中英文对照外文翻译
(文档含英文原文和中文翻译)
Short and Long Term Advantage roof drainage design performance Decade has witnessed great changes in the design of the roof drainage system recently, particularly, siphon rainwater drainage system has been gradually improved, and there is likely to be the key application. At the same time these changes, urban drainage system design has undergone tremendous changes, because the scope of a wider urban drainage system design for sustainable development, as well as people for climate change flooding more attention. The main contents of this article is how to design roof drainage systems and make a good performance. Special attention is how to get rid of bad habits already formed the design, but also need to consider innovative roof drainage system, such as green roofs and rainwater harvesting systems.
Practical application: In the past few years, the design of the roof rainwater drainage system has undergone tremendous changes. On large buildings, siphon rainwater drainage technology has been very common, as well as green roofs because it is conducive to green development, being more and more applications. Taking into account the ongoing research, this article focuses on how to effectively design a variety of roof rainwater drainage system, and make it achieve the desired design effect.
1. Introduction
In the past decade, the city and the water drainage system design has been widely accepted thinking about sustainable urban drainage system, or the optimal management direction. The main principles of the design of these systems is both a local level in line with the quality of development, but also to create some economic benefits for the investors. This principle has led to the development of new changes in the sump. Although the application of such a device is
gradually reduced, but the urban environment relatively high demand areas still require 100% waterproof and rapid drainage, such as the roof. Typically roof drainage system in the design, construction and maintenance has not been given due attention. Although the drainage system investment costs account for only a small portion of the total construction investment, but not able to judge the loss caused by poor design.
There are two different forms of roof drainage system design methods, namely the traditional and siphon method. Traditional systems rely on atmospheric pressure work, the drive ram affected sink flow depth. Therefore, the conventional roof drainage systems require a relatively large diameter vertical drop tube, prior to discharge, all devices must be connected to the groundwater collection pipe network. In contrast, siphonic roof drainage pipe systems are generally designed to full flow (turbulent flow means that require less exhaust pipe), which will form a negative pressure, the larger the higher flow rate and pressure head. Typically siphon system requires less down pipe work under negative pressure to the water distribution network can mean higher altitude work, thereby reducing the amount of underground pipe network.
Both systems consists of three parts: the roof, rainwater collection pipes, pipe network.
All of these elements are able to change the water pressure distribution system. This section focuses on the role and performance of each part. Due to the principle of siphon system has not been well understood, resulting argument is relatively small, this article will highlight siphon system.
2. Roof
The roof is usually designed by the architect, designer and not by the drainage design. There are three main roof.
2.1 Flat roof
Flat roofs are used in industrial buildings less rainfall regions and countries. This roof is not completely flat, but lower than the minimum roof slope may require. For example, the United Kingdom require maximum slope of 10 °. Setting minimum slope in order to avoid any unnecessary water.
Despite the flat roof if it is not properly maintained will have more problems, but it will reduce the dead zone within the building, and the ratio of sloping roofs in favor of indoor air.
2.2 sloping roofs
Most residential and commercial buildings are pitched roof, inclined roof is the biggest advantage can quickly drain, thereby reducing leakage. In temperate regions, we need to consider carrying roof snow load. Once it rains, rainfall through the sloping roofs can be determined by calculation. When rainfall data can be used, you can use the kinematic theory to solve such problems.
2.3 green roof (flat or inclined)
It can prove roof is the oldest green roofs, including rainfall can reduce or disperse roof planted with plants. It can be planted with trees and shrubs roof garden, it can also be a vegetated roof light carpet. Wherein the latter technique has been widely used. Some of these applications tend to focus on aesthetic requirements and are often used in green development. Since the aesthetic requirements and pressure requirements, as well as green roofs thermal insulation function, reduce the heat island effect, silencer effect, extend the life of the roof.
Green roofs in Germany, the most widely used, followed in North America, but to consider the impact on the aesthetics. Germany is by far the most experienced countries in the 19th century
have practical application, then as an alternative to reduce the risk of fire tar roof an option in urban areas. Germany is currently the main research question on the cultivation of other issues to consider smaller cities. A study from 1987 to 1989, was found packed with 70 mm thick green roof can be reduced by 60% -80% of heat loss. In a Canadian work computer model based on the roof indicates that as long as the sump, the area can reach 70% of the roof area can be reduced by 60 percent in one year, the same model was also used for artificial rainfall, which the results indicate that rainfall in the catchment season helps to drain away rainwater.
However, none of these studies show that green roofs can play a useful role in the rainfall season, or how high collection efficiency of water supply. The United States did some tests, as long as the green roofs regular watering, can reduce 65 percent of the runoff in a rainfall. America's most authoritative green roof guidelines by the New Jersey state environmental agencies promulgated. The main principle is to solve the structural problems of light, and how can the normal drainage after two years.
Rainfall period is based on the probability of failure is determined. The system is typically based on rainfall during rainstorms two minutes, two minutes, have a choice. Although this model will get more traffic, but there is no other better alternative. Studies have shown that the traditional model is applied to study green roofs are premature.
Loss factor than traditional roof records should be small, about 98.7%.
Peak flow will be reduced, although not penetrate, the surface roughness but also have a significant impact.
Concentrated rainfall than two minutes for a long time, especially for large roof areas, such as public buildings, commercial buildings, industrial buildings.
Urban drainage design should also consider other factors, for a complex system, a green roof in a rain is not enough. Water flow duration curve shows a longer than traditional systems. And two independent and will affect between is possible, which requires a more precise time period. 3. Rainwater Collector
Basic requirements rainwater collector is designed to be able to accommodate rainfall rainstorms. Although it is possible to make a slightly inclined roof drainage purposes, but the nature of the construction industry and building settlement will become flat roof Typically, the tank is placed in a horizontal, sectional view of the water is outwardly inclined, which the role of hydrostatic.
3.1 drain outlet
Analyzing rainwater collector has sufficient volume is the key to the sump outlet external setting conditions. Also affect the flow rate into the storm water drainage system piping, but also affect the depth of the water catchment. Although the depth of the sump will not bring any particular problems, but too deep can cause excessive sump.
Numerous studies in the 1980s showed that the flow of conventional roof drainage system outlet can be divided into two cases. It depends on the size of the depth and size of the outlet. When the water depth is less than half the diameter of the outlet, the flow of the first type, and the outlet of the flow can be calculated by an appropriate equation; water depth increases, exports are slowly clogging the flow will become another form forms, at the same time, the flow of exports can be obtained through other equations. While conventional roof drainage systems are designed to be free-draining, but may cause limitations encountered in the design of the flow is not free. In this case, it will require additional depth.
