问题 问答题 论述题

分析库仑、莫尔、格里菲斯强度理论的基本观点并给予评价。

答案

参考答案:

库仑认为:岩石破坏为剪切破坏;岩石抵抗剪切破坏的能力由两部分组成:内聚力、内摩擦力。

莫尔认为:无论岩石处于何种应力状态,破坏均为剪切破坏;破坏时,剪切面上所需的剪应力不仅与岩石性质有关,而且与作用在剪切面上的正应力有关。

格里菲斯认为:不论岩石受力状态如何,最终在本质上都是拉伸应力引起岩石破坏。

评价:库仑强度理论是莫尔强度理论的直线形式。

莫尔理论较好解释了岩石抗拉强度远远低于抗压强度特征,解释了三向等拉时破坏,三向等压时不破坏现象,但忽视了中间应力的作用。

格式理论推导岩石抗压强度为抗拉强度的8倍,反映了岩石的真实情况,较好证明了岩石在任何应力状态下都是由于拉伸引起破坏,但对裂隙被压闭合抗剪强度增高解释不够。

莫尔理论适用于塑性岩石,及脆性岩石的剪切破坏;不适用于拉断破坏。

格式理论适用于脆性岩石及材料破坏。

阅读理解

阅读理解。

     Researchers found that walking around with a forced smile and fake (假的) happiness simply leads to

people feeling unhappier. So, putting a brave face on your sadness could be harmful. The research also

found that women suffered more than men when pretending to be happy.

     Dr. Brent Scott, who led the study, said employers should take note because forcing workers to smile when dealing with the public can result in bad outcomes. He said, "Smiling for the sake of smiling can lead

to emotional tiredness, and that's bad for the organization." He also said the research showed

customer-service workers who had "fake smiles" throughout the day fell into a bad mood and didn't want

to work, so their productivity dropped.

     The study is one of the first of its kind to examine emotional expressions over a period of time and

compare the different effects on men and women. Dr. Scott's team examined the effects of "surface

acting", or fake smiling, compared to "deep acting", or making people smile by thinking of peasant

memories.

     Dr. Scott said, "Women were harmed more by surface acting, meaning their moods worsened even

more than men's. However, they were helped more by deep acting, which means their moods improved

more by thinking of pleasant memories. "

     According to Dr. Scott, women tend to suffer more when pretending to be happy because they are

expected to be more emotionally expressive than men. Therefore, forcing a smile while feeling down is

more likely to go against their normal behavior and cause more harmful feelings.

     Although deep acting can improve moods a little in the short term, Dr. Scott says, it's not a long-term

solution to feeling unhappy. "There have been some suggestions that if you do this over a long period you

start to feel unreal. You're trying to develop positive emotions, but at the end of the day you may not feel

like yourself any more."

1. According to the passage, Dr. Scott's study ______.

A. is supported by some big employers in the USA

B. is meaningful as there haven't been many similar ones

C. examined more women than men for a long time

D. aimed to make the employees more productive

2. Women suffer more from fake happiness mainly because ______.

A. they usually turn up shy in public places

B. they should be more emotionally expressive

C. they are often treated in a terrible way

D. they like thinking of pleasant memories

3. It is implied in the passage that deep acting _____.

A. doesn't have any effect on men

B. cannot improve our moods in any case

C. harms our feelings in the long run

D. pleases people by feeling like another person

4. What is the best title for the passage?

A. Fake smiling makes people unhappy.

B. Women shouldn't be forced to smile.

C. An important suggestion for workers.

D. Why people don't want to work.

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