土木工程专业英语unit4(3)课件.ppt

1、 Unit 4 Soil Improvement 地基处理地基处理Learning Guidance Master:The reasons and purposes of soil improvement;the methods of soil improvement 掌握：地基处理的原因和目的；地基加固的方法 Teaching Important Point:the methods of soil improvement(地基加固的方法)Teaching Diffcult Point:Methods:压实法(Compaction)预压法(Preloading)排水法(Drainage)灌浆法

2、(Grouting)振冲法(Vibroflotation)New Words and Phrases 1.replacement n.置换 paction n.压实 3.preload n.预压 4.drainage n.排水 5.backfill v./n.回填 6.granular adj.颗粒的；粒状的 7.watertight adj.水密的；不漏水的 8.precompression n.预压缩 9.permeability n.渗透性 10.cement n.水泥；接合剂 11.centrifugal adj.离心的 n.离心机v.巩固/加强synonym:consolidate/

3、solidify/enhance/intensify/strengthenPhrases 12.soil improvement 地基处理 13.shear strength 抗剪强度 14.impact vibration 冲击振动 15.water table 地下水位 16.void ratio 孔隙比 17.hydraulic gradient 水力梯度 18.sand drain 砂井；排水砂桩 19.consolidating stratum 固结土层 20.mandrel-driven pipes 套管法 21.driven pipes 打入管法 22.rotary drill

4、回转钻进法 23.continuous-flight hollow auger 空心螺旋钻法 24.wick drain 排水芯板 25.textile filter blanket 织物滤水垫层 26.horizontal trench drain 水平排水沟槽 27.jet grouting 旋喷灌浆法 28.vibroflotation 振冲法 29.soil excavation 土体开挖 30.in advance of 超过；在的前面 31.in combination with 与相结合；与联合Introduction楼倒倒楼倒倒楼歪歪楼歪歪Part I Soil Improve

5、mentIntroduction：Geotechnical considerations will primarily be on strength and deformation and those soilwater phenomena that affect strength and deformation.土体的强度和变形以及土中水对强度和变形的影响是土木工程的基本问题。With the current trend to using sites with marginal soil parameters for major projects,methods to improve the

6、 strength and deformation characteristics through soil improvement will be briefly considered in this chapter.目前的趋势是将大型工程建在土体性质较差的场地之上（因为好的场地已所剩无几），因此本章将会简要介绍通过地基加固来提高土体强度和变形特性的方法。The centuries-old problem of land scarcity in the vicinity(临近、附近临近、附近)of existing urban areas often necessitates the use

7、 of sites with soils of marginal quality.数个世纪以来现有城区附近土地缺乏的老问题经常使得必须利数个世纪以来现有城区附近土地缺乏的老问题经常使得必须利用具有不良土层的场地。用具有不良土层的场地。In many cases these sites can be utilized for the proposed project by using some kind of soil improvement.在许多情况下，这些场地需要地基加固后才能用于拟建工程。在许多情况下，这些场地需要地基加固后才能用于拟建工程。marginal lands：贫瘠的土地 ma

8、rginal seat：边缘席位marginal improvement：略有增长a marginal standard of living：最低限度的 生活水平 The purpose of soil improvement is to improve the performance of the ground by using of the techniques,such as replacement,compaction,preloading and drainage etc.地基处理的目的是通过使用置换、压实、预压和排水等各种方法对地基进行加固，以改良土的特性。Here，we will

9、 focus on several of the more widely used methods of improving soils for bearing capacity.在此，我们着重介绍广泛用于提高地基承载力的几种地基加固方法。concentrate onpay attention toemphasizeAn extremely large number of methods have been used and/or reported in the literaturemany of which have been patentedand at an individual sit

