外文翻譯--公路和機(jī)場(chǎng)路面設(shè)計(jì)

1、中文2942字本科生畢業(yè)設(shè)計(jì)（論文）外文資料翻譯翻譯資料名稱(chēng)（外文）： Highway and Airport Pavement Design 翻譯資料名稱(chēng)（中文）： 公路和機(jī)場(chǎng)路面設(shè)計(jì) 學(xué) 院： 建筑工程學(xué)院 系 土木工程 專(zhuān) 業(yè)： 土 木 工 程 （道橋） 班 級(jí)： 學(xué) 號(hào)： 姓 名： 指導(dǎo)教師： 完成日期： 2021 年 02 月 20 日14Highway and Airport Pavement Design（Excerpt）T. F. Fwa National University of Singapore1. Introduction Pavements are designed

2、 and constructed to provide durable all-weather traveling surfaces for safe and speedy movement of people and goods with an acceptable level of comfort to users. These functional requirements of pavements are achieved through careful considerations in the following aspects during the design and cons

3、truction phases: (a) selection of pavement type, (b) selection of materials to be used for various pavement layers and treatment of subgrade soils, (c) structural thickness design for pavement layers, (d) subsurface drainage design for the pavement system, (e) surface drainage and geometric design,

4、and (f ) ridability of pavement surface.The two major considerations in the structural design of highway and airport pavements are material design and thickness design. Material design deals with the selection of suitable materials for various pavement layers and mix design of bituminous materials (

5、for flexible pavement) or portland cement concrete (for rigid and interlocking block pavements). These topics are discussed in other chapters of this handbook. This chapter presents the concepts and methods of pavement thickness design. As the name implies, thickness design refers to the procedure o

6、f determining the required thickness for each pavement layer to provide a structurally sound pavement structure with satisfactory performance for the design traffic over the selected design life. Drainage design examines the entire pavement structure with respect to its drainage requirements and inc

7、orporates facilities to satisfy those requirements.2Pavement Types and Materials2.1 Flexible versus Rigid PavementTraditionally, pavements are classified into two categories, namely flexible and rigid pavements. The basis for classification is the way by which traffic loads are transmitted to the su

8、bgrade soil through the pavement structure. As shown in Fig. 2.1, a flexible pavement provides sufficient thickness for load distribution through a multilayer structure so that the stresses and strains in the subgrade soil layers are within the required limits. It is expected that the strength of su

9、bgrade soil would have a direct bearing on the total thickness of the flexible pavement. The layered pavement structure is designed to take advantage of the decreasing magnitude of stresses with depth. A rigid pavement, by virtue of its rigidity, is able to effect a slab action to spread the wheel l

10、oad over the entire slab area, as illustrated in Fig. 2.1. The structural capacity of the rigid pavement is largely provided by the slab itself. For the common range of subgrade soil strength, the required rigidity for a portland cement concrete slab (the most common form of rigid pavement construct

11、ion) can be achieved without much variation in slab thickness. The effect of subgrade soil properties on the thickness of rigid pavement is therefore much less important than in the case of flexible pavement. FIGURE 2.1 Flexible and rigid pavements.2.2 Layered Structure of Flexible Pavement2.2.1 Sur

12、face CourseIn a typical conventional flexible pavement, known as asphalt pavement, the surface course usually consists of two bituminous layers a wearing course and a binder course. To provide a durable, watertight, smooth-riding, and skid-resistant traveled surface, the wearing course is often cons

13、tructed of dense-graded hot mix asphalt with polish-resistant aggregate. The binder course generally has larger aggregates and less asphalt. The composition of the bituminous mixtures and the nominal top size aggregates for the two courses are determined by the intended use, desired surface texture

14、(for the case of wearing course), and layer thickness. A light application of tack coat of water-diluted asphalt emulsion may be used to enhance bonding between the two courses. Table 2.1 shows selected mix compositions listed in ASTM Standard Specification D3515 1992. Open-graded wearing courses, s

15、ome with air void exceeding 20%, have also been used to improve skid resistance and reduce splash during heavy rainfall by acting as a surface drainage layer. 2.2.2 Base CourseBase and subbase layers of the flexible pavement make up a large proportion of the total pavement thickness needed to distri

16、bute the stresses imposed by traffic loading. Usually base course also serves as a drainage layer and provides protection against frost action. Crushed stone is the traditional material used for base construction to form what is commonly known as the macadam base course. In this construction, chokin

17、g materials consisting of natural sand or the fine product resulting from crushing coarse aggregates are added to produce a denser structure with higher shearing resistance. Such base courses are called by different names, depending on the construction method adopted. Dry-bound macadam is compacted

18、by means of rolling and vibration that work the choking materials into the voids of larger stones. For water-bound macadam, after spreading of the choking materials, water is applied before the entire mass is rolled. Alternatively, a wet-mix macadam may be used by premixing crushed stone or slag wit

19、h a controlled amount of water. The material is spread by a paving machine and compacted by a vibrating roller. Granular base materials may be treated with either asphalt or cement to enhance load distribution capability. Bituminous binder can be introduced by spraying heated asphalt cement on conso

20、lidated and rolled crushed stone layer to form a penetration macadam road base. Alternatively, bituminous road bases can be designed and laid as in the case for bituminous surface courses. Cement-bound granular base material is plant mixed with an optimal moisture content for compaction. It is laid

21、by paver and requires time for curing. Lean concrete base has also been used successfully under flexible pavements. TABLE 2.1 Example Composition of Dense Bituminous Paving Mixtures2.2.3 Subbase CourseThe subbase material is of lower quality than the base material in terms of strength, plasticity, a

22、nd gradation, but it is superior to the subgrade material in these properties. It may be compacted granular material or stabilized soil, thus allowing building up of sufficient thickness for the pavement structure at relatively low cost. On a weak subgrade, it also serves as a useful working platfor

23、m for constructing the base course. subbase course may be omitted if the subgrade soil satisfies the requirements specified for subbase material.2.2.4 Prepared SubgradeMost natural soils forming the roadbed for pavement construction require some form of preparation or treatment. The top layer of a s

24、pecified depth is usually compacted to achieve a desired density. The depth of compaction and the compacted density required depend on the type of soil and magnitudes of wheel loads and tire pressures. For highway construction, compaction to 100% modified AASHTO density covering a thickness of 12 in

25、. (300 mm) below the formation level is commonly done. Compaction depth of up to 24 in. (600 mm) may be required for heavily trafficked pavements. For example, in the case of cohesive subgrade, the Asphalt Institute 1991 requires a minimum of 95% of AASHTO T180 (Method D) density for the top 12 in.

26、(300 mm) and a minimum of 90% for all fill areas below the top 12 in. (300 mm). For cohesionless subgrade, the corresponding compaction requirements are 100 and 95%, respectively.Due to the higher wheel loads and tire pressures of aircraft, many stringent compaction requirements are found in airport

27、 pavement construction.In some instances it may be economical to treat or stabilize poor subgrade materials and reduce the total required pavement thickness. Portland cement, lime, and bitumen have all been used successfully for this purpose. The choice of the method of stabilization depends on the

28、soil properties, