给排水工程外文翻译.docx

1、给排水工程外文翻译Short and Long Term Advantage roof drainage design performanceDecade 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 th

2、ese 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 an

3、d 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 drain

4、age 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

5、effectively design a variety of roof rainwater drainage system, and make it achieve the desired design effect.1. IntroductionIn 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 directio

6、n. 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 gradual

7、ly 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 fo

8、r 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 affec

9、ted 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

10、 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 r

11、educing 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

12、 of siphon system has not been well understood, resulting argument is relatively small, this article will highlight siphon system.2. RoofThe roof is usually designed by the architect, designer and not by the drainage design. There are three main roof.2.1 Flat roofFlat roofs are used in industrial bu

13、ildings 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 ma

14、intained 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 roofsMost residential and commercial buildings are pitched roof, inclined roof is the biggest advantage can quickly drain, thereby reducing leakag

15、e. 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

16、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 requirem

17、ents 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 Am

18、erica, 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 cultivatio

19、n 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 reduce

20、d 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

21、 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. Americas most authoritative green roof guidelines by the New Jersey state environmental agencies promulgated. The main principle is to solve

22、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

23、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 significan

24、t 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 dura

25、tion 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 CollectorBasic requirements rainwater collector is designed to be able to accommodate rainfall rainstorms. Although it is possible to ma

26、ke 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 outletAnalyzing rainwater

27、 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

28、 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 typ

29、e, 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

30、 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, be

31、cause 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

32、 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 classificationIn the complex flow sump outlet flow c

33、lassification, 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