共查询到19条相似文献，搜索用时 124 毫秒
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城市供水管网在地震时的连通可靠性分析 总被引：1，自引：0，他引：1
考虑地震作用效应和管道抗力的随机特性,建立了埋地管道单元的概率预测模型,评估其在地震时的震害状态。把供水管网系统简化为边权有向网络图,通过Monte Carlo随机模拟过程,近似再现管网中各管段的破坏状态,进而分别结合图论理论方法和模糊关系矩阵法,对管网进行连通可靠性分析。由于Monte Carlo模拟算法是以管网各节点与水源点处于连通状态的近似频率计算来代替精确概率分析,为获得稳定的计算结果,对所用算例进行了5000次模拟。算例分析表明,基于图论方法和模糊关系矩阵法得到的管网连通可靠性结果基本相等。 相似文献
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输水管网的破坏，会导致地震灾害的严重扩大，输水管网的震害预测，已有运用随机模糊网络进行关键段的分析和管路可靠性的分析方法。1），2）本文建议的模糊最危险路（或最可靠路）分析，把管段的可靠性概率，扩展为语言概率，从而可以很好地容纳模糊性，使输水管的震害预测更加合理，为城市抗震防灾服务。 相似文献
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考虑崩塌堆积体边坡岩土体参数随机性和模糊性,以及地震力双向性,建立一种边坡地震动力模糊可靠度计算方法,针对竖向地震力对崩塌堆积体边坡稳定可靠性的影响进行进一步研究。首先,选用动力有限元时程分析法计算出双向地震工况下崩塌堆积体边坡的响应特征,并运用模糊理论对强度参数进行模糊性处理;然后,根据Mohr-Coulumb强度准则构建边坡安全系数与可靠度的时程计算模型;最后,采用边坡地震可靠性评价新方法,通过MATLAB编写相应程序,实现计算和分析结果的快速输出。案例结果表明:新方法计算结果更加合理,对工程而言也更加安全;竖向地震作用均对崩塌堆积体边坡整体可靠性存在影响,但影响程度需根据工程实际情况进行分析。在算例工况下,竖向地震对崩塌堆积体边坡的可靠性影响很小,仅使得可靠度降低3.55%,因此,可仅考虑水平地震的影响。 相似文献
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基于蒙特卡罗法的城市燃气管网抗震连通可靠性分析 总被引：1，自引：0，他引：1
在对燃气管道进行地震反应判别的基础上,计算管道的抗震可靠度,并结合图论将城市燃气管网简化为源点、汇点和边线,建立管网简化模型。采用蒙特卡罗法对某六节点网络模型进行抗震连通可靠性分析,结果表明:随着迭代次数的增加,近似解以更小的误差接近精确解的概率更大;迭代次数取为5 000时,能够较好地满足精度要求。通过对连通性矩阵进行分析,探讨了设定源点提高目标汇点连通可靠度的可行性。最后,以保定市区的大型燃气管网为例,计算了Ⅶ~Ⅸ度地震烈度下管网的连通可靠度,对比了设定源点对汇点连通可靠度的影响,为该市燃气管网的震害预测和抗震优化提供参考。 相似文献
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《地震工程与工程振动》2021,41(4)
为了评估大区域供水管网的综合抗震能力,分析了城市供水管网脆弱性的影响因素,并基于行业年鉴等数据资源建立了中国大陆区域供水管网综合抗震能力分析数据库。利用突变理论和模糊综合评价模型,建立了区域供水管网抗震能力评估指标体系,提出了区域综合抗震能力评估方法,结合720个城市供水管网管材、场地类别、城市类别、抗震设防等数据和评估影响指标,计算了每个城市基础抗震能力、供水管网自身抗震能力和综合抗震能力指数。建立了区域基础抗震能力分级和供水管网综合抗震能力分类标准,对中国大陆城市供水管网进行了分级和分类。利用ArcGIS计算并绘制了区域基础抗震能力分级图和供水管网综合抗震能力分类图。 相似文献
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震后火灾是破坏性地震发生后城市面对的主要危害之一。对于城市中燃气管网,建立地震紧急处置系统尤为重要。在日本、美国和我国的台湾地区,均因城市天然气管网建立了紧急处置系统而取得了减轻地震次生火灾的实效。我国是多地震的国家,随着管道燃气的日益普及,地震紧急处置设施非常重要。本文采用美国Northridge2000小型地震燃气阀,结合所设计的一种燃气管道地震紧急处置装置,在昆明市区,分别用于4户民居小管径燃气管道和一个大管径燃气管道,开展燃气管道的地震紧急处置示范应用。进行的人工触发试验显示,紧急处置装置响应与预期的一致,但还需实际地震的检验。本文介绍了燃气管道地震紧急处置的设计和示范应用情况,并对我国开展相关工作需要解决的问题进行了讨论。 相似文献
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本文描述了用自动系统编制地震最大震级Mmax预报图的方法。原始资料包括:地震震中图、潜在地震活动的地质地球物理特征图和一些地点(选择点)的Mmax专家评价。用以预报Mmax的地质地球特征函数是通过对选择点上的Mmax专家评价最优逼近得到的。Mmax图的编制需经过若干次迭代。电子计算机用来筛选含有最大信息量的特征,计算预报函数,自动分析评价处理结果并提出便于专业人员利用的图解、表格和地图等形式的结果。专门人员负责控制计算过程,备好原始资料,对结果进行分析和说明,判断是否有必要修正预报图以及将变更部分存入原始资料以期预报图下轮迭代后更趋准确。简略描述了计算程序软件包。列举了克里米亚—高加索—西土库曼地区Mmax预报图的编制实例。 相似文献
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供水管网的抗震功能是指供水管网在地震作用下能够满足震后城市特定用水需要（需水量和水压）的能力。地震发生后,供水管网一般处于低压供水状态,使得管网中部分用户的水压和水量不能得到全部满足,导致管网部分节点的实际配水量小于需水量。为此,在传统的管网水力分析基础上考虑节点流量随节点水压的动态变化,通过求解非线性水力方程组,得到管网节点实际流量和水压;同时,借鉴结构可靠度分析方法,引入供水管网系统随机水力模型,给出了震后供水管网功能可靠度分析的一次二阶矩方法。以一实际管网为例,演示了震后低压供水时管网功能可靠度分析的应用方法。 相似文献
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突发地震灾害下,城市供水管网往往不可避免地会发生不同程度的破坏而导致城市供水功能的失效,对人们的生产生活产生了严重影响,快速对震后城市供水管网进行科学合理的功能修复,对于降低地震灾害损失具有重要意义。本文以城市供水管网为对象,针对震后管网系统功能评价及快速修复决策等问题进行了研究。在中国点式渗漏模型的基础上,采用基于破坏概率的渗漏面积计算方法,建立了考虑地震破坏随机性的管线渗漏流量计算模型;针对震后破坏管线展开了水力分析,并提出了以节点水头损失比为指标的节点服务性能失效状态量化方法;进而建立了震后管线的修复决策模型以及功能修复费用模型。研究成果可为震后功能修复工作中管线修复顺序及修复方案的优选提供科学依据,可显著提高震后应急救灾效率,实现城市供水功能的快速修复。 相似文献