Siphon roof drainage systems, the outlet is designed to be submerged stream. In this case, the depth of the outlet of the decision is more complicated, because the design of the sump depends on the flow. Recent studies have shown that conventional roof drainage systems use a variety of non-standard catchment, their depth and height, bigger than the diameter of the outlet. This will eventually result in a siphon effect. For a given catchment, the flow depends on the starting end of the drop tube diameter. A similar phenomenon has also been used to study the standard catchment, in these circumstances, only limited siphon action occurs within relatively close distance from the exit.
3.2 tank flow classification
In the complex flow sump outlet flow classification, can be seen from Table 2a, the flow will be uniform layering, regardless of whether the same inlet flow. Table 2b and 2c show, export distribution will greatly influence the flow.
When the outlet is not a free jet, sump outlet complex flow classification is difficult to describe. Because each catchment tank pressures are likely to be merged. For example, the siphon tube system design point is at near full jet outlet flow classification depends on the energy loss of each branch.
3.3 hydrostatic sectional
Sump shape of the water surface in the canal can be classified according to the flow equation. In most cases, a low flow rate means that there is less friction loss, if exports are free jet, the friction loss is negligible cross-section through the hydrostatic equation 1 to determine the horizontal distance.
Where Q-- flow (m3 / s)
T- surface width (m)
g- acceleration of gravity (m / s2)
F- flow area (m2)
Equation 1 can not be ignored when the friction required to correct (or very long pipe velocity is large), or not a free jet.
3.4 The current design methods
The previous discussion has highlighted the main factors that should be considered with sink design. However, without the help of a certain number of models, computing hydrostatic sectional roof drainage system, the volume of the sump is possible. This large commercial and manufacturing industry, is a development opportunity, you can merge several kilometers of water routes. Thus, the conventional drainage system sump design methods are mainly based on experience, and assume that exports are free jet.
Sump location in the building, it may cause the example to fail.
Different interface sump
Except in the case cited above, but also allows designers to use empirical data.
3.5 Digital Model
Large number of digital models can be used to accurately describe the flow of any form of catchment tank, regardless of whether the roof flows stable. An example of this model is a combination of roof space model. This model enables users to classify different aspects of the data indicated, includes: details of the rains, the roof surface drainage and other details. Kinematics have also been used to study rainwater tank to flow from the research collection. A typical method is based on open system to solve a basic problem of spatial mobility. This model automatically
resolve the sump outlet flow situation, but also to deal with the case of free jet can also be simulated space limited mobility and submerged discharge. Output values include depth and flow rate.
Currently, the model is essentially just a variety of research tools, but also through practical engineering test. However, we should face up to the various role models.
4 pipe systems group
Composition in the form and scope of the tube group determines the roof drainage system relies mainly on the traditional system or siphon action.
4.1 Traditional stormwater systems
Conventional roof drainage systems, the ground plane is generally vertical pipe-line network, connected to the sump outlet and underground drainage systems, critical systems as well as compensating tube. It should be emphasized that the angle between the ground and the compensating tube is less than 10 °. Capacity of the entire system relies mainly on the outlet tube instead of down.
Flow vertical tube is usually free-flowing, full of only 33%, the efficiency depends on the excess length of the tube. If the drop tube long enough (typically greater than 5m), there may be an annular flow. Similarly, under normal circumstances flow compensation pipe is free-flowing, full of up to 70%. Such designed process both for the design, various equations can also be used.
4.2 Siphon roof drainage system
In contrast with the traditional drainage systems, Siphon roof drainage system relies on air flow outside the system, and the tube is full pipe flow stream.
The designs are usually made on the assumption that the design of heavy rain, the system can quickly siphon discharge rainwater. This assumption allows the application of hydrostatic siphon system theory. Often used steady flow energy equation. While this approach ignores the small amount of energy loss at the entrance, but after the experiment showed that there are still conducive to practical use.
However, steady-state design methods in the siphon system is exposed to rain when the system does not meet the standard requirements or changes in rainfall intensity is large is not applied. In the first case, there will be some mixing of air quality, annular flow occurs. These problems are not integrated in the system when more serious. Because usually designed rains are common, it is clear now design methodology over time may not apply to siphon system. This is a major disadvantage, because the design of the main problem is the noise and vibration problems.
Despite the disadvantages of the prior design approach, but a lot of the world's very few engineering failure reports. When a failure occurs, most likely for the following reasons: An incorrect understanding of the operation points
Substandard materials list
Installation defects
Maintenance mismanagement
To overcome these disadvantages, we have recently launched a series of research projects, to discuss the siphon system, and the development of digital models. From this work we learn a lot. In contrast with conventional design methods of some assumptions, siphon system mainly has the following aspects:
1) non-flow system of full flow
2) levels of certain pipe-flowing full pipe flow
3) full pipe flow downstream propagation through a vertical pipe, riser, etc.
4) the inner tube flow occurs over the vertical section, the system to reduce the pressure
5) downward tube is full pipe flow, there will be air lock
6) appears completely siphon action until well into the air system is lower than a certain level
Table 4a column data indicate that below the design point, the system will siphon unstable flow, depth of the water collecting tank is insufficient to maintain the siphon action. Table 4b show that the unsteady flow in siphon system when it will appear.
Table 5 lists the data output of a digital model. It can be seen that the model can accurately describe the siphon action, siphon and steady state, the data also show that the model can accurately describe the complex siphon action.
5 Conclusion
This article has illustrated the critical roof drainage systems, but these are often overlooked in the urban drainage system design. This article also shows that the design process is a complex process, rely mainly on the performance of exports. The following conclusions are based on the design summed up:
1) Run depend on three interacting parts: the roof, sump, water pipes
2) Green roofs can reduce traffic and beautify the city
3) the export performance of the system is essential
4) siphon drainage system have a greater advantage in large-scale projects, but must be considered high maintenance costs
5) Design siphon drainage system should consider additional capacity and operational issues
Although the green roof is a more attractive option, but the traditional roof of a building in the country will continue to dominate. Green roofs will be gradually developed, and gradually been widely accepted. Similarly, the roof drainage system shown effective that it will continue to play a huge role in the commercial building drainage systems.
Roof drainage system of the greatest threats from climate change, existing systems tend to be not simply aging; rainfall patterns of change will result in inefficient operation, self-cleaning rate will be reduced. Changes in wind speed and the roof will also accelerate the aging of the roof, it is necessary to carry out maintenance. Taking into account the climate change, the increase in materials, roof collected rainwater will be more extensive. Currently, the amount of rain around the globe per person per day 7-300 liters in the UK, with an average consumption of 145L / h / d, of which only about one liter is used by people, about 30 per cent of the toilet, study shows If water shortage, rainwater collected on the roof of developed and developing countries are recommended approach.
