当前位置:考试网  > 试卷库  > 技能鉴定  > 安全生产  >  一般基坑开挖施工安全应注意哪些?
试题预览

一般基坑开挖施工安全应注意哪些?

查看答案
收藏
纠错
正确答案:

1.放坡开挖的基坑,其坡度应满足规范和设计要求。

2.坑壁不加固基坑施工,基坑平面尺寸一般应每边加宽 0.3 ~0.6m,如遇地下水,还应留出排水沟和集水井的位置,对于垂直开挖的无水基坑,可不加宽。

3、处在土石松动坡脚下的基坑,开挖前要做好防护工作;坑顶四周应做成反坡,并在距离坑缘适当的距离处设截水沟,防止雨水进入基坑;坑缘顶部如果有动载,动载与坑缘之间至少有 1m 宽的护道,地质水文条件不良时,护道要加宽或者采取加固措施;基坑弃土堆至坑缘的距离,要根据具体的地质条件来确定,但不得小于坑的深度。

4、严禁采用局部开挖深坑,从底部向四周掏土的方法施工。

5、人力出土时,要按照有关脚手架的规定,搭好出土走道,基坑较深时要搭设上下跳板或梯子;机械开挖时,要按照有关机械的操作规程和规定的信号,专人进行指挥;吊斗要拉溜绳;遇到涌水、涌沙、边缘坍塌等异常情况,人员要及时撤离,必须在采取了可靠的防护措施后才能继续施工。

6、基坑开挖要从速进行;在开挖阶段,如果出现地基面疏松要视情况夯实,或进行变更;当基坑开挖接近设计标高时,应注意预留 10~20cm,待下道工序准备就绪,在灌注前挖除;基坑开挖后要及时灌注或砌筑基础圬工,不得长期暴露或浸泡。

7、破碎的石质基坑,要根据岩石构造等情况决定开挖坡度;砂质土层或深度较大的基坑,要在边坡中段设 1m左右的护道;在开挖过程中要做好排水工作。

8、施工现场开挖沟槽边缘,与外电埋地电缆沟槽边缘之间的距离不得小于0.5m。在外电架空线路附近开控沟槽时,必须会同有关部门采取加固措施,防止外电架空线路电杆倾斜、悬倒。

9、坑壁支撑基坑施工,衬板可以紧密铺设或间隔铺设,一次挖成或分段挖成,但每次开挖不得超过 2m;如基坑较深时,四周应挂软梯,在开挖过程中发现异常情况,人员应及时撤离,加固后方可继续施工;支撑要选用质量良好的木材,在施工中要随时检查,并处理受力不均和应力集中等情况;在使用机械出土时,要防止碰撞支撑;在拆除支撑时,要自下而上分段进行。

10、采用钢筋混凝土围圈护壁时,除顶层可以一次整体灌注外,往下应根据土质情况,控制开挖高度和长度,并随开挖随灌注,其顶部应高出地面 0.5m,并挂好梯子,顶部不得摆放料具

答案解析:

暂无解析

你可能感兴趣的试题

掘进巷道必须采用压入式通风

称取氯化钡样品0.4801克,经重量法分析得 BaSO沉淀0.4578克,试计算样品中氯化钡的百分含量。( 注:=208.24;=217.39)

