问题 问答题 简答题

松散砂土产生液化的机理是什么?防止砂土液化的主要方法是什么?

答案

参考答案:

在振动(如地震)作用下,松散砂土将产生液化,液化的原因在于砂土受到振动后趋于密实,导致土体中孔隙水压力骤然上升,相应土粒间的有效应力减小,从而降低了土的强度。在周期性的振动荷载作用下,孔隙水压力逐渐累积,甚至可以抵消有效应力,使得土粒处于悬浮状态。此时土体完全失去抗剪强度而显示出近于液体的特性,这种现象就称为液化。防止砂土产生液化的主要方法是改良土质,增加砂土的密实度。施加动荷载是增加砂土密实度的有效方法。

阅读理解

阅读理解

     The teacher who did the most to encourage me was, as it happens, my aunt.She was Myrtle C.

Manigault, the wife of my mother's brother Bill.She taught me in second grade at allblack Sumner

School in Camden, New Jersey.

     During my childhood and youth, Aunt Myrtle encouraged me to develop every aspect of my

potential, without regard for what was considered practical or possible for black females.I liked to

sing; she listened to my voice and pronounced it good.I couldn't dance; she taught me the basic

dancing steps.She took me to the theatre-not just children's theatre but adult comedies and

dramas-and her faith that I could appreciate adult plays was not disappointed.

     My aunt also took down books from her extensive library and shared them with me.I had books

at home, but they were all serious classics.Even as a child I had a strong liking for humour, and I'll

never forget the joy of discovering Don Marquis's Archy & Mehitabel through her.

      Most important, perhaps, Aunt Myrtle provided my first opportunity to write for publication.A

writer herself for one of the black newspapers, she suggested my name to the editor as a "youth

columnist". My column, begun when I was fourteen, was supposed to cover teenage social

activities-and it did-but it also gave me the freedom to write on many other subjects as well as the habit

of gathering material, the discipline of meeting deadlines, and, after graduation from college six years

later, a solid collection of published material that carried my name and was my passport to a series of

writing jobs.

     Today Aunt Myrtle is still an enthusiastic supporter of her "favourite niece". Like a diamond, she has

reflected a bright, multifaceted (多面的) image of possibilities to every pupil who has crossed her path.

1. Which of the following did Aunt Myrtle do to the author during her childhood and youth?

A. She lent her some serious classics.

B. She cultivated her taste for music.

C. She discovered her talent for dancing.

D. She introduced her to adult plays.

2. What does Archy & Mehitabel in Paragraph 3 probably refer to?

A. A book of great fun.  

B. A writer of high fame.

C. A serious masterpiece.  

D. A heartbreaking play.

3. Aunt Myrtle recommended the author to a newspaper editor mainly to ________.

A. develop her capabilities for writing

B. give her a chance to collect material

C. involve her in teenage social activities

D. offer her a series of writing jobs

4. We can conclude from the passage that Aunt Myrtle was a teacher who ________.

A. trained pupils to be diligent and welldisciplined

B. gave pupils confidence in exploiting their potential

C. emphasized what was practical or possible for pupils

D. helped pupils overcome difficulties in learning

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