ground level. The upscaled hydraulic conductivities have been used in a site scale continuum model of groundwater flow and transport to assess performance indicators, including time of travel from repository to ground surface. Preliminary results indicate that interpretation of the fracture length and density data can have a significant effect on upscaling calculations, including the determination of a suitable hydraulic representative elementary volume. HM modelling shows that there is a non-linear decrease in the change of fracture aperture with depth, and that although large aperture fractures remain at depth, the majority of fractures tighten to almost the residual aperture at about 750 m below ground level. Consequently, anisotropy of the effective hydraulic conductivity also changes with depth. Flow and transport modelling at the field scale indicates that, of the controls investigated, mechanical properties of the rock have the greatest influence on solute travel times.     

An improved understanding of canal hydraulics and flood risk from breach failures

British Waterways (BW) is the largest navigation authority in the UK, managing a network of 3200 km of inland waterway. Central to this function is the management of a complex water supply system, where water is transferred for resource management, to maintain navigation and for sale to third parties. The navigations also provide land drainage, with 30% of the English and Welsh catchments draining, into the network. Understanding the hydraulic mechanisms present is essential to manage the risks to infrastructure, land, property and personnel. This paper describes studies that have reduced the uncertainty of the hydraulic appraisals of canals. A programme of primary research included site surveys, hydraulic trials and modelling. Hydraulic roughnesses for a range of canal channel types were derived and the impact of structures was quantified. The paper then applies these findings to investigate a recent canal breach. Importantly, in terms of the hydraulic appraisal, pound water levels and flows were automatically monitored throughout the event. The breach was modelled via an innovative dual weir approach. The modelled water level drawdown compared very closely with that measured. In conclusion, this paper illustrates the major steps forward that BW has made in developing the understanding of canal hydraulics and breach failures. This paper is of interest to consultants, researchers and other workers who study canal hydraulics and flood risk throughout the UK and overseas.     

Impact of combined sewer overflow on urban river hydrodynamic modelling: a case study of the Chicago waterway

Combined sewer overflow (CSO) can be a critical inflow source for urban rivers during storm events. This paper presents a case study of the Chicago waterway. A three-dimensional (3D) river hydrodynamic model was developed and integrated with an urban rainfall-runoff model using the Open Modelling Interface (OpenMI). Both the effects of CSO discharge on river and river water levels on CSO outlets were considered by the integrated model. A historical storm, which was similar to a 100-year return period rain event, was simulated and compared with field measurements. This study highlights the necessity of quantifying CSO for hydraulic modelling of urban rivers under extreme storm event conditions, and shows that an integrated hydrologic and hydraulic approach can be used to address this challenge. The 3D river hydrodynamic model can deal with the complex hydrodynamics at river confluences and provide better hydrodynamic results for water quality modelling in the future.