问题 问答题 简答题

修建高速公路可能有哪些环境地质问题,如何防治?

答案

参考答案:

(1)截断含水层

(2)地下水位下降

(3)边坡稳定性的破坏

(4)淤积和侵蚀作用

(5)排出酸性水体,如果沿公路出露含有黄铁矿和其他硫化物,尤其容易受到风化与淋滤作用损害,正如在露天矿采煤一样,能产生富含硫酸的水

(6)人为污染物的影响,供水水源附近地带与植被的地带最易受到汽车废气的污染

防治:

(1)在设计中,要对路线走向,控制地点,沿线地形地貌地物、地质条件有充分的认识和了解,尽量避免路线经过可能崩滑流地段

(2)对无法避免的特殊地质条件或不良地质环境进行改造,如对岩质高边进行固化等

(3)在施工和运输中尽量减少对自然地质环境的破坏

单项选择题
单项选择题

The fact that most Americans live in urban areas does not mean that they reside in the center of large cities. In fact, more Americans live in the suburbs of large metropolitan areas than in the cities themselves.
The Bureau of the Census regards any area with more than 2,500 people as an urban area, and does not consider boundaries of cities and suburbs.
According to the Bureau, the political boundaries are less significant than the social and economic relationships and the transportation and communication systems that integrate a locale. The term used by the Bureau for an integrated metropolis is an MSA, which stands for Metropolitan Statistical Area. In general, an MSA is any area that contains a city and its surrounding suburbs and has a total population of 50,000 or more.
At the present time, the Bureau reports more than 280 MSAs, which together account for 75 percent of the US population. In addition, the Bureau recognizes 18 megapolises, that is, continuous adjacent metropolitan areas. One of the most obvious megapolises includes a chain of hundreds of cities and suburbs across 10 states on the East Coast from Massachusetts to Virginia, including Boston, New York, and Washington, D.C. In the Eastern Corridor, as it is called, a population of 45 million inhabitants is concentrated. Another megapolis that is growing rapidly is the California coast from San Francisco through Los Angeles to San Diego.

Why does the author mention the Eastern Corridor and the California coast in Paragraph 4

A. As examples of megapolises.
B. Because 75 percent of the population lives there.
C. To conclude the passage.
D. The Bureau of the Census is located there.