Предтекстовые упражнения

1. Вспомните значения следующих слов, знакомых из пре­ дыдущих текстов.

accommodation, harbour, to rank among, claim attention, shore, mostly, withstand, thoroughly, facilitate, excavation, pump out, float, removal, demand for, volume, urgent, pollu­tion, leakage.

2. Вспомните, какие русские слова имеют те же корни, что и следующие английские слова:

phenomenon, prevailing, combination, dock, constant, to function, selection, gigantic, tonnage, corrosion, cathodic, permanent, gravity.

К каким из вышеприведенных слов русскими эквивален­тами являются слова: явление, сочетание, выбор, долговеч­ный (постоянный)?

3. Прочтите текст. Определите, какие сооружения порта обеспечивают возможность ремонта судов.

Text. On Marine Structures

1. To create a quiet port basin and provide safe accommo­ dation for the ships the harbour should be protected from the wind and wave actions by special engineering works if shel­ tering has not been provided by nature.

2. As marine structures Yank among the most expensive the demands for safety and economy of the engineering works are especially high. Meteorological phenomena—winds, fre­ quency of storms, the height and force of waves, etc. claim special attention of the designer of protective structures, such as breakwaters. As the name implies, they serve to break the waves and reduce their force and effect on the port basin. They are built away from the shore on the side of the port mostly affected by prevailing winds and waves. Breakwaters are to withstand great loads and stresses and the character of the sea bottom which takes the final reaction of these stresses should be studied no less thoroughly. Being gravity structures breakwaters depend for their stability upon their weight. Natural rock and concrete or a combination of both are the materials which form 95 per cent or more of all breakwaters constructed.

3. Any important port cannot do without docks of which there are three main types depending on the designation. They are: harbour docks, repair or dry docks and shipbuilding docks. The harbour docks are particularly useful in harbours with a considerable water level change due to tides. It is so arranged that the water inside may be kept at a more or less constant level to facilitate loading and unloading of cargoes. Repair docks are basins usually made by excavation, having entrance- ways closed with gates. After the ship is floated in, the gates are closed, the water is pumped out and the ship settles or. the blocks specially provided for the purpose. Another type of this structure is a floating dock serving the same purpose but functioning on a different principle. It is submerged by letting water into its interior and the ship is floated into position. The removal of the water from the dock by pumping raises the structure with the ship within. Both the docks have their advantages and the selection of the type of structure fully depends on local conditions and requirements.

4. When discussing port structures mention should be made of coal and oil jetties—special berths situated apart, for reasons of convenience and fire prevention. They either have storage tanks or are equipped with pipelines leading to storage tanks on the shore. Demands for oil increase e\ery year and to cope with the problem of moving large volumes of oil around the world, gigantic tankers have been developed. To accommodate tankers of, say, 312 000 ton deadweight oil ports are becoming correspondingly larger and the need for effective oil pollution control has become ever more urgent.

5. Two obvious steps to be taken to solve the problem of oil pollution are: prevention of oil leakage from tankers and oil storage tanks and second—the containing or removal of oil when spillage occurs. At present there is no single technique whereby oil spillage can be completely controlled, but some methods have been developed of retaining oil polluted water in a confined area. Research is being continued as the tonnage of oil and its products is nearly equal to the combined tonnage of all other cargoes in ocean trade.

6. As to the materials used for marine structures concrete of prestressed and precast kinds plays the leading role. Im­ proved protective coatings against corrosion for concrete and steel have enabled much lighter and more economical types of construction to replace the heavy masonry. The use of cathod- ic protection helps to make steel below the water level reas­ onably permanent.