问题 单项选择题

某饱和黏土层的厚度为8m,在土层表面大面积均布荷载力po=160kPa作用下固结,设该土层的初始孔隙比e=1.0,压缩系数a=0.3MPa-1。已知单面排水条件下加荷历时t=1年时的固结度Uz1=0.43。则该黏土层的最终固结沉降量以及单面排水条件下加荷历时一年的沉降量为()。

A.190mm,82.6mm

B.192mm,82.6mm

C.190mm,85.2mm

D.192mm,85.2mm

答案

参考答案:B

解析:

黏土层中附加应力σz沿深度是均布的,σz=q0=160kPa。

最终固结沉降量:

由题意知,在单面排水条件下,历时1年时的固结度Uz1=0.43。

则t=1年时的沉降量s1=Uz1s=0.43×192=82.6mm

点评:地基最终沉降量是指地基土层在荷载作用下,达到压缩稳定时地基表面的沉降量。常用的计算方法有分层总和法和《建筑地基基础设计规范》推荐的沉降计算公式。饱和土的压缩(固结)过程,包括土的孔隙中自由水的逐渐排出,孔隙体积的逐渐减小和孔隙水压力逐渐转移到土骨架来承受,成为有效应力三个方面。所以,饱和土的固结作用是排水、压缩和压力转移三者同时进行的一个过程。故饱和土的固结不仅与时间有关,而且还与排水条件有关。单向固结理论在饱和土的固结中应用很广,它是指土中的孔隙水只沿一个方向渗流,同时土颗粒也只有同一方向的位移。当荷载分布面积很广,靠近地表的薄层黏性土相当于单向固结情况。

阅读理解

Almost every child in cities has the chance to go to school, but not all children in the countries are so lucky.

There is a girl called Xiao Fang. She is eight years old and lives in a small village in Guangxi. When she was young, she wanted to go to school. But she could not, because her family was too poor to afford the school fees for her, so her parents had to keep her at home. Instead of studying, Xiao Fang worked in the fields with her parents every day. Then Project Hope heard about Xiao Fang. It agreed to help Xiao Fang to go to school. Her wish of study came true, and now she is studying in a school.

Unluckily there are many thousands of children who can not go to school. You can join in Project Hope and help these children. You know all the good work needs money. Project Hope needs your help.

If you give Project Hope¥300 each year, it can pay for one child to go to school for a whole year. With more money, Project Hope can build new schools, buy good desks, chairs, blackboards and books. Let’s help the children together and give them a chance to have a good start in life.

小题1:________________ can go to school.

A.Almost every child in the world

B.Almost every child in China

C.Almost every child in big cities

D.Almost every child in small villages小题2:Xiao Fang didn’t go to school when she was young because_________.

A.her family was too poor

B.she didn’t like to go to school

C.there was too much work for her to do

D.she could learn nothing at school小题3:With ¥300, _________.

A.one child can go to school for nine years

B.a new school can be built

C.many children can go to school

D.a child can go to school for a whole year小题4:Project Hope helped Xiao Fang because__________.

A.she went to ask for help

B.it heard about her

C.she knew someone working there

D.she wrote a letter to the newspaper小题5:Which of the following is TRUE?

A.Project Hope helps the poor children to go to school.

B.Project Hope helps to build new schools.

C.Project Hope helps schools to buy desks, chairs, books, etc.

D.All the above.

多项选择题