屋顶排水设计性能的近期与远期优势
最近十年见证了屋顶排水系统设计方面的巨大变化，特别的是，虹吸雨水排水系统已经得到逐步改善，并且有可能得到重点应用。发生这些变化的同时，城市排水系统设计已经发生了巨大的变化，因为适用范围更广的可持续发展城市排水系统设计，还有人们对于气候变化带来的洪水泛滥的更多关注。这篇文章的主要内容就是，如何设计屋顶雨水排水系统并使之有良好的运行性能。需要特别注意的是如何改掉已经形成的不良设计习惯，同时还要需要考虑屋顶排水系统的创新，如绿色屋顶和雨水收集系统。
实际应用：在过去几年，屋顶雨水排水系统的设计已经发生了巨大的变化。在大型建筑物上，虹吸雨水排水技术已经很常见，还有绿色屋顶由于其有利于绿色发展，正得到越来越多的应用。考虑到正在进行的研究，本文主要介绍如何有效地设计各种不同的屋顶雨水排水系统，并使其达到理想的设计效果。
1.绪论
在过去十年，城市与水排水系统设计已经想着广为接受的可持续发展城市排水系统或者最优管理方向发展。设计这些系统主要原则是，既要有符合当地发展水平的质量，又要为投资者创造一定的经济效益。这种原则已经引发了集水池发展方式新的变化。尽管这种装置的应用正在逐渐减少，但是城市环境要求比较高的地区仍然要求100%防水且排水迅速，例如屋顶。通常屋顶排水系统在设计、建造和维护时并没有受到应有的重视。尽管排水系统的投资费用只占建筑总投资的一小部分，但是，并不能据此来判断设计不良带来的损失。
主要有两种不同形式的屋顶排水系统设计方法，分别是传统的和虹吸式方法。传统的系统依靠大气压力工作，其驱动压头受到水槽流动深度的影响。因此传统的屋顶排水系统需要一个直径相当大的垂直下降管，在排放之前，所有的装置都必须连接到地下水收集管网。与此相反，虹吸式屋顶排水系统通常设计成满管流（紊流状态意味着只需要较小的排气管），从而会形成负压，较大的压头和较大的流速。通常虹吸式系统需要较少的下降管，在负压状态下工作，意味着给
水管网可以较高的高度上工作，从而减少地下管网量。
两种系统都由三部分组成：屋顶，雨水收集管道，系统管网。
所有这些部分都能够改变系统的水压分布。这部分主要关注各部分的作用和性能。由于虹吸系统的工作原理并没有得到很好的理解，得到的论证比较少，本文将会重点介绍虹吸系统。
2.屋顶
通常屋顶是由建筑师设计的，而不是由排水设计者设计的。主要有三种屋顶。
2.1平屋顶
平屋顶主要应用在降雨量比较少的地区和发达国家的工业建筑。这种屋顶并不完全是平的，而是低于所规定的屋顶最小坡度。例如，英国规定最大坡度为10°。设定最小坡度是为了避免任何不必要的积水。
尽管平屋顶如果得不到正确的维护会产生较多的问题，但它会减少建筑物内的死区，且比斜屋顶有利于室内气流组织。
2.2斜屋顶
大多数居住建筑和商业建筑都是斜屋顶，斜屋顶最大的优点是可以迅速排水，从而可以减少漏水。在温带地区，不需要考虑屋顶承载的降雪载重。一旦下雨，斜屋顶通过的降雨量就可以通过计算确定。当有降雨资料可以利用时，可以使用运动学理论来解决这类问题。
2.3绿色屋顶（平的或者是斜的）
可以证明最老的屋顶就是绿色屋顶，它包括可以减少或驱散降雨的种有植物的屋顶。它可以是种有树和灌木的屋顶花园，也可以是长有植被的轻型屋顶地毯。其中后一种技术已经得到广泛应用。其中一些应用趋向于侧重美学要求并经常应用于绿色发展。由于审美要求和水压要求，绿色屋顶还有热绝缘的功能，减少热岛效应，有消声作用，延长屋顶的使用寿命。
绿色屋顶在德国应用最为广泛，在北美地区次之，但是要考虑美学上的影响。德国是目前为止最有经验的国家，早在19世纪就有实际应用，当时作为在城市地区替代焦油屋顶降低火灾危险的一种选择。目前德国主要研究放在种植问题上，对城市的其它问题考虑较少。从1987年到1989年的一项研究工作，发现装有70毫米厚的绿色屋顶可以减少60%-80%的热损失。在加拿大的一项基于电脑
模型的工作，表明在屋顶只要集水器是、的面积能够达到屋顶面积的70%，在一年内就能减少60%，同样的模型也被用于人工降雨，其结果都表明集水器在降雨季有助于雨水排走。
但是这些研究都没有表明绿色屋顶在降雨季可以发挥多大的作用，或者给水管的收集效率有多高。美国做了一些测验，只要对绿色屋顶经常的浇灌，就可以在一次降雨中减少65%的径流量。美国最有权威的绿色屋顶指导原则是由新泽西州环保部门颁布的。这项原则主要是解决轻型结构问题，以及如何在两年之后还能正常的排水。
降雨周期是根据是根据失败的概率决定的。通常的系统是根据暴雨期间两分钟的降雨量，这两分钟是有选择的。尽管这种模型会得到更高的流量，但是没有其他更好的替代方法。研究表明，传统模型应用于绿色屋顶的研究是是不成熟的。
流失量系数比传统屋顶记录的要小，大约为98.7%.