10、e one may use a mix of several methods to achieve the desired result.已有大量的地基加固方法被使用过且（或）在相关文献中报道过，其中的许多方法也已经申请了专利。而对于一个具体的场地，可采用数种方法相结合以达到预期的效果。n.national patent 国家专利 patent law 专利法，专利权法 patent application 专利申请书 patent protection 专利保护 product patent 产品专利权 patent holder 专利持有方adj.显然的（obvious/evident/a

11、pparent）v.授予专利/取得.专利Compaction Compaction(压实法)is usually an economical method of improving the bearing capacity(地基承载力)of site soils.压实法一般是一种提高场地地基承载力成本较低的方法。It may be accomplished by excavating(挖掘)to some depth,then carefully backfilling in controlled lift thicknesses,(each of which)is compacted wit

12、h the appropriate compaction equipment.它的做法是先下挖至一定深度，然后按控制的填筑层厚仔细回填，并对每一填筑层采用适当的压实设备压实。This method is usually the most economical means to achieve particle packing for both cohesionless and cohesive soils and usually uses some kind of rolling equipment.对于无黏性土和黏性土，这种方法是使得土粒排列密实的最为经济的方法，它一般需要采用某种碾压装置。

13、Dynamic compaction(强夯)is a special type of compaction consisting of(由.组成)dropping heavy weights on the soil.“强夯”是将重锤由高空落向地基土体的一种特殊压实方法。14 4.4.soil improvementn Although the dropping of a weight on the soil had probably been in use for centuries,it was reintroduced to the profession and patented by L

14、.Menard in France ca.1970.n尽管使重物落向地面的方法或许已被使用了几个世纪之久，但是约在1970年法国工程师L.Menard才将其从专业角度重新引入并取得专利。nCompaction can be achieved to a substantial depth depending on weight(or mass)of the tamper,height of fall,and the type of soil.n相当大深度内的土体可得到夯实，强夯的加固深度与夯锤的重量（或质量）、落距以及土的类型有关。tamper:n.夯具v.篡改(distort)损害/削弱(ha

15、rm/damage/injure)贿赂(bribe/corrupt)15 Although the dynamic compaction tamper can have a mass up to 150,000 kg(or 150 tons),the usual mass is on the order of 10 to 20 tons and is dropped from heights ranging up to 40 m(usually 10 to 20 m)onto a grid spacing so that the site requiring improvement is ad

16、equately covered.虽然在强夯法中夯锤的质量可达虽然在强夯法中夯锤的质量可达150000kg150000kg（或（或150t150t），但在一般情况下其），但在一般情况下其质量约为质量约为101020t20t，夯锤从最高可达，夯锤从最高可达40m40m（一般为（一般为101020m20m）的高度落下，夯）的高度落下，夯点的布置形式可采用网格状，使之充分覆盖需要加固的场地。点的布置形式可采用网格状，使之充分覆盖需要加固的场地。Craters ranging from 0.5 to 2 m in depth are produced at the points of impact.在

17、夯点处可产生深为0.52m的夯坑。After a selected part of the area to be compacted is covered by a pass(drop in each grid point)it is graded with a bulldozer(推土机)using imported fill as necessary to smooth the surface,the next pass is made,and so on until the desired density is obtained.Density is usually specified

18、based on before and after penetration tests(either SPT or CPT).当需要夯实的区域被夯击一遍后（夯点为网格上的每一个交点），采用推土机来平土方（如有必要还应运入新土以整平场地表面），然后进行下一遍夯击，如此重复直至达到预期的密实度。密实度一般可根据夯击前后的触探试验（SPT或CPT）来确定。Penetration tests:触探试验，它是一种常用的原位测试技术。由于其设备简单、易于操作、使用效率高而应用较为广泛。实验方法包括动力触探动力触探（DPT:Dynamic penetration test）、标准贯入标准贯入（SPT:Sta

19、ndard penetration test）和 静力触探静力触探（CPT:Cone penetration test）三类 After the site improvement is completed,the area is brought to grade and compacted with ordinary compaction equipment.在对整个场地采用强夯加固完毕后，应对场地进行整平并采用常规的压实设备进行压实。Most saturated soils that can be classified through silty and/or clay sands and

