问题 问答题 简答题

影响采煤工作面煤壁片帮的因素有哪些?

答案

参考答案:

影响采煤工作面煤壁片帮的因素主要有:

(1)煤层节理裂隙等弱面分布及地质破碎带。

(2)煤壁处的支承压力。当受上部煤层的煤柱影响或在老顶来压期间都能引起支承压力增高,进而煤壁片帮面为松塌区,支承压力再向煤体深转移,支承压力愈高,松塌区愈宽。

(3)采高,松塌区煤壁的片帮深度随着采高的增加而扩大。

(4)工作面管理及操作不当,如支架初撑力和工作阻力过低使支架不能有效接顶,移架不及时,或移架时降柱过多;未发挥护帮板作用,工作面工程质量差,支架挤、倒或架间距过大,移不动仍盲目降柱,设备故障多,推进速度慢等。

阅读理解

阅读理解。

      More and more often we heard of people talking about Karaoke (卡拉OK). But what on earth it is about,

still remains a question for many people. Karaoke is a sort of acoustic equipment which was invented in Japan

around the middle of the 1970's. It means "a band without people" in Japanese. In fact, it is just a music tape

without words. This equipment first appeared in some public houses and snack bars, and mainly for the

customers to enjoy themselves. Most of the music in Karaoke was popular music. Therefore, at times, when

anyone felt like it, he might sing songs to the accompaniment of the music that came from the equipment.

Shortly after its invention, Karaoke was spread to the whole world. It was introduced to China and was

welcomed by many people. Although you are not a good singer, or even sometimes you may sing out of tune,

you can always enjoy yourself by singing Karaoke.

1. In this passage "band" means "group of persons _____." [ ]

A. who play games on the sports ground

B. who play music together

C. living in the same neighborhood

D. doing things together under a leader and with a common purpose

2. Karaoke is just a _____. [ ]

A. cassette tape with only music

B. cassette tape recorder

C. band from Japan

D. voice recording equipment

3. Karaoke was spread to the whole world _____. [ ]

A. as soon as it was invented

B. long before

C. not long after it was invented

D. before long

4. The main idea of this passage is _____. [ ]

A. all persons like to play Karaoke

B. to introduce Karaoke to the people

C. Karaoke is a wonderful equipment

D. Karaoke is used everywhere including snack bars

多项选择题