峰值流量也会减少，虽然没有渗透，但是表面粗糙度也会产生显著的影响。
集中降雨的时间要比两分钟要长，特别是对面积较大的屋顶，如公共建筑、商业建筑、工业建筑。
城市排水设计还要考虑其他一些因素，对于一个复杂的系统来说，一个绿色屋顶在一场降雨中是不够的。流量水位曲线显示的持续期要比传统系统长。并且两场独立的将与之间的影响也是有可能的，这需要更加精确的时间周期。
3.雨水收集器
雨水收集器的基本要求是要能够容纳设计暴雨时的降雨量。尽管通常情况下可以通过让屋顶稍微倾斜来达到排水的目的，但是建筑工业的性质及建筑物的沉降都会式屋顶变得平坦，在水平放置的水槽中，水的剖面是向外倾斜的，这是流体静力学的作用。
3.1排水沟出口的深度
判断雨水收集器是否具有足够容积的关键是集水器外部出口的设置情况。还会影响流入雨水排水系统管道的流速，还会影响集水器的积水深度。尽管集水器的深度不会带来什么特别的问题，但是过深会导致集水器过高。
20世纪80年代的大量研究表明，传统屋顶排水系统的出水口的流动情况可以分为两种情况。这取决于水深与出口尺寸的大小。当水深小于出口直径的一半
时，流动情况是第一种类型，并且出口的流动情况可以通过合适的方程计算出；随着水深的增加，出口会被慢慢堵塞，流动形式会变成另一种形式，同时，出口的流动情况可以通过其他方程得出。尽管传统屋顶排水系统被设计成可以自由排水，但是设计中遇到限制可能会使出流不是自由的。在这种情况下，就会需要额外的深度。
在虹吸式屋顶排水系统中，出水口被设计成淹没出流，。在这种情况下，决定出水口的深度比较复杂的，因为集水器的设计取决于流动情况。近期的研究表明，传统的屋顶雨水排水系统使用各种非标准的集水器，它们的深度和高度，都要比出口的直径大。这最终会造成虹吸作用。对于一个给定的集水器，始端的流动情况取决于下降管的直径。类似的现象也被用于研究标准的集水器，在这些情况下，受限的虹吸作用只发生在离出口比较近的距离内。
3.2槽内的流动分类
在集水槽复杂流动出口的流动分类中，可以从表2a中看出，流动会出现均匀的分层，而不管入口的流动情况是否相同。表2b和2c表明，出口的分布会极大的影响流动情况。
当出口不是自由射流时，集水槽中复杂出口的流动情况分类是很难描述的。因为每个集水槽内的压力都有可能是合并的。例如，虹吸系统中的管子在靠近设计点时是充满射流，出口的流动分类取决于每个支路的能量损失。
3.3静水剖面
集水器中水表面的形状可以根据渠内流动方程进行分类。在大多数情况下，低流速意味着有较小的摩擦损失，如果出口是自由射流，那么摩擦损失是可以忽略的，静水剖面可以通过方程1来决定水平距离。
式中Q--流量(m3/s)
T—表面宽度（m）
g—重力加速度（m/s2）
F—流动面积（m2）
方程1在摩擦力不可忽略时需要进行修正（管道很长或流速很大时），或者不是自由射流。
3.4现行的设计方法
PA VEMENT PROBLEMS CAUSED BY COLLAPSIBLE SUBGRADES By Sandra L. Houston,1 Associate Member, ASCE (Reviewed by the Highway Division) ABSTRACT: Problem subgrade materials consisting of collapsible soils are com- mon in arid environments, which have climatic conditions and depositional and weathering processes favorable to their formation. Included herein is a discussion of predictive techniques that use commonly available laboratory equipment and testing methods for obtaining reliable estimates of the volume change for these problem soils. A method for predicting relevant stresses and corresponding collapse strains for typical pavement subgrades is presented. Relatively simple methods of evaluating potential volume change, based on results of familiar laboratory tests, are used. INTRODUCTION When a soil is given free access to water, it may decrease in volume, increase in volume, or do nothing. A soil that increases in volume is called a swelling or expansive soil, and a soil that decreases in volume is called a collapsible soil. The amount of volume change that occurs depends on the soil type and structure, the initial soil density, the imposed stress state, and the degree and extent of wetting. Subgrade materials comprised of soils that change volume upon wetting have caused distress to highways since the be- ginning of the professional practice and have cost many millions of dollars in roadway repairs. The prediction of the volume changes that may occur in the field is the first step in making an economic decision for dealing with these problem subgrade materials. Each project will have different design considerations, economic con- straints, and risk factors that will have to be taken into account. However, with a reliable method for making volume change predictions, the best design relative to the subgrade soils becomes a matter of economic comparison, and a much more rational design approach may be made. For example, typical techniques for dealing with expansive clays include: (1) In situ treatments with substances such as lime, cement, or fly-ash; (2) seepage barriers and/ or drainage systems; or (3) a computing of the serviceability loss and a mod- ification of the design to "accept" the anticipated expansion. In order to make the most economical decision, the amount of volume change (especially non- uniform volume change) must be accurately estimated, and the degree of road roughness evaluated from these data. Similarly, alternative design techniques are available for any roadway problem. The emphasis here will be placed on presenting economical and simple methods for: (1) Determining whether the subgrade materials are collapsible; and (2) estimating the amount of volume change that is likely to occur in the 'Asst. Prof., Ctr. for Advanced Res. in Transp., Arizona State Univ., Tempe, AZ 85287. Note. Discussion open until April 1, 1989. To extend the closing date one month,
转型衰退时期的土木工程研究 Sergios Lambropoulosa[1], John-Paris Pantouvakisb, Marina Marinellic 摘要 最近的全球经济和金融危机导致许多国家的经济陷入衰退，特别是在欧盟的周边。这些国家目前面临的民用建筑基础设施的公共投资和私人投资显著收缩，导致在民事特别是在民用建筑方向的失业。因此，在所有国家在经济衰退的专业发展对于土木工程应届毕业生来说是努力和资历的不相称的研究，因为他们很少有机会在实践中积累经验和知识，这些逐渐成为过时的经验和知识。在这种情况下，对于技术性大学在国家经济衰退的计划和实施的土木工程研究大纲的一个实质性的改革势在必行。目的是使毕业生拓宽他们的专业活动的范围，提高他们的就业能力。 在本文中，提出了土木工程研究课程的不断扩大，特别是在发展的光毕业生的潜在的项目，计划和投资组合管理。在这个方向上，一个全面的文献回顾，包括ASCE体为第二十一世纪，IPMA的能力的基础知识，建议在其他：显著增加所提供的模块和项目管理在战略管理中添加新的模块，领导行为，配送管理，组织和环境等；提供足够的专业训练五年的大学的研究；并由专业机构促进应届大学生认证。建议通过改革教学大纲为土木工程研究目前由国家技术提供了例证雅典大学。 1引言 土木工程研究（CES）蓬勃发展，是在第二次世界大战后。土木工程师的出现最初是由重建被摧毁的巨大需求所致，目的是更多和更好的社会追求。但是很快，这种演变一个长期的趋势，因为政府为了努力实现经济发展，采取了全世界的凯恩斯主义的理论，即公共基础设施投资作为动力。首先积极的结果导致公民为了更好的生活条件（住房，旅游等）和增加私人投资基础设施而创造机会。这些现象再国家的发展中尤为为明显。虽然前景并不明朗（例如，世界石油危机在70年代），在80年代领先的国家采用新自由主义经济的方法（如里根经济政策），这是最近的金融危机及金融危机造成的后果（即收缩的基础设施投资，在技术部门的高失业率），消除发展前途无限的误区。 技术教育的大学所认可的大量研究土木工程部。旧学校拓展专业并且新的学校建成，并招收许多学生。由于高的职业声望，薪酬，吸引高质量的学校的学生。在工程量的增加和科学技术的发展，导致到极强的专业性，无论是在研究还是工作当中。结构工程师，液压工程师，交通工程师等，都属于土木工程。试图在不同的国家采用专业性的权利，不同的解决方案，，从一个统一的大学学历和广泛的专业化的一般职业许可证。这个问题在许多其他行业成为关键。国际专业协会的专家和机构所确定的国家性检查机构，经过考试后，他们证明不仅是行业的新来者，而且专家通过时间来确定进展情况。尽管在很多情况下，这些证书虽然没有国家接受，他们赞赏和公认的世界。 在试图改革大学研究（不仅在土木工程）更接近市场需求的过程中，欧盟确定了1999博洛尼亚宣言，它引入了一个二能级系统。第一级度（例如，一个三年的学士）是进入
浮选柱处理含油废水的研究 摘要：本文介绍了一种为处理含油废水而开发的新型溶气浮选柱装置。溶气浮选柱将溶气气浮法和浮选柱巧妙的加以结合运用，溶解空气在柱体分离系统中释放。本文对这种具有潜在应用价值的柱体系统分离含油废水中油分的效果进行了研究，在一系列的 实验中该装置均取得了理想的分离效果，同时还对溶气浮选柱中采用的气泡产生器的曝气效果进行了专门研究。 关键词：含油废水；分离；气浮；气泡发生器；溶气浮选柱 一、引言 含油废水是石油开发利用过程中产生的面积广，数量大的污染源。废水中的油分包括浮油，分散油，乳化油，溶解油和油-固结合物。含油废水常用的处理技术有物理法、物理化学法、化学破乳法、生物化学法和电化学法。分离难易程度取决于油分在水体中的存在形式。含油废水中的浮油一般可以采用重力分离技术予以去除，溶解油可以通过生物处理法将其去除，而以胶体状态存在的分散油和乳化油由于其平均粒径小，化学稳定性咼而难以去除。 近年来，浮选技术由于具有分离效率高，资金投入少，运行费用低的特点而吸引了众多学者的关注，并且已经开发出一些新型的快速高效的含油废水处理装置。Feng P B 和其合作者开发出一种高效节能浮选柱进行含油废水处理，其油分的去除率可以达到90% 左右。GU Xuqing等人开发出一种新型多级环流式浮选柱可处理含油废水，其独特的流体环流模式极大的提高了油珠和气泡之间的接触几率，分离效果显著，5分钟内，分离 效率可以达到96%-97%0Xiao K L等人用多级浮选柱处理含油废水，空气分散在装置的柱体托盘底部，含油废水在柱体的各个托盘中进行处理，除油率达94%。 含有乳化油的废水处理较为困难，为保证浮选效率，分离时要求气泡粒径小，并且在分离区域中形成安静的水力学环境。分离区应当又长又窄这一概念引发了利用柱状体作为分离设备这一设计理念。由此产生了一种叫做溶气浮选柱的新型设备，溶解空气在该装置的柱体分离系统中析出，以此来处理含油废水。 二、材料与方法 （一）材料 实验废水是用胜利油田的脱水脱气原油配制的乳化油经过稀释得到的。水样经过三 十分钟的高速搅拌混合以保证油珠完全地分散到水中。采用激光粒度分析仪分析油珠的 粒径分布；平均粒径为18.15微米，约有77.8%的粒子的粒径在25微米左右或更小（图
零售企业营销策略中英文对照外文翻译文献(文档含英文原文和中文翻译)
译文： 零售企业的营销策略 Philip Kotlor 今天的零售商为了招徕和挽留顾客，急欲寻找新的营销策略。过去，他们挽留顾客的方法是销售特别的或独特的花色品种，提供比竞争对手更多更好的服务提供商店信用卡是顾客能赊购商品。可是，现在这一切都已变得面目全非了。现在，诸如卡尔文·克连，依佐和李维等全国性品牌，不仅在大多数百货公司及其专营店可以看到，并且也可以在大型综合商场和折扣商店可以买到。全国性品牌的生产商为全力扩大销售量，它们将贴有品牌的商品到处销售。结果是零售商店的面貌越来越相似。 在服务项目上的分工差异在逐渐缩小。许多百货公司削减了服务项目，而许多折扣商店却增加了服务项目。顾客变成了精明的采购员，对价格更加敏感。他们看不出有什么道理要为相同的品牌付出更多的钱，特别是当服务的差别不大或微不足道时。由于银行信用卡越来越被所有的商家接受，他们觉得不必从每个商店赊购商品。 百货商店面对着日益增加的价格的折扣店和专业商店的竞争，准备东山再起。历史上居于市中心的许多商店在郊区购物中心开设分店，那里有宽敞的停车场，购买者来自人口增长较快并且有较高收入的地区。其他一些则对其商店形式进行改变，有些则试用邮购盒电话订货的方法。超级市场面对的是超级商店的竞争，它们开始扩大店面，经营大量的品种繁多的商品和提高设备等级，超级市场还增加了它们的促销预算，大量转向私人品牌，从而增加盈利。 现在，我们讨论零售商在目标市场、产品品种和采办、服务以及商店气氛、定价、促销和销售地点等方面的营销策略。 一、目标市场 零售商最重要的决策时确定目标市场。当确定目标市场并且勾勒出轮廓时，零售商才能对产品分配、商店装饰、广告词和广告媒体、价格水平等作出一致的决定。如沃尔玛的目标市场相当明确：
姓名： 学号： 10447425 X X 大学 毕业设计（论文）外文翻译 （2014届） 外文题目Developments in excavation bracing systems 译文题目开挖工程支撑体系的发展 外文出处Tunnelling and Underground Space Technology 31 (2012) 107–116 学生XXX 学院XXXX 专业班级XXXXX 校内指导教师XXX 专业技术职务XXXXX 校外指导老师专业技术职务 二○一三年十二月
开挖工程支撑体系的发展 1.引言 几乎所有土木工程建设项目（如建筑物，道路，隧道，桥梁，污水处理厂，管道，下水道）都涉及泥土挖掘的一些工程量。往往由于由相邻的结构，特性线，或使用权空间的限制，必须要一个土地固定系统，以允许土壤被挖掘到所需的深度。历史上，许多挖掘支撑系统已经开发出来。其中，现在比较常见的几种方法是：板桩，钻孔桩墙，泥浆墙。 土地固定系统的选择是由技术性能要求和施工可行性（例如手段，方法）决定的，包括执行的可靠性，而成本考虑了这些之后，其他问题也得到解决。通常环境后果（用于处理废泥浆和钻井液如监管要求）也非常被关注（邱阳、1998）。 土地固定系统通常是建设项目的较大的一个组成部分。如果不能按时完成项目，将极大地影响总成本。通常首先建造支撑，在许多情况下，临时支撑系统是用于支持在挖掘以允许进行不断施工，直到永久系统被构造。临时系统可以被去除或留在原处。 打桩时，因撞击或振动它们可能会被赶入到位。在一般情况下，振动是最昂贵的方法，但只适合于松散颗粒材料，土壤中具有较高电阻（例如，通过鹅卵石）的不能使用。采用打入桩系统通常是中间的成本和适合于软沉积物（包括粘性和非粘性），只要该矿床是免费的鹅卵石或更大的岩石。 通常，垂直元素（例如桩）的前安装挖掘工程和水平元件（如内部支撑或绑回）被安装为挖掘工程的进行下去，从而限制了跨距长度，以便减少在垂直开发弯矩元素。在填充情况下，桩可先设置，从在斜坡的底部其嵌入悬挑起来，安装作为填充进步水平元素（如搭背或土钉）。如果滞后是用来保持垂直元素之间的土壤中，它被安装为挖掘工程的进行下去，或之前以填补位置。 吉尔- 马丁等人（2010）提供了一个数值计算程序，以获取圆形桩承受轴向载荷和统一标志（如悬臂桩）的单轴弯矩的最佳纵筋。他们开发的两种优化流程：用一个或两个直径为纵向钢筋。优化增强模式允许大量减少的设计要求钢筋的用量，这些减少纵向钢筋可达到50％相对传统的，均匀分布的加固方案。 加固桩集中纵向钢筋最佳的位置在受拉区。除了节约钢筋，所述非对称加强钢筋图案提高抗弯刚度，通过增加转动惯量的转化部分的时刻。这种增加的刚性可能会在一段时间内增加的变形与蠕变相关的费用。评估相对于传统的非对称加强桩的优点，对称，钢筋桩被服务的条件下全面测试来完成的，这种试验是为了验证结构的可行性和取得的变形的原位测量。 基于现场试验中，用于优化的加强图案的优点浇铸钻出孔（CIDH）在巴塞罗那的