20、gravels can be considerably improved by this method.The amount of compaction tends to decrease with an increase in silt or clay content.对许多按粉质和（或）黏质砂土以及砾石进行分类的饱和土体来说，采用强夯可取得相当好的加固效果。随着粉粒或黏粒含量的增加，夯实的效果会逐渐降低。Saturated clays tend toward almost no improvement because the impact results in an instantaneo

21、usly high pore pressure,an immediate loss of shear strength,and remolding.Partially saturated clays may be improved,at least in the region above the GWT.强夯对饱和黏土几乎起不到任何加固作用，因为夯击可导致土体中产生较高的瞬时孔隙水压力，造成抗剪强度的瞬时丧失并发生重塑。部分饱和的黏土（至少在地下水位以上区域的土体)可采用强夯进行加固。In practice several trial grid sections are used to det

22、ermine the optimum drop spacing,drop weight(and/or height of fall),and number of drops.在实际工程中，可对若干工段进行试夯，以确定最佳的夯点距离、锤重（和/或落距）以及夯击遍数。Ordinarily,dynamic compaction/consolidation is only economical when1.Site plan involves an area of some 5000 to 10 000 m2.2.Depth of soil is too great to use excavation

23、 and replacement.3.Impact vibrations that are on the order of 2 to 12 Hz will not cause damage to nearby developments.一般情况下，强夯/动力固结只有在下述情况下才可以体现出其经济性：场地的平面面积约为500010000m2。土层的厚度过大，不能采用开挖和置换。冲击振动的频率约为212Hz，不会对附近的建设工程产生损害。Preloading This step is taken primarily to reduce future settlement but may also

24、be used to increase shear strength(抗剪强度).It is usually used in combination with(与.结合)drainage.此种方法主要用于减少将来的沉降，但也可用于提高土体的抗剪强度，一般与排水法结合使用。A relatively inexpensive,effective method to improve poor foundation soils in advance of(在.之前)construction of permanent facilities is preloading.在永久性设施施工以前，“预压法”是加固

25、软弱地基的一种相对比较经济和有效的方法。The preload may consist of soil,sand,or gravel;and in the case of oil or water tanks,gradual filling of the tanks may be used for the preload.预压荷载可以是土、砂或砾石，而如果是处理油罐或水箱地预压荷载可以是土、砂或砾石，而如果是处理油罐或水箱地基的情况，向罐内逐渐冲入的水即可作为预压荷载。基的情况，向罐内逐渐冲入的水即可作为预压荷载。Sometimes the preload may be accomplishe

26、d by lowering the groundwater table.有时还可通过降低地下水位来施加预压荷载。有时还可通过降低地下水位来施加预压荷载。It may also be accomplished by ponding,that is,building a watertight containment that is filled with water but requires protection against vandalism and unauthorized recreation(such as swimming).也可采用也可采用“人工池塘人工池塘”来施加预压荷载，即建造

27、一个充来施加预压荷载，即建造一个充水的不透水的容器水的不透水的容器但是需要采取保护措施以防范故意破坏及未但是需要采取保护措施以防范故意破坏及未经批准的娱乐活动（比如游泳）经批准的娱乐活动（比如游泳）。How or what to use to accomplish preloading will be determined by relative economics.如何进行预压或采用什么来实现预压将取决于相对的经济性。Aldrich(1965)see also Johnson(1970)conducted a survey among several organizations to pro

28、duce a report on preload practices that were current at that time.Aldrich（1965）亦可参见Johnson（1970）曾在若干单位进行了调查并提交了一份关于当时预压实践的发展水平报告。Precompression(or preloading)accomplishes two major goals:预压主要用于实现两个目的：1.Temporary surcharge loads are used to eliminate settlements that would otherwise occur after the s