自燃事故属于责任事故的一种

用水扑灭电气设备火灾时,首先要切断电源

《烟花爆竹经营 (零售 )许可证》的有效期限为()年

热门试题 更多>
To begin with,"muzak"(音乐广播网 )was intended simplyto createasoothing(安慰)atmosphere.Recently,however,it's ecome big business —thanks in part to recentresearch.Dr.Ronald Milliman,an American marketing expert,hasshown that music can boost sales or increase factory roduction by as much as a third.But,it has to be light music.A fast one has no effect atall on sales.Slow music can increase receipts by 38%.This isprobably because shoppers slow down and have more opportunityto spot items they like to buy.Yet,slow music isn't alway sanswer.Dr.Milliman found,for example,that in restaurants slowmusic meant customers took longer to eat their meals,whichreduced overall sales.So restaurants owners might be welladvised to play up-tempo music to keep the customers moving—unless of course,the resulting indigestion leads tocomplaints! 练习: 1.The reason why background music is so popular isthat ______. A.it can have a powerful effect on those who hear it B.it can help to create a soothing atmosphere C.it can boost sales or increase factory production erywhere D.it can make customers eat their meals quickly 2.Background music means ________. A.light music that customers enjoy mostB.fast music that makes people move fast C.slow music that can make customers enjoy their meals D.the music you are listening to while you are doingomething 3.Restaurant owners complain about background musicbecause ______. A.it results in indigestion B.it increases their sales C.it keeps customers moving D.it decreases their sales 4.The word"up-tempo music"probably means_____. A.slow music B.fast music C.light music D.classical music
试题分类: 阅读
练习次数:4次
试题分类: 理论与实务
练习次数:0次
new weapon to fight cancer 1. British scientists are preparing to launch trials of a radical new way to fight cancer, which kills tumours by infecting them with viruses like the common cold. 2. If successful, virus therapy could eventually form a third pillar alongside radiotherapy and chemotherapy in the standard arsenal against cancer, while avoiding some of the debilitating side-effects. 3. Leonard Seymour, a professor of gene therapy at Oxford University, who has been working on the virus therapy with colleagues in London and the US, will lead the trials later this year. Cancer Research UK said yesterday that it was excited by the potential of Prof Seymour’s pioneering techniques. 4. One of the country’s leading geneticists, Prof Seymour has been working with viruses that kill cancer cells directly, while avoiding harm to healthy tissue. "In principle, you’ve got something which could be many times more effective than regular chemotherapy," he said. 5. Cancer-killing viruses exploit the fact that cancer cells suppress the body’s local immune system. "If a cancer doesn’t do that, the immune system wipes it out. If you can get a virus into a tumour, viruses find them a very good place to be because there’s no immune system to stop them replicating. You can regard it as the cancer’s Achilles’ heel." 6. Only a small amount of the virus needs to get to the cancer. "They replicate, you get a million copies in each cell and the cell bursts and they infect the tumour cells adjacent and repeat the process," said Prof Seymour. 7. Preliminary research on mice shows that the viruses work well on tumours resistant to standard cancer drugs. "It’s an interesting possibility that they may have an advantage in killing drug-resistant tumours, which could be quite different to anything we’ve had before." 8. Researchers have known for some time that viruses can kill tumour cells and some aspects of the work have already been published in scientific journals. American scientists have previously injected viruses directly into tumours but this technique will not work if the cancer is inaccessible or has spread throughout the body. 9. Prof Seymour’s innovative solution is to mask the virus from the body’s immune system, effectively allowing the viruses to do what chemotherapy drugs do - spread through the blood and reach tumours wherever they are. The big hurdle has always been to find a way to deliver viruses to tumours via the bloodstream without the body’s immune system destroying them on the way. 10. "What we’ve done is make chemical modifications to the virus to put a polymer coat around it - it’s a stealth virus when you inject it," he said. 11. After the stealth virus infects the tumour, it replicates, but the copies do not have the chemical modifications. If they escape from the tumour, the copies will be quickly recognised and mopped up by the body’s immune system. 12. The therapy would be especially useful for secondary cancers, called metastases, which sometimes spread around the body after the first tumour appears. "There’s an awful statistic of patients in the west ... with malignant cancers; 75% of them go on to die from metastases," said Prof Seymour. 13. Two viruses are likely to be examined in the first clinical trials: adenovirus, which normally causes a cold-like illness, and vaccinia, which causes cowpox and is also used in the vaccine against smallpox. For safety reasons, both will be disabled to make them less pathogenic in the trial, but Prof Seymour said he eventually hopes to use natural viruses. 14. The first trials will use uncoated adenovirus and vaccinia and will be delivered locally to liver tumours, in order to establish whether the treatment is safe in humans and what dose of virus will be needed. Several more years of trials will be needed, eventually also on the polymer-coated viruses, before the therapy can be considered for use in the NHS. Though the approach will be examined at first for cancers that do not respond to conventional treatments, Prof Seymour hopes that one day it might be applied to all cancers. Questions 1-6 Do the following statements agree with the information given in the reading passage? For questions 1-6 write TRUE if the statement agrees with the information FALSE if the statement contradicts the information NOT GIVEN if there is no information on this in the passage 1.Virus therapy, if successful, has an advantage in eliminating side-effects. 2.Cancer Research UK is quite hopeful about Professor Seymour’s work on the virus therapy. 3.Virus can kill cancer cells and stop them from growing again. 4.Cancer’s Achilles’ heel refers to the fact that virus may stay safely in a tumor and replicate. 5.To infect the cancer cells, a good deal of viruses should be injected into the tumor. 6.Researches on animals indicate that virus could be used as a new way to treat drug-resistant tumors. Question 7-9 Based on the reading passage, choose the appropriate letter from A-D for each answer. 7.Information about researches on viruses killing tumor cells can be found (A) on TV (B) in magazines (C) on internet (D) in newspapers 8.To treat tumors spreading out in body, researchers try to (A) change the body’ immune system (B) inject chemotherapy drugs into bloodstream. (C) increase the amount of injection (D) disguise the viruses on the way to tumors. 9.When the chemical modified virus in tumor replicates, the copies (A) will soon escape from the tumor and spread out. (B) will be wiped out by the body’s immune system. (C) will be immediately recognized by the researchers. (D) will eventually stop the tumor from spreading out. Questions 10-13 Complete the sentences below. Choose your answers from the list of words. You can only use each word once. NB There are more words in the list than spaces so you will not use them all. In the first clinical trials, scientists will try to ……10…… adenovirus and vaccinia, so both the viruses will be less pathogenic than the ……11…….These uncoated viruses will be applied directly to certain areas to confirm safety on human beings and the right ……12…… needed. The experiments will firstly be ……13……to the treatment of certain cancers
试题分类: 阅读
练习次数:2次
试题分类: 口语
练习次数:0次
扫一扫,手机做题