土木工程專業(yè)英語unit4(3)課件

1、 Unit 4 Soil Improvement 地基處理Learning Guidance Master:The reasons and purposes of soil improvement; the methods of soil improvement掌握：地基處理的原因和目的；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:壓實法(Compaction) 預壓法(Preloading) 排水法(Drainage) 灌漿法(

2、Grouting) 振沖法(Vibroflotation)New Words and Phrases1. replacement n. 置換2. compaction n. 壓實3. preload n. 預壓4. drainage n. 排水5. backfill v./n. 回填6. granular adj. 顆粒的；粒狀的7. watertight adj. 水密的；不漏水的8. precompression n. 預壓縮9. permeability n. 滲透性10. cement n. 水泥；接合劑11. centrifugal adj. 離心的 n. 離心機v.鞏固/加強syn

3、onym: consolidate/solidify/enhance/intensify/strengthenPhrases12. soil improvement 地基處理13. shear strength 抗剪強度14. impact vibration 沖擊振動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；排水砂樁19. consolidating stratum 固結土層20. mandrel-driven pipes 套管法21. driven pipes 打入管

4、法22. rotary drill 回轉鉆進法23. continuous-flight hollow auger 空心螺旋鉆法24. wick drain 排水芯板25. textile filter blanket 織物濾水墊層26. horizontal trench drain 水平排水溝槽27. jet grouting 旋噴灌漿法28. vibroflotation 振沖法29. soil excavation 土體開挖30. in advance of 超過；在的前面31. in combination with 與相結合；與聯(lián)合Introduction樓倒倒樓倒倒樓歪歪Part

5、 I Soil ImprovementIntroduction： Geotechnical considerations will primarily be on strength and deformation and those soilwater phenomena that affect strength and deformation. 土體的強度和變形以及土中水對強度和變形的影響是土木工程的基本問題。With the current trend to using sites with marginal soil parameters for major projects, meth

6、ods to improve the strength and deformation characteristics through soil improvement will be briefly considered in this chapter. 目前的趨勢是將大型工程建在土體性質較差的場地之上（因為好的場地已所剩無幾），因此本章將會簡要介紹通過地基加固來提高土體強度和變形特性的方法。 The centuries-old problem of land scarcity in the vicinity(臨近、附近) of existing urban areas often nece

7、ssitates the use of sites with soils of marginal quality.數(shù)個世紀以來現(xiàn)有城區(qū)附近土地缺乏的老問題經常使得必須利用具有不良土層的場地。 In many cases these sites can be utilized for the proposed project by using some kind of soil improvement.在許多情況下，這些場地需要地基加固后才能用于擬建工程。 marginal lands：貧瘠的土地 marginal seat：邊緣席位marginal improvement ：略有增長a mar

8、ginal 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. 地基處理的目的是通過使用置換、壓實、預壓和排水等各種方法對地基進行加固，以改良土的特性。Here，we will focus on several of the more widely used

9、 methods of improving soils for bearing capacity.在此，我們著重介紹廣泛用于提高地基承載力的幾種地基加固方法。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 site one may use a mix of several methods to

10、 achieve the desired result.已有大量的地基加固方法被使用過且（或）在相關文獻中報道過，其中的許多方法也已經申請了專利。而對于一個具體的場地，可采用數(shù)種方法相結合以達到預期的效果。n.national patent 國家專利 patent law 專利法，專利權法 patent application 專利申請書 patent protection 專利保護 product patent 產品專利權 patent holder 專利持有方adj.顯然的（obvious/evident/apparent）v.授予專利/取得.專利CompactionCompaction(

11、壓實法) is usually an economical method of improving the bearing capacity(地基承載力) of site soils.壓實法一般是一種提高場地地基承載力成本較低的方法。It may be accomplished by excavating(挖掘) to some depth, then carefully backfilling in controlled lift thicknesses, (each of which) is compacted with the appropriate compaction equipme

12、nt. 它的做法是先下挖至一定深度，然后按控制的填筑層厚仔細回填，并對每一填筑層采用適當?shù)膲簩嵲O備壓實。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. 對于無黏性土和黏性土，這種方法是使得土粒排列密實的最為經濟的方法，它一般需要采用某種碾壓裝置。Dynamic compaction(強夯) is a specia

13、l type of compaction consisting of(由.組成) dropping heavy weights on the soil. “強夯”是將重錘由高空落向地基土體的一種特殊壓實方法。14 4.soil improvement 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. Menard in France ca. 1970 . 盡管使

14、重物落向地面的方法或許已被使用了幾個世紀之久，但是約在1970年法國工程師L.Menard才將其從專業(yè)角度重新引入并取得專利。Compaction can be achieved to a substantial depth depending on weight (or mass) of the tamper, height of fall, and the type of soil.相當大深度內的土體可得到夯實，強夯的加固深度與夯錘的重量（或質量）、落距以及土的類型有關。tamper: n. 夯具v.篡改(distort) 損害/削弱(harm/damage/injure) 賄賂(brib

15、e/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 adequately covered. 雖然

16、在強夯法中夯錘的質量可達150000kg（或150t），但在一般情況下其質量約為1020t，夯錘從最高可達40m（一般為1020m）的高度落下，夯點的布置形式可采用網格狀，使之充分覆蓋需要加固的場地。Craters ranging from 0.5 to 2 m in depth are produced at the points of impact.在夯點處可產生深為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 g

17、raded with a bulldozer(推土機) 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 based on before and after penetration tests (either SPT or CPT). 當需要夯實的區(qū)域被夯擊一遍后（夯點為網格上的每一個交點），采用推土機來平土方（如有必要還應運入新土以

