56. Translate the following phrases into English.

Основные структурные компоненты, свободная каменная наброска, выдерживать нагрузку, десять метров в диаметре, получать ровную поверхность, построенный из бетона, монолит без деформационных швов, горизонтальное и вертикальное направления, подвергаться значительной осадки, основной недостаток плотины, во многих случаях, регулярный ремонт мембраны, более строгие требования к основанию, доступный строительный материал, уменьшать утечку, заделывать швы эмульсией, из-за узкой ширины основания,

57. Find the translation of the following terms and memorize them.

a single wall sheet-pile type		miscellaneous
cypress	cellular cofferdam	a crib dam
cofferdam	commonly	to bolt
to divert	circular	redwood
watertight	sheet-pile cells	crib
a pile	to tend	cedar
earth fill	mixture	shallow

58. Read the text to get the gist of it. Answer the following questions.

Are cofferdams permanent or temporary structures?

What timbers are the most durable?

Text F Miscellaneous Types of Dams

A timber crib dam is made of timber bolted into cribs and filled with rock. The life of a timber dam varies from 10 to 40 years depending upon climatic conditions and the type of timber used. Cedar, redwood and cypress are the most durable timbers. Where there is an adequate supply of timber, crib dams are quite inexpensive and generally satisfactory for heights not exceeding about 20 ft.

Cofferdams are temporary structures used to divert water from an area where the construction operations are to be conducted. A cofferdam must be relatively low in cost but as watertight as possible. The simplest kind of cofferdam is a single wall sheet-pile type, sometimes strengthened by an earth fill on both sides. A single wall sheet-pile cofferdam can be used only in very shallow water. For depths over about 5 ft cellular cofferdams are commonly used. These consist of circular sheet-pile cells filled with earth. A mixture of sand and clay is the best filler since clay itself tends to wash out through the gaps between the piles while sand is too permeable. Timber-crib dams are sometimes used as cofferdams. The simplest embankment often requires too much room because of the large base width necessary for an embankment of any height.

59. Decide whether the following statements are true or false according to the text.

1. A timber crib dam is made of timber bolted into cribs and filled with earth.

2. The life of timber dam is limited to 10 years.

3. Cedar, redwood, cypress are the most permanent timbers.

4. A cofferdam must be relatively low in cost but as hermetic as possible.

5. For depths over about 5 ft sheet-pile dam are commonly used.

6. A mixture of clay and sand is the worst filler.

7. The simplest embankment often requires too much place because of the large base width.