项目成本控制 一、引言 项目是企业形象的窗口和效益的源泉。随着市场竞争日趋激烈，工程质量、文明施工要求不断提高，材料价格波动起伏，以及其他种种不确定因素的影响，使得项目运作处于较为严峻的环境之中。由此可见项目的成本控制是贯穿在工程建设自招投标阶段直到竣工验收的全过程，它是企业全面成本管理的重要环节，必须在组织和控制措施上给于高度的重视，以期达到提高企业经济效益的目的。 二、概述 工程施工项目成本控制，指在项目成本在成本发生和形成过程中，对生产经营所消耗的人力资源、物资资源和费用开支，进行指导、监督、调节和限制，及时预防、发现和纠正偏差从而把各项费用控制在计划成本的预定目标之内，以达到保证企业生产经营效益的目的。 三、施工企业成本控制原则 施工企业的成本控制是以施工项目成本控制为中心，施工项目成本控制原则是企业成本管理的基础和核心，施工企业项目经理部在对项目施工过程进行成本控制时，必须遵循以下基本原则。 3.1 成本最低化原则。施工项目成本控制的根本目的，在于通过成本管理的各种手段，促进不断降低施工项目成本，以达到可能实现最低的目标成本的要求。在实行成本最低化原则时，应注意降低成本的可能性和合理的成本最低化。一方面挖掘各种降低成本的能力，使可能性变为现实；另一方面要从实际出发，制定通过主观努力可能达到合理的最低成本水平。 3.2 全面成本控制原则。全面成本管理是全企业、全员和全过程的管理，亦称“三全”管理。项目成本的全员控制有一个系统的实质性内容，包括各部门、各单位的责任网络和班组经济核算等等，应防止成本控制人人有责，人人不管。项目成本的全过程控制要求成本控制工作要随着项目施工进展的各个阶段连续 进行，既不能疏漏，又不能时紧时松，应使施工项目成本自始至终置于有效的控制之下。 3.3 动态控制原则。施工项目是一次性的，成本控制应强调项目的中间控制，即动态控制。因为施工准备阶段的成本控制只是根据施工组织设计的具体内容确
Laminar and Turbulent Flow Observation shows that two entirely different types of fluid flow exist. This was demon- strated by Osborne Reynolds in 1883 through an experiment in which water was discharged from a tank through a glass tube. The rate of flow could be controlled by a valve at the outlet, and a fine filament of dye injected at the entrance to the tube. At low velocities, it was found that the dye filament remained intact throughout the length of the tube, showing that the particles of water moved in parallel lines. This type of flow is known as laminar, viscous or streamline, the particles of fluid moving in an orderly manner and retaining the same relative positions in successive cross- sections. As the velocity in the tube was increased by opening the outlet valve, a point was eventually reached at which the dye filament at first began to oscillate and then broke up so that the colour was diffused over the whole cross-section, showing that the particles of fluid no longer moved in an orderly manner but occupied different relative position in successive cross-sections. This type of flow is known as turbulent and is characterized by continuous small fluctuations in the magnitude and direction of the velocity of the fluid particles, which are accompanied by corresponding small fluctuations of pressure. When the motion of a fluid particle in a stream is disturbed, its inertia
顾客满意策略与顾客满意营销 原文来源：《Marketing Customer Satisfaction 》自20世纪八十年代末以来, 顾客满意战略已日益成为各国企业占有更多的顾客份额, 获得竞争优势的整体经营手段。 一、顾客满意策略是现代企业获得顾客“货币选票”的法宝随着时代的变迁, 社会物质财富的极大充裕, 顾客中的主体———消费者的需求也先后跨越了物质缺乏的时代、追求数量的时代、追求品质的时代, 到了20世纪八十年代末进入了情感消费时代。在我国, 随着经济的高速发展,我们也已迅速跨越了物质缺乏时代、追求数量的时代乃至追求品质的时代, 到今天也逐步迈进情感消费时代。在情感消费时代, 各企业的同类产品早已达到同时、同质、同能、同价, 消费者追求的已不再是质量、功能和价格, 而是舒适、便利、安全、安心、速度、跃动、环保、清洁、愉快、有趣等,消费者日益关注的是产品能否为自己的生活带来活力、充实、舒适、美感和精神文化品位, 以及超越消费者期望值的售前、售中、售后服务和咨询。也就是说, 今天人们所追求的是具有“心的满足感和充实感”的商品, 是高附加值的商品和服务,追求价值观和意识多元化、个性化和无形的满足感的时代已经来临。 与消费者价值追求变化相适应的企业间的竞争, 也由产品竞争、价格竞争、技术竞争、广告竞争、品牌竞争发展到现今的形象竞争、信誉竞争、文化竞争和服务竞争, 即顾客满意竞争。这种竞争是企业在广角度、宽领域的时空范围内展开的高层次、体现综合实力的竞争。它包括组织创新力、技术创新力、管理创新力、产业预见力、产品研发力、员工向心力、服务顾客力、顾客亲和力、同行认同力、社会贡献力、公关传播沟通力、企业文化推动力、环境适应力等等。这些综合形象力和如何合成综合持久的竞争力, 这就是CSft略所要解决的问题。CS寸代,企业不再以“自己为中心”,而是以“顾客为中心”；“顾客为尊”、“顾客满意”不再是流于形式的口号, 而是以实实在在的行动为基础的企业经营的一门新哲学。企业不再以质量达标, 自己满意为经营理念, 而是以顾客满意, 赢得顾客高忠诚度为经营理念。企业经营策略的焦点不再以争取或保持市场占有率为主, 而是以争取顾客满意为经营理念。因此, 营销策略的重心不再放在竞争对手身上而是放在顾客身上, 放在顾客现实的、潜在的需求上。当企业提供的产品和服务达到了顾客事先的期望值, 顾客就基本满意；如果远远超越顾客的期望值, 且远远高于其他同行, 顾客才真正满意；如果企业能不断地或长久地令顾客满意, 顾客就会忠诚。忠诚的顾客不仅会经常性地重复购买, 还会购买企业其它相关的产品或服务；忠诚的顾客不仅会积极向别人推荐他所买的产品, 而且对企业竞争者的促销活动具有免疫能力一个不满意的顾客会将不满意告诉16-20个人, 而每一个被告知者会再传播给12-15个人。这样, 一个不满意者会影响到二、三百人。在互联网普及的今天, 其影响则更大。据美国汽车业的调查, 一个满意者会引发8笔潜在的生意, 其中至少有一笔会成交。而另一项调查表明, 企业每增加5%的忠诚顾客, 利润就会增长25%-95%。一个企业的80%的利润来自20%的忠诚顾客；而获取一个新顾客的成本是维持一个老顾客成本的6倍。所以,美国著名学者唐?佩 珀斯指出: 决定一个企业成功与否的关键不是市场份额, 而是在于顾客份额。 于是, 企业纷纷通过广泛细致的市场调研、与消费者直接接触、顾客信息反馈等方式来了解顾客在各方面的现实需求和潜在需求。依靠对企业满意忠诚的销售、服务人员, 定期、定量地对顾客满意度进行综合测定, 以便准确地把握企业经营中与“顾客满意” 目标的差距及其重点领域, 从而进一步改善企业的经营活动。依靠高亲和力的企业文化、高效率的人文管理和全员共同努力, 不断地向顾客提供高附加值的产品, 高水准的亲情般的服