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This paper proposes an approach to estimate reliability of a storm water drain (SWD) network in fuzzy framework. It involves: (i) use of proposed fuzzy Monte-Carlo simulation (FMCS) methodology to estimate fuzzy reliability of conduits in the network, (ii) construction of a reliability block diagram (RBD) for the network (system) using suggested guidelines, and (iii) use of the RBD and reliability estimates of the conduits in the network to compute system reliability based on a proposed procedure. In addition, a system reliability based methodology is proposed for design/retrofitting of SWD network by optimization of its conduit dimensions. Conventionally used reliability analysis approaches assume that the cumulative distribution function (CDF) of performance function (marginal safety) of conduits follows Gaussian distribution, which cannot be ensured in the real world scenario. The proposed approach alleviates the need for making such assumptions and can account for linguistic ambiguity in variables defining the performance function. Effectiveness of the proposed approach is demonstrated on a hypothetical SWD network and a real network in Bangalore, India. Comparison of the results obtained from the proposed approach with those from conventional Monte-Carlo simulation (MCS) reliability assessment approach indicated that the estimate of system reliability and conduit reliability are higher with FMCS approach. Consequently, conduit dimensions required to attain required system (network) reliability could be expected to be lower when FMCS approach is used for designing or retrofitting a system. 相似文献
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根据概率可靠性理论,计算了地震作用下地下直埋管道的各个震害等级的概率值。假定在一段管子中,其破坏为泊松公布,求得这段管道供水的可靠性,最后用并联和串联分析法,得出整个供水管网的供水可靠性。通过实际计算,结果较理想。 相似文献
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We present a framework for the seismic risk assessment of water supply networks, operating in either normal or abnormal conditions. We propose a methodology for assessing the reliability of water pipe networks combining data of past non‐seismic damage and the vulnerability of the network components against seismic loading. Historical data are obtained using records of damages that occur on a daily basis throughout the network and are processed to produce‘survival curves’, depicting their estimated survival rate over time. The fragility of the network components is assessed using the approach suggested in the American Lifelines Alliance guidelines. The network reliability is assessed using graph theory, whereas the system network reliability is calculated using Monte Carlo simulation. The methodology proposed is demonstrated both on a simple, small‐scale, network and also on a real‐scale district metered area from the water network of the city of Limassol, Cyprus. The proposed approach allows the estimation of the probability that the network fails to provide the desired level of service and allows the prioritization of retrofit interventions and of capacity‐upgrade actions pertaining to existing water pipe networks. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