18、整平場地表面），然后進行下一遍夯擊，如此重復直至達到預期的密實度。密實度一般可根據夯擊前后的觸探試驗（SPT或CPT）來確定。Penetration tests: 觸探試驗，它是一種常用的原位測試技術。由于其設備簡單、易于操作、使用效率高而應用較為廣泛。實驗方法包括動力觸探（DPT: Dynamic penetration test）、 標準貫入（SPT: Standard penetration test）和 靜力觸探（CPT: Cone penetration test）三類After the site improvement is completed, the area is broug

19、ht to grade and compacted with ordinary compaction equipment.在對整個場地采用強夯加固完畢后，應對場地進行整平并采用常規(guī)的壓實設備進行壓實。Most saturated soils that can be classified through silty and/or clay sands and gravels can be considerably improved by this method. The amount of compaction tends to decrease with an increase in silt

20、 or clay content. 對許多按粉質和（或）黏質砂土以及礫石進行分類的飽和土體來說，采用強夯可取得相當好的加固效果。隨著粉?；蝠ち：康脑黾?，夯實的效果會逐漸降低。Saturated clays tend toward almost no improvement because the impact results in an instantaneously high pore pressure, an immediate loss of shear strength, and remolding. Partially saturated clays may be improved

21、, at least in the region above the GWT.強夯對飽和黏土幾乎起不到任何加固作用，因為夯擊可導致土體中產生較高的瞬時孔隙水壓力，造成抗剪強度的瞬時喪失并發(fā)生重塑。部分飽和的黏土（至少在地下水位以上區(qū)域的土體)可采用強夯進行加固。In practice several trial grid sections are used to determine the optimum drop spacing, drop weight (and/or height of fall), and number of drops.在實際工程中，可對若干工段進行試夯，以確定最佳的

22、夯點距離、錘重（和/或落距）以及夯擊遍數(shù)。 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 and replacement.3. Impact vibrations that are on the order of 2 to 12 Hz will not cause damage to nearby d

23、evelopments. 一般情況下，強夯/動力固結只有在下述情況下才可以體現(xiàn)出其經濟性：場地的平面面積約為500010000m2。土層的厚度過大，不能采用開挖和置換。沖擊振動的頻率約為212Hz，不會對附近的建設工程產生損害。Preloading This step is taken primarily to reduce future settlement but may also be used to increase shear strength(抗剪強度).It is usually used in combination with(與.結合) drainage. 此種方法主要用于減

24、少將來的沉降，但也可用于提高土體的抗剪強度，一般與排水法結合使用。 A relatively inexpensive, effective method to improve poor foundation soils in advance of(在.之前) construction of permanent facilities is preloading. 在永久性設施施工以前，“預壓法”是加固軟弱地基的一種相對比較經濟和有效的方法。The preload may consist of soil, sand, or gravel; and in the case of oil or wat

25、er tanks, gradual filling of the tanks may be used for the preload.預壓荷載可以是土、砂或礫石，而如果是處理油罐或水箱地基的情況，向罐內逐漸沖入的水即可作為預壓荷載。 Sometimes the preload may be accomplished by lowering the groundwater table. 有時還可通過降低地下水位來施加預壓荷載。It may also be accomplished by ponding, that is, building a watertight containment tha

26、t is filled with water but requires protection against vandalism and unauthorized recreation (such as swimming).也可采用“人工池塘”來施加預壓荷載，即建造一個充水的不透水的容器但是需要采取保護措施以防范故意破壞及未經批準的娛樂活動（比如游泳）。How or what to use to accomplish preloading will be determined by relative economics. 如何進行預壓或采用什么來實現(xiàn)預壓將取決于相對的經濟性。Aldrich (

27、1965) see also Johnson (1970) conducted a survey among several organizations to produce a report on preload practices that were current at that time.Aldrich（1965）亦可參見Johnson（1970）曾在若干單位進行了調查并提交了一份關于當時預壓實踐的發(fā)展水平報告。Precompression (or preloading) accomplishes two major goals:預壓主要用于實現(xiàn)兩個目的：1. Temporary su

28、rcharge loads are used to eliminate settlements that would otherwise occur after the structure is completed.1) 采用臨時超載來消除建筑物建成后可能會發(fā)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) 通過預壓可增大土體

29、的密實度、減少孔隙比降低其天然含水率wN，從而使地基土體的抗剪強度得到提高。Preloading is most effective on normal to lightly overconsolidated silts, clays, and organic deposits. 預壓法對正常固結至弱超固結狀態(tài)的粉土、黏土以及有機土層最為有效。If the deposits are thick and do not have alternating sand seams, the preloading may necessitate using sand drains to reduce th

30、e time necessary to effect consolidation.如果土層較厚且無砂夾層互層，預壓法可能必需采用排水水砂井來縮短固結歷時。Preloading does not 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 exc

31、ess preload material.預壓法在目前似乎并不常用，因為還有許多其他的地基加固方法可供采用，這些方法在成本上與預壓法相當，而工期卻比預壓法要短，且無需處置用于預壓的堆載材料。In 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 qual

32、ity fill. 對于特別軟弱的黏性土和泥炭土層（例如冰川湖相和河流三角洲相的沉積土以及泥炭沼澤），可采用一種被成為“置換預壓”的方法，運輸設備以倒車的方式向場地邊緣傾倒性質較好的填料。The fill 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.填料荷載會導致現(xiàn)場的土體產生剪切破壞，并使得其側向擠出。側向擠出一般會在地基土體中形成被稱為“泥漿波”的黏滯波紋。30 When there is enough fill accumulated it 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