（ 二 〇 一 二 年 六 月 外文文献及翻译 题 目： About Buiding on the Structure Design 学生姓名： 学 院：土木工程学院 系 别：建筑工程系 专 业：土木工程(建筑工程方向) 班 级：土木08-4班 指导教师：
英文原文： Building construction concrete crack of prevention and processing Abstract The crack problem of concrete is a widespread existence but again difficult in solve of engineering actual problem, this text carried on a study analysis to a little bit familiar crack problem in the concrete engineering, and aim at concrete the circumstance put forward some prevention, processing measure. Keyword:Concrete crack prevention processing Foreword Concrete's ising 1 kind is anticipate by the freestone bone, cement, water and other mixture but formation of the in addition material of quality brittleness not and all material.Because the concrete construction transform with oneself, control etc. a series problem, harden model of in the concrete existence numerous tiny hole, spirit cave and tiny crack, is exactly because these beginning start blemish of existence just make the concrete present one some not and all the characteristic of quality.The tiny crack is a kind of harmless crack and accept concrete heavy, defend Shen and a little bit other use function not a creation to endanger.But after the concrete be subjected to lotus carry, difference in temperature etc. function, tiny crack would continuously of expand with connect, end formation we can see without the
专业资料 学院： 专业：土木工程 姓名： 学号： 外文出处：Structural Systems to resist (用外文写) Lateral loads 附件：1.外文资料翻译译文；2.外文原文。
附件1：外文资料翻译译文 抗侧向荷载的结构体系 常用的结构体系 若已测出荷载量达数千万磅重，那么在高层建筑设计中就没有多少可以进行极其复杂的构思余地了。确实，较好的高层建筑普遍具有构思简单、表现明晰的特点。 这并不是说没有进行宏观构思的余地。实际上，正是因为有了这种宏观的构思，新奇的高层建筑体系才得以发展，可能更重要的是：几年以前才出现的一些新概念在今天的技术中已经变得平常了。 如果忽略一些与建筑材料密切相关的概念不谈，高层建筑里最为常用的结构体系便可分为如下几类： 1.抗弯矩框架。 2.支撑框架，包括偏心支撑框架。 3.剪力墙，包括钢板剪力墙。 4.筒中框架。 5.筒中筒结构。 6.核心交互结构。 7. 框格体系或束筒体系。 特别是由于最近趋向于更复杂的建筑形式，同时也需要增加刚度以抵抗几力和地震力，大多数高层建筑都具有由框架、支撑构架、剪力墙和相关体系相结合而构成的体系。而且，就较高的建筑物而言，大多数都是由交互式构件组成三维陈列。 将这些构件结合起来的方法正是高层建筑设计方法的本质。其结合方式需要在考虑环境、功能和费用后再发展，以便提供促使建筑发展达到新高度的有效结构。这并
不是说富于想象力的结构设计就能够创造出伟大建筑。正相反，有许多例优美的建筑仅得到结构工程师适当的支持就被创造出来了，然而，如果没有天赋甚厚的建筑师的创造力的指导，那么，得以发展的就只能是好的结构，并非是伟大的建筑。无论如何，要想创造出高层建筑真正非凡的设计，两者都需要最好的。 虽然在文献中通常可以见到有关这七种体系的全面性讨论，但是在这里还值得进一步讨论。设计方法的本质贯穿于整个讨论。设计方法的本质贯穿于整个讨论中。 抗弯矩框架 抗弯矩框架也许是低，中高度的建筑中常用的体系，它具有线性水平构件和垂直构件在接头处基本刚接之特点。这种框架用作独立的体系，或者和其他体系结合起来使用，以便提供所需要水平荷载抵抗力。对于较高的高层建筑，可能会发现该本系不宜作为独立体系，这是因为在侧向力的作用下难以调动足够的刚度。 我们可以利用STRESS，STRUDL 或者其他大量合适的计算机程序进行结构分析。所谓的门架法分析或悬臂法分析在当今的技术中无一席之地，由于柱梁节点固有柔性，并且由于初步设计应该力求突出体系的弱点，所以在初析中使用框架的中心距尺寸设计是司空惯的。当然，在设计的后期阶段，实际地评价结点的变形很有必要。 支撑框架 支撑框架实际上刚度比抗弯矩框架强，在高层建筑中也得到更广泛的应用。这种体系以其结点处铰接或则接的线性水平构件、垂直构件和斜撑构件而具特色，它通常与其他体系共同用于较高的建筑，并且作为一种独立的体系用在低、中高度的建筑中。
文献出处: Dalman, M. Deniz, and Junhong Min. "Marketing Strategy for Unusual Brand Differentiation: Trivial Attribute Effect." International Journal of Marketing Studies 6.5 (2014): 63-72. 原文 Marketing Strategy for Unusual Brand Differentiation: Trivial Attribute Effect Dalman, M. Deniz & Junhong Min Abstract This research investigates that brand differentiation creating superior values can be achieved not only by adding meaningful attributes but also meaningless attributes, which is called "trivial attribute effect." Two studies provided empirical evidences as following; first, trivial attribute effect creates a strong brand differentiation even after subjects realize that trivial attribute has no value. Second, trivial attribute effect is more pronounced in hedonic service category compared to the utilitarian category. Last, the amount of willingness to pay is higher when trivial attribute is presented and evaluated in joint evaluation mode than separate evaluation mode. Finally, we conclude with discussion and provide suggestions for further research. Keywords: brand differentiation, evaluation mode, service industry, trivial attribute Introduction Problem Definition Perhaps the most important factor for new product success is to create the meaningful brand differentiation that provides customers with superior values beyond what the competitors can offer in the same industry (Porter, 1985). Not surprisingly, more than 50 percent of annual sales in consumer product industries including automobiles, biotechnology, computer software, and pharmaceuticals are attributed to such meaningful brand differentiation by including new or noble attributes (Schilling &Hill, 1998). However, the brand differentiation that increases consumer preference is not only by introducing meaningful attributes but also meaningless attributes. For
