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Pressure relief

The early study of flared entrances was followed by studies of other types of tunnel extension regions and then by an assessment of the potential of airshafts to improve passenger comfort.  It was found that extended entrances are most suitable for non-crossing trains in short tunnels and that airshafts are especially effective for crossing trains.  Cross-connections between adjacent running tunnels can also be effective and, in long tunnels, they have the special advantage of reducing train power requirements. However, they pose special problems in the event of fire.

Validation

In early years, validation of the theoretical predictions was restricted to relatively simple cases that were available from full-scale measurements and from limited model-scale measurements. In 1977, however, Vardy was extremely fortunate to be asked to provide theoretical predictions for use with model-scale measurements to be obtained by Bain Dayman at the Jet Propulsion Laboratory.  Dayman’s experience in experimental processes at full-scale and model-scale ranged from developing supersonic wind tunnels to playing a leading role in the control of systems on Voyager space craft exploring the solar system. His tunnel measurements enabled the broad validity of an early version of ThermoTun to be demonstrated with high confidence for a wide range of tunnel and train geometries, including designs more complex than those likely to be implemented in practice.

Real train data

Having developed prediction methods of high accuracy, it became clear that the ability of designers to make full use of them was limited by inadequate knowledge of train properties.  This difficulty persists to the present day.  The amplitudes of pressure disturbances in tunnels depend strongly on the cross-sectional blockage effects of trains and upon their resistance characteristics.  The software assumes that questions such as “What is the cross-sectional area of the train?” have already been answered satisfactorily.  This is straightforward for smooth cylindrical “trains” used in model tests, but it is far from straightforward for real trains. Likewise, how can the resistance characteristics of the trains be deduced reliably, given that they are not the same as for trains travelling overland and that they are not even the same in different tunnels.  The required information can be obtained from full-scale tests, but it would not be plausible to propose this method for every train. Vardy has shown how reliable data can be inferred from measurements during routine operation and has attempted to derive parameters that are indicative of general types of train.

Sonic booms

The prediction of pressure fluctuations in railway tunnels is a relatively mature subject.  Nevertheless, one particular aspect remains a source of considerable uncertainty.  This is the likelihood of unacceptably large pressure disturbances radiating from tunnel portals.   In extreme cases, these disturbances can be experienced as loud sonic booms.  Much of Vardy’s research over the past two decades has been relevant to this topic.  It is one of the justifications for his long-standing interest in <unsteady skin friction> and it led to separate collaborative work with two Japanese Universities on passive and active methods of countering the problem through modifications to tunnel exit portals.  Nevertheless, the most reliable and cost effective ways of  overcoming the problem are (i) elongating train noses and (ii) providing special entrance regions for tunnels.  The latter brings us back full circle to Vardy’s original work at the University of Leeds in the early 1970s- although the motivation for that work was very different.

Учебное пособие

Черкасова Любовь Николаевна

Колесниченко Альвина Николаевна

АНГЛИЙСКИЙ ДЛЯ ИНЖЕНЕРОВ-СТРОИТЕЛЕЙ

(Промышленно-гражданское строительство)

Учебное пособие

Редактор А.В. Артамонов

Техническое редактирование и корректура А.В. Артамонова

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Адрес университета: 344038, г. Ростов н/Д, пл. им. Ростовского Стрелкового Полка Народного Ополчения, 2

Рецензия

на учебно-методическое пособие по английскому языку

для студентов, обучающихся по строительным специальностям

Черкасовой Л.Н., Колесниченко А.Н.

Учебно-методическое пособие содержит информационный материал по всем строительным специальностям. В нем приведены тексты, включающие богатый лексический материал по данным специальностям. Каждый текст сопровождается системой упражнений и вопросов, которые направлены на закрепление лексического, грамматического материала и развитие коммуникативных навыков.

Предназначено для студентов РГУПС, обучающихся на Строительном факультете по всем специальностям. Соответствует программе по английскому языку для второго курса. Отражает все темы, включенные в программу по английскому языку для строительного факультета.

Пособие может быть полезно в качестве дополнительного учебного пособия в ходе подготовки студентов и аспирантов к научно-исследовательской работе на иностранном языке.

Данное пособие соответствует требованиям, предъявляемым к рукописям, и может быть рекомендовано к печати.

К.ф.н., доц. М.Н. Черкасова

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