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An urban water supply network(WSN)is a crucial lifeline system that helps to maintain the normal functioning of modern society.However,the hydraulic analysis of a significantly damaged WSN that suffers from pipe breaks or leaks remains challenging.In this paper,a probability-based framework is proposed to assess the functionality of WSNs in the aftermath of powerful earthquakes.The serviceability of the WSN is quantified by using a comprehensive index that considers nodal water flow and nodal pressure.This index includes a coefficient that reflects the relative importance of these two parameters.The demand reduction(DR)method,which reduces the water flow of nodes while preventing the negative pressure of nodes,is proposed.The difference between the negative pressure elimination(NPE)method and the DR method is discussed by using the example of a WSN in a medium-sized city in China.The functionality values of the WSN are 0.76 and 0.99 when nodal pressure and nodal demands are used respectively as the index of system serviceability at an intensity level that would pertain to an earthquake considered to occur at a maximum level.When the intensity of ground motion is as high as 0.4 g,the DR method requires fewer samples than the NPE method to obtain accurate results.The NPE method eliminates most of the pipes,which may be unrealistic. 相似文献
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Lifeline systems, such as water distribution and gas supply networks, usually cover large areas. For these systems, seismic design is always a difficult problem because of the complexity of large‐scale networks. In this paper, a topology optimization technology for lifeline networks is established. Firstly, in order to speed up the convergence of optimization process, an element investment importance analysis is carried out to evaluate the importance of components to the lifeline network. Then a topology optimization model is established. The aim of the model is to find the least‐cost network topology while the seismic reliability between the sources and each terminal satisfies prescribed reliability constraints. For this optimization problem, a genetic algorithm, which takes network topologies as the individuals of its population, is used to search for the optimal solutions by suitable operators, including selection, crossover and mutation operators. The capacity of the proposed algorithm is illustrated by its applications to a simple example network consisting of 10 nodes and an actual network with 391 nodes located in a large city of China. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
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Assessing the efficiency of combined use of surface water and groundwater for process water supply to Kalininskaya NPP 总被引：2，自引：0，他引：2
The potential improvement of the reliability of process water supply system is discussed for the case of an important power
facility with the use of combined water intake systems. Hydrological simulation is used to determine the deficiency periods
of surface water resources and, accordingly, the period of involvement of subsurface compensation water intake. A hydrodynamic
model is used to predict the damage to surface runoff caused by the operation of the groundwater intake. The results are used
to prepare an operations schedule for the management of combined water intake system. 相似文献