Reduced laying depths for supply mains

Laying of supply piping below ground involves heavy costs. This paper from the GDR Bauakademie, Institute of Construction and Civil Engineering, Leipzig, describes how the costs have been reduced by up to 30 percent as a result of reducing the minimum depths required, by reassessing piping statics (interaction of the load - soil -pipe system), and the precautions for irregular frost heave, which can be of decisive importance.     

普通快滤池气冲防回水装置的设计与应用

普通快滤池的冲洗方式常采用气水反冲洗,但由于反冲洗阀关闭不严,导致反冲洗管路系统进水,加装气冲防回水装置可以解决气冲管路的回水问题,且效果好、成本低．     

非开挖铺设和无砂铺设用塑料管

非开挖铺设和无砂铺设有许多益处，用这些技术可以比传统的铺设方法节约费用达60％，并且有利于环境保护。可以预期，这种技术的应用会越来越普遍。新的铺设技术，对于塑料管材及其材料提出了新的要求，而由此新开发的塑料管道系统大部分是基于复合管的。     

OPTIMAL MAINTENANCE SCHEDULING FOR WATER DISTRIBUTION SYSTEMS

The scheduling of maintenance for water distribution systems is a complex task encompassing a wide range of alternatives. The methodology presented in this paper can consider the major piping alternatives of replacing and cleaning, and relining. It also considers the potential of pumping improvements while accounting for the costs of maintenance, failure and operations for a multiple-period planning horizon. To solve the problem a nonlinear optimization model is linked with a network simulation model. The application showed that the procedure can determine solutions in reasonable times.     

集中-分散太阳能供热水系统在多层住宅中的设计应用

多层住宅生活热水采用集中-分散太阳能供热水系统,环保、节能、管道布置灵活、运行费用低、管理方便,可依据住户生活习惯、天气及季节变化设置控制要求,较大限度的利用太阳能;热水用水定额、冷水计算温度及系统全年节能百分数等参数的选取对初投资及系统运行效果影响较大,需要合理取值。     

A reconciliation of experimental and analytical results for piping systems

This paper is focused on developing experimentally validated models of piping components as well as a complete two story piping system. The damage in a piping system is characterized in terms of “First Leakage” based on the observations made in laboratory experiments. Monotonic and cyclic testing for pipe components of various sizes shows that the limit-state for leakage is governed predominantly by flexural deformations at the threaded and groove fit T-joints. As a first step in the validation process, the nonlinear models for the flexural behavior of T-joints are reconciled with the experimental results. Next, the validated component models are incorporated in the piping model for a two story sprinkler system. The system level piping model is then integrated with ceiling systems that interact with sprinkler heads. The complex piping ceiling system model is validated by comparison with the corresponding experimental data.     

影响PVC-U管材纵向回缩率的几个主要因素

概述了PVC U配方设计、管材模具、制管工艺等对PVC U管材纵向回缩率的影响;并从CaCO3的填加量及泡管拉伸比两大因素进行研究,结果表明,CaCO3填加量在一定范围内直接影响PVC U管材的纵向回缩率;泡管拉伸比的变化直接导致PVC U管材纵向回缩率的变化。     

土体渗透稳定性的填充系数分析计算方法

土体渗透稳定性研究包括地层构造特征、砂砾卵石管涌、互层土的层状管涌和自然界的不可抗力因素等几个方面,过去基本上只研究砂砾石的管涌问题。本文对管涌地层构造和层状管涌进行了分析。应用453个管涌试验资料,对现有的国内外7种砂砾石渗透定性分析计算方法进行了验证。提出了填充系数理论,制订了土体渗透破坏形式的填充系数判别式和管涌临界破坏坡降计算图。管涌研究成果在长江、黄河治理工程中应用并取得了明显效果,防洪、泄洪能力显著提高,长江航运能力也提高1.2倍以上,综合经济效益巨大。长此以往,类似1998年的长江特大洪水灾难,可望永远不再发生。     

Investigation into capital costs of HVAC systems

The initial capital outlay is one of the largest expenses of any HVAC system. Estimating these costs accurately is crucial to any HVAC economic analysis. In this article, initial cost models are investigated.A literature study reveals different methods for estimating initial costs. None of these are suitable for use during the conceptual design stage. They are either too simplified or require too detailed inputs. The use of “Pareto's Principle” to develop a suitable model is investigated in this paper.“Pareto's Principle” can be formulated to state that 20% of the equipment makes up 80% of the cost. This principle is tested by analysing some tender estimates. Although it appears to hold true, it is also evident that items like piping and ducting contribute significantly to installation costs. Accurate estimates can thus only be obtained by pricing each sub-system separately.Models are proposed for each subsystem of a typical HVAC system. All the proposed models are suitable for integration with QUICKcontrol and are applicable to a wide range of different HVAC systems.Estimating the costs of both the major capital equipment as well as the smaller sub-systems, is relatively simple. Air and water distribution systems are more problematic due to the number of variables. Without a fairly detailed design and costing model, no accurate cost predictions can be made.     

