问题 问答题

背景资料
某某沿海大桥,其主墩基础有40根桩径为1.55m的钻孔灌注桩,实际成孔深度达50m。桥位区地质为:表层为5m的砾石,以下为37m的卵漂石层,在以下为软岩层。承包商采用下列施工方法进行施工:
场地平整,桩位放样,埋设护筒之后,采用冲击钻进行钻孔。然后设立钢筋骨架,在钢筋笼制作时,采用搭接焊接,当钢筋笼下放后,发现孔底沉淀量超标,但超标量较小,施工人员采用空压机风管进行扰动,使孔底残留沉渣处于悬浮状态。之后,安装导管,导管底口距孔底的距离为35cm,且导管口处于沉淀的淤泥渣之上,对导管进行接头抗拉试验,并用1.5倍的孔内水深压力的水压进行水密承压试验,试验合理后,进行混凝土灌注,混凝土坍落度18cm,混凝土灌注在整个过程中均连续均匀进行。
施工单位考虑到灌注时间较长,在混凝土中加入缓凝剂。首批混凝土灌注后埋置导管的深度为1.2m,在随后的灌注过程中,导管的埋置深度为3m。当灌注混凝土进行到10m时,出现坍孔,此时,施工人员立即用吸泥机进行清理;当灌注混凝土进行到23m时,发现导管埋管,但堵塞长度较短,施工人员采取用型钢插入导管的方法疏通导管;当灌注到27m时,导管挂在钢筋骨架上,施工人员采取了强制提升的方法;进行到32m时,又一次堵塞导管,施工人员在导管始终处于混凝土中的状态下,拔抽抖动导管,之后继续灌注混凝土,直到顺利完成。养生一段时间后发现有断桩事故。
问题:

钻孔的方法有哪些?

答案

参考答案:

解析:冲击法,冲抓法,旋转法。

单项选择题 A1/A2型题
单项选择题

The questions in this group are based on the content of a passage. After reading the passage, choose the best answer to each question, Answer all questions following the passage on the basis of what is stated or implied in the passage.

Forget hostile aliens. According to a forthcoming book by noted astrophysicist Egbert Larson, the intrepid humans who first attempt interstellar space travel will face far more daunting challenges before they ever meet the Little Green Men.

Larson begins with the problem of relativistic time dilation. If you travel all the way to Alpha Centauri, you’d like to come back and tell your friends about it, right It’s not too likely to happen, though. If Mr. Einstein was right about relativity--and we’re not going to say he wasn’t--then time slows down when you approach the speed of light. A person traveling at any velocity near the speed of light will age only days for every week, month, or even year that passes on earth. Relativity does not present a problem for interstellar space travel, per se, but it does mean that interstellar civilizations or even just interstellar communications will require a mind-boggling amount of calendar juggling.

Did we mention that you’d have to travel at near the speed of light That’s because the distance between stars is so vast that even if you could travel at the speed of light--which, Larson reminds us, you can’t--it would take more than four years to reach our closest star neighbors, Alpha Proxima and Alpha Centauri, and decades or centuries to reach the other stars in our "immediate neighborhood." And if you tried to accelerate directly to the speed of light like they do in the movies, you’d be instantly splattered on the back of your theoretical spacecraft. Achieving anything close to light speed will require sustained accelera- tion at a level that human bodies can withstand--say, a crushing two gravities--for over a year. Better hope somebody brings some chips.

Speaking of chips, food is going to be a problem. Since it is economically, if not physically, impossible to accelerate 200 years’ worth of food to nearly the speed of light, and since you’re not likely to find any grocery stores along the way, someone will have to figure out how to make food in space. Keeping a crew alive on the way turns out to be the trickiest part of all. Once you’ve got the nearly impossible physics of space travel worked out, you still have to figure out the chemistry and biology of keeping your air and water clean and keeping your crew fed and safe from radiation and infection, and--did we mention the 200 years--you’ll probably need several generations of crew members to complete the trip. Ever been on a bus for more than 24 hours It’s not a pretty picture.

We applaud Larson for his insightful writing and his scrupulous attention to scientific detail. For those of you seeking a cold, hard look at the reality of interstellar space travel, this is a stellar read. But be warned: Larson doesn’t let you down gently. For those of you sincerely hoping to beam up with Scotty--and you know who you are--you might want to give this one a pass.

Based on the tone and content of the passage, it is most likely which of the following ?()

A. A book review in a journal intended for astrophysics professionals

B. A movie review in an entertainment industry publication

C. A book review in a science magazine aimed at a general audience

D. A book review in a newspaper

E. A transcript of a talk given at a science fiction convention dedicated to "the poetry of space\