Деловой английский язык. Енютина А.А. - 25 стр.

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detonation, an explosive suddenly releases an enormous amount of heat and
pressurized gases, which expand rapidly and powerfully in the rock. The explo-
sive energy leads not only to rock fragmentation and to displacement, but also
produces ground vibration and air blast.
      Surface blasting in quarries offer sufficient free space for the blast to ex-
pand freely and the drilling patterns are therefore not very complicated. Blasting
typically advances in more or less straight rows. In underground drifting, only
one free surface is normally available for the blasted rock to expand. This means
that the blast must be strong enough to throw the rock forward, sufficiently well
controlled to prevent any excessive cracking and breaking of the surrounding
rocks. Special explosives are often used to ensure the smooth blasting of holes
closest to the walls and roof. Shaft sinking and traditional raise driving are spe-
cial and even more restricted cases of blasting.
      The explosives used in underground excavation must be easy to store, safe
and non-toxic as possible. Blasting is often performed immediately or within
a couple of hours of the holes being charged, so the explosives, which are left in
holes, must still be effective, water resistant and stable.

                                     Задания

       1. Переведите текст на русский язык.
       2. Ответьте на вопросы к тексту:
       a) What is explosive?
       b) What are the requirements to the explosives, used in underground blast-
ing?
     c) Why is not drilling pattern for surface blasting very complicated?
     3. Переведите на английский язык следующие предложения:
     a) Кроме смещения породы и раздробления ее на куски, взрывание
производит вибрацию грунта и взрывную волну.
     b) Подземное взрывание должно тщательно контролироваться, чтобы
предотвратить чрезмерное растрескивание и разрушение окружающей по-
роды.
     c) При подземных взрывных работах необходима хорошая вентиляция
для удаления токсичного дыма.