7 Rigid-Frame Structures A rigid-frame high-rise structure typically comprises parallel or orthogonally arranged bents consisting of columns and girders with moment resistant joints. Resistance to horizontal loading is provided by the bending resistance of the columns, girders, and joints. The continuity of the frame also contributes to resisting gravity loading, by reducing the moments in the girders. The advantages of a rigid frame are the simplicity and convenience of its rectangular form.Its unobstructed arrangement, clear of bracing members and structural walls, allows freedom internally for the layout and externally for the fenestration. Rig id frames are considered economical for buildings of up to' about 25 stories, above which their drift resistance is costly to control. If, however, a rigid frame is combined with shear walls or cores, the resulting structure is very much stiffer so that its height potential may extend up to 50 stories or more. A flat plate structure is very similar to a rigid frame, but with slabs replacing the girders As with a rigid frame, horizontal and vertical loadings are resisted in a flat plate structure by the flexural continuity between the vertical and horizontal components. As highly redundant structures, rigid frames are designed initially on the basis of approximate analyses, after which more rigorous analyses and checks can be made. The procedure may typically inc lude the following stages: 1. Estimation of gravity load forces in girders and columns by approximate method. 2. Preliminary estimate of member sizes based on gravity load forces with arbitrary increase in sizes to allow for horizontal loading. 3. Approximate allocation of horizontal loading to bents and preliminary analysis of member forces in bents. 4. Check on drift and adjustment of member sizes if necessary. 5. Check on strength of members for worst combination of gravity and horizontal loading, and adjustment of member sizes if necessary. 6. Computer analysis of total structure for more accurate check on member strengths and drift, with further adjustment of sizes where required. This stage may include the second-order P-Delta effects of gravity loading on the member forces and drift.. 7. Detailed design of members and connections.
学校 毕业设计（论文）附件 外文文献翻译 学号： xxxxx 姓名： xxx 所在系别： xxxxx 专业班级： xxx 指导教师： xxxx 原文标题： Building construction concrete crack of prevention and processing 2012年月日 .
建筑施工混凝土裂缝的预防与处理1 摘要 混凝土的裂缝问题是一个普遍存在而又难于解决的工程实际问题，本文对混凝土工程中常见的一些裂缝问题进行了探讨分析，并针对具体情况提出了一些预防、处理措施。 关键词：混凝土裂缝预防处理 前言 混凝土是一种由砂石骨料、水泥、水及其他外加材料混合而形成的非均质脆性材料。由于混凝土施工和本身变形、约束等一系列问题，硬化成型的混凝土中存在着众多的微孔隙、气穴和微裂缝，正是由于这些初始缺陷的存在才使混凝土呈现出一些非均质的特性。微裂缝通常是一种无害裂缝，对混凝土的承重、防渗及其他一些使用功能不产生危害。但是在混凝土受到荷载、温差等作用之后，微裂缝就会不断的扩展和连通，最终形成我们肉眼可见的宏观裂缝，也就是混凝土工程中常说的裂缝。 混凝土建筑和构件通常都是带缝工作的，由于裂缝的存在和发展通常会使内部的钢筋等材料产生腐蚀，降低钢筋混凝土材料的承载能力、耐久性及抗渗能力，影响建筑物的外观、使用寿命，严重者将会威胁到人们的生命和财产安全。很多工程的失事都是由于裂缝的不稳定发展所致。近代科学研究和大量的混凝土工程实践证明，在混凝土工程中裂缝问题是不可避免的，在一定的范围内也是可以接受的，只是要采取有效的措施将其危害程度控制在一定的范围之内。钢筋混凝土规范也明确规定：有些结构在所处的不同条件下，允许存在一定宽度的裂缝。但在施工中应尽量采取有效措施控制裂缝产生，使结构尽可能不出现裂缝或尽量减少裂缝的数量和宽度，尤其要尽量避免有害裂缝的出现，从而确保工程质量。 混凝土裂缝产生的原因很多，有变形引起的裂缝：如温度变化、收缩、膨胀、不均匀沉陷等原因引起的裂缝；有外载作用引起的裂缝；有养护环境不当和化学作用引起的裂缝等等。在实际工程中要区别对待，根据实际情况解决问题。 混凝土工程中常见裂缝及预防: 1.干缩裂缝及预防 干缩裂缝多出现在混凝土养护结束后的一段时间或是混凝土浇筑完毕后的一周左右。水泥浆中水分的蒸发会产生干缩，且这种收缩是不可逆的。干缩裂缝的产生主要是由于混凝土内外水分蒸发程度不同而导致变形不同的结果：混凝土受外部条件的影响，表面水分损失过快，变形较大，内部湿度变化较小变形较小，较大的表面干缩变形受到混凝土内部约束，产生较大拉应力而产生裂缝。相对湿度越低，水泥浆体干缩越大，干缩裂缝越易产 1原文出处及作者：《加拿大土木工程学报》