配管设计与施工配置分析

针对大型工业项目配管设计进行了探讨,分别介绍了配管设计应考虑的安全因素及配置要求,并阐述了配管接头处理方法和配管支架设置,以期指导实践,科学合理布置管道,确保生产安全运行。     

冷热水用聚丁烯管材的特性、质量要求及应用

介绍了聚丁烯(PB)管材的原料、生产工艺及特性。通过相应标准阐述对PB管材的质量要求,通过参考使用条件级别、使用条件级别和设计压力选择对应的管系列S值及预测静液压强度参照曲线来设计选用PB管材。     

聚烯烃管道系统的质量控制

本文以给水管、煤气管材为例 ,介绍了聚烯烃管材专用料、管材、管材和管件连接系统的质量控制方法 ,简述了各类管材的分级情况。     

汽车工厂公用管廊的合理设计

管廊敷设管道数量多、承载能力强、跨距大、管道安装维修方便、美观协调。汽车工厂公用管廊是为各车间用户输送各种能源介质的主动脉,在生产中起到举足轻重的作用。论文根据汽车工厂的特点,对于汽车工厂的公用管廊的布置、管廊中热力管道与常温管道的设计作了较全面的介绍与总结。     

深基坑内管涌的成因及其处理对策

在深基础施工中,由于地下水文、地质情况的复杂性,经常会碰到管涌等不利情况的发生,一旦形成管涌之后,管涌的泛水点迅速由小变大而使基础积水、泛砂,给施工带来不利影响。本文通过杭州下沙某项目在基础施工过程中发生管涌现象的分析,阐述了深基坑内管涌现象的成因及其处理对策。     

土石坝管涌破坏溃口发展数值模型研究

由于坝体、坝基本身的缺陷或者穿坝建筑物的影响,渗透破坏是土石坝常见的一种破坏形式,管涌破坏在渗透破坏中占有很大比例。前人虽对土石坝管涌进行了大量的研究,但对管涌发生后的发展过程及其破坏规律还缺乏深入的研究。首先通过对可动颗粒受力情况的分析,推导出可动颗粒的临界水力梯度和管涌发展过程中土体孔隙率的变化,然后采用水流运动能量方程推导出管涌发展过程中管涌通道流量和流速的发展变化过程,得出了管涌通道流量的计算方法以及孔流转化为堰流的控制条件。在此基础上,提出了一个模拟土石坝管涌发展过程的数学模型,该模型可同时考虑土体的颗粒级配和密实度对管涌发展的影响,建立流量、流速与孔隙率的变化关系,确定管涌过程中的流量过程线,与目前国内外已有的模型相比,更为合理地考虑土石坝筑坝材料性质对溃口发展过程的影响。已有的大坝溃口实测流量过程线证实了该模型的合理性。     

Effect of randomly distributed geofibers on the piping behaviour of embankments constructed with fly ash as a fill material

Today, fly ash is being used as a structural fill material in highway and railway embankments, for ash pond bunds, levees, filling low-laying areas etc. Seepage induced failures in the form of piping can weaken and affect the performance of an embankment constructed with fly ash as a structural fill material. This paper presents a study to examine the effect of randomly distributed geofibers on the piping behaviour of fly ash. In this study, a number of experiments were carried out for determining the seepage velocity and piping resistance of fly ash, mixed randomly with flexible polyester fibers having various dosages and lengths. Seepage velocity of flow of water through fly ash is calculated for each case and compared with an unreinforced fly ash. It was observed that fibers reduced the seepage velocity, increased the piping resistance of fly ash and delays the attenuation of piping phenomena considerably. Finally the mechanism by which discrete and randomly distributed fibers restrain piping of fly ash is explained with the fly ash fiber interaction.     

管道输送系统在固体物料运输中的应用

采用管道输送固体物料技术，在国外已有大量的应用实例，但是在国内尚处于起步阶段，是一项具有一定应用前景的新技术。本文根据国外管道输送固体物料技术的实际运行经验，并结合贵州瓮福磷矿磷精矿管道输送系统的建设过程，从运输方案比较、管道运输系统设计以及采用管道输送固体物料应注意的问题三个方面，阐述了管道输送在固体物料中的应用。     

Critical appraisal of piping phenomena in earth dams

This paper presents a comprehensive review of published literature on soil piping phenomena. The first tools to design earth dams to resist piping were developed during 1910–1935. Filter criteria for dispersive soils was refined in the 1970’s. Piping phenomena are generally defined as: (1) heave, (2) internal erosion, (3) backwards erosion, although other modes are possible. Recent work on piping highlights the limitations of the occurrence of piping and the role that design and construction may play in a large percentage of piping failures. Standardized laboratory procedures are available to assess piping potential in cohesive materials, but no such methods exist for non-cohesive soils. However, methods are available for evaluation of self-filtration potential. Recent advances in computer technology have facilitated the evaluation of seepage and deformation in embankments but computational methods for evaluation of piping potential are currently limited.      

双层堤基管涌破坏过程中上覆层渗透破坏发生发展的 试验与分析

利用室内试验模拟了刚性盖板下双层堤基渗透破坏的过程,研究了堤基发生管涌破坏后对上覆黏土层的影响。通过肉眼观察,照相机辅助拍摄及试验过程中测压管水位,流量和出砂量等的变化,分析了管涌过程中刚性盖板下黏土层破坏的发生及发展过程。堤基发生管涌破坏后,砂层上部细颗粒逐渐流失,形成强渗流通道并逐步向上游发展。渗流通道与上层黏土之间形成脱空,黏土层发生轻微沉降变形,在水流作用下产生不均匀变形导致黏土层中裂纹的产生并在水力劈裂作用下裂纹逐渐变成裂缝并越来越大,水流通过裂缝在塌陷黏土与刚性盖板之间急速流动,产生冲刷,破坏范围随管涌的发生向上游发展。黏土层的破坏促进了管涌的发生,而管涌通道不断向上游发展也加速了黏土层的破坏,两种过程相互作用,相互影响。     

蒸汽供热系统的优化输配运行

提出了多热源多环路蒸汽输配的优化模型，探讨了相应的求解方法，基于此编制了通用的计算机软件，并投入到一个实际工程中应用。实践应用表明，采用蒸汽输配的优化模型，来指导和技术管理多源多环路的蒸汽供热系统运行，不仅对保证生产供汽，而且对蒸汽输配方案的优选和实施，起到明显的作用。