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发表于 2006-10-12 18:30:09
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找到1篇论文和另外一篇论文的摘要，关于有道渣和无道渣的优劣比较以及适合使用范围。
第一篇是Pandrol公司的技术指导，全文大部分如下
Slab track evolves to meet operators' expectations
by David Rhodes, Director - Technical Development, Pandrol Limited
Reprinted from Railway Gazette International
........... Several major projects, including the Taipei - Kaohsiung high speed line in Taiwan, HSL-Zuid in the Netherlands, and the second phase of Britain's Channel Tunnel Rail Link will incorporate substantial lengths of non-ballasted track.
Despite the high initial costs, non-ballasted track forms have a significant advantage in requiring little or no maintenance to retain a high quality of geometry over many years. As railway engineers gain a better understanding of the life-cycle costs, they are able to assess more objectively the potential benefits of non-ballasted against ballasted trackwork. Conventional ballasted track is still used in almost all new construction, because it does have some significant advantages. In particular, the ballast provides a means of adjusting track geometry, during both construction and maintenance operations, and it provides a degree of elasticity in the track structure.
The key to a successful slab track design is providing elasticity and adjustability in a practical and economical way, despite the inherently rigid nature of the concrete slab.
pThe most widely used form of slab track for high speed lines uses prefabricated, pre-stressed units, typically 5m long, laid on a slip-formed base slab with a cement-asphalt mortar interface layer.p
pAlmost all Japanese and Italian high speed lines built since the early 1980's have used this technique. It allows for most of the adjustment that is required when the track is being built, and provides some flexibility in the interface between the pre-cast unit and the concrete poured in situ. With this type of track, sufficient extra resilience can be obtained with a conventional rail pad. In tunnels, only a small amount of maintenance adjustment is required, and this can be achieved with minor modifications to the rail fastenings. On elevated structures especially in the seismically-active areas where the design is most used, it is usual to mount the rail fastening on a baseplate, which provides almost unlimited vertical and lateral adjustment possibilities (Figure 1).
Figure 1 - Where the Japanese shinkansen run through seismically-active areas, a baseplate-mounted rail fastening allows almost unlimited adjustment
Another design, used on high speed, conventional main line and urban railways, makes use of twin-block sleepers or sleeper blocks set into rubber 'boots' recessed into the base slab. This provides additional elasticity, and makes it possible to use a standard concrete sleeper rail fastening. When used on high speed track, some additional adjustability may be needed in the rail fastenings. Most French high speed lines use conventional ballasted track, but where non-ballasted track is used, such as in long tunnels, this has been the preferred system. Other applications include the Channel Tunnel and the Oresund Link (Figure 2).
Figure 2 - The Oresund link tunnel uses a trackform with twin-block sleepers recessed into a base slab.
This results in a rigid interface between the pre-cast units and the in situ concrete. The interface can fail when subjected to impact loads, and is vulnerable to damage by water ingress. Various ideas have been tried to overcome these problems, including treatment of the pre-cast concrete surfaces and the use of very elastic fastenings (Figure 3). These techniques have been used to provide very effective slab track designs for transit systems, but the proliferation of Rheda track design variants in Germany is an indication of the inherent difficulties encountered in making this design work on high speed lines.
Vibration
Where railways - whether Metros or high speed lines - run on slab track in urban areas, it may be necessary to consider the impact of environmental noise and vibration. With conventional track, the ballast helps to reduce vibration transmission and absorb airborne noise. With concrete track, extra mitigation measures may be needed to compensate for the absence of ballast. This typically requires low-stiffness supports under the rail (Figure 4). The elasticity that can be provided is limited by the amount of rail 'roll' and hence dynamic gauge widening, that can be accepted on curves. Metro networks typically set this limit between 4mm and 7mm, but high speed lines may have much tighter tolerances.
Figure 5 - Non-conventional rail fastenings, which support the head rather than the foot of the rail, can help to prevent the transmission of very low frequency vibration. In general, slab tracks require a low frequency dynamic stiffness of 50 to 100 MN/m to ensure good structural performance (or about 30 MN/m for Rheda systems), but less than 20 MN/m for effective environmental vibration isolation. .................
Non ballasted tracks are here to stay. The challenge to track designers is to make such tracks economical to build, environmentally acceptable, and true to the operators' expectations of minimal long-term maintenance requirements.
第二篇是荷兰代尔夫特大学教授写的论文的摘要。
Coenraad EsveldProfessor of Railway Engineering, TU Delft
The major advantages of slab track are: low maintenance, highavailability, low structure height, and low weight. In addition, recent life cycle studies have shown, that from the cost point of view, slab tracks might be very competitive（强调，从长期维护开销算，无道渣轨道可能会更有竞争力）.Experiences in high-speed operation have revealed that ballasted tracks are more maintenance intensive. Inparticular, due to churning up of ballast particles at high-speed, serious damage can occur to wheels and rails,which is of course prevented in the case of slab track.In the paper various non-ballasted concepts are discussed and some considerations are made in relation to lifecycle cost for high-speed track
很清楚可以看到，无道渣轨道的最重要的优势是 维护需求非常小，但在技术方面和有道渣相比，没有什么优势。
相比有道渣轨道
无道渣轨道优势是：维护小，甚至一段时间内免维护，长远投资可能划算。
其他优势........有些找茬，并不狠重要，比如提到的建筑结构高度低一些，重量轻一些，不会把小石头卷起来砸到花花草草..............
无道渣轨道劣势是：前期投入很高
灵活度非常小，相关调教必须在建设期间完成，只在关键链接处提供有限调整并花费很大。
而有道渣轨道建成后改造和调整非常方便，灵活度很大，风险小。
容易受到渗水和进水破坏，链接点容易被负载破坏。
噪音大
容易在一定频率下引起共振，不能吸收震动。
文中提到了目前无道渣轨道应用例子，主要适合使用在维护困难的地方，最明显的例子就是隧道还有多桥梁的地方。其他多数地方，仍适合使用有道渣轨道。根本不是无道渣更适合跑高速...............文中举例说明，法国绝大多数是有道渣，只在隧道中使用无道渣。德国最新的高速铁路仍然是有道渣轨道，目前德国无道渣轨道技术存在"与生具来"（文中原话）的难度将其使用在高速铁路上。（日本无道渣轨道使用狠广泛，不知道是不是日本比较有心得）
此外，中标西安－－郑州高铁无道渣技术设备提供者，德国Züblin公司也提到，未来15年，全球有12000公里高铁建设需求，其中1/3需要无道渣轨道。要注意，这是一个靠无道渣吃饭的，极力推崇无道渣技术的公司，但即使是他们仍然认为只有部分铁路需要无道渣轨道，这足以说明问题了。至少秦沈将来在有道渣基础上改300没有问题，反而因为多平原，并且国内劳动力廉价，维护费用大大降低，使用有道渣更好，更何况适合使用的部分桥梁，秦沈使用的正是硬连接，无道渣技术。
[ 本帖最后由 herroyuy 于 2006-10-12 19:07 编辑 ] |
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