29、tructure is completed.1)采用临时超载来消除建筑物建成后可能会发生的沉降。2.Preloading improves the shear strength of the subsoil by increasing the density,reducing the void ratio,and decreasing the natural water content wN.2)通过预压可增大土体的密实度、减少孔隙比降低其天然含水率wN，从而使地基土体的抗剪强度得到提高。Preloading is most effective on normal to lightly ove

30、rconsolidated silts,clays,and organic deposits.预压法对正常固结至弱超固结状态的粉土、黏土以及有机土层最为有效。If the deposits are thick and do not have alternating sand seams,the preloading may necessitate using sand drains to reduce the time necessary to effect consolidation.如果土层较厚且无砂夹层互层，预压法可能必需采用排水水砂井来缩短固结历时。Preloading does no

31、t seem to be much used at present since a number of other procedures can be used to improve the soil that are comparable in cost,allow more rapid access to the site,and do not require disposal of the excess preload material.预压法在目前似乎并不常用，因为还有许多其他的地基加固方法可供采用，这些方法在成本上与预压法相当，而工期却比预压法要短，且无需处置用于预压的堆载材料。In

32、 extremely soft cohesive and peaty deposits such as glacial lakes,river deltas,and peat bogs a procedure called displacement preloading may be used where haulers back to the site edge and dump the quality fill.对于特别软弱的黏性土和泥炭土层（例如冰川湖相和河流三角洲相的沉积土以及泥炭沼泽），可采用一种被成为“置换预压”的方法，运输设备以倒车的方式向场地边缘倾倒性质较好的填料。The fi

33、ll load induces a shear failure in the in situ soil,which causes it to displace laterally away from the fill.The lateral displacement usually produces viscous(sticky)waves in the soil called mud waves.填料荷载会导致现场的土体产生剪切破坏，并使得其侧向挤出。侧向挤出一般会在地基土体中形成被称为“泥浆波”的黏滞波纹。30 When there is enough fill accumulated i

34、t is compacted and the process continued until the desired area is stabilized.This procedure is of use for shoreline construction and has been used to produce causeways across lakes for railroad tracks and roadways.当堆积了足够的填料后，将其压实，继续重复上述过程当堆积了足够的填料后，将其压实，继续重复上述过程直至预期的区域得到加固。这种方法适用于沿岸工程并已直至预期的区域得到加固。

35、这种方法适用于沿岸工程并已被用于建造跨湖铁路和道路的路基。被用于建造跨湖铁路和道路的路基。in case/in case of/in the case of的用法及区别in case万一。是连词，引导条件状语从句。也就是说in case后面是一个完整的句子.Take a hat with you in case the sun is very hot.倘若太阳很利害，你就把帽子戴上。In case(=If)I forget,please remind me.万一我忘记，请提醒我。in case of 如果,万一,后接名词、代词或动名词。如:Take a spare tyre along in

36、case of need.带只备用轮胎去,以备不时之需。Turn off the TV set in case of thunderstorm.在雷雨时,关上电视机。In case of fire,dial 119 at once.如果发生火灾,立即拨打119。in the case of则是就来说。如:In the case of his health,it is fortunate for him to have recovered from his illness like this.就他的健康状况来说,能恢复到这样算是幸运的了。Failure is no shame in the ca

37、se of a scientist.就科学家来说,失败并非羞耻事。in any case 无论如何In any case,Ill come over to the office tomorrow.无论如何,我明天会来办公室的。in no case决不,置于句首时,须用倒装语序。如:In no case shall we allow smoking in the classroom.教室里决对不允许吸烟。tooto 句型的用法 该结构的基本形式为“too+形容词或副词+to+动词原形”，其意为“太以至于不能”：He is too tired to go any further.他太累了，不能再往前走了。He is too young to know right from wrong.他太小，还分不清是非。有时不定式前可以带有一个由介词for引出的逻辑主语：The box is too heavy for me to carry.这个箱子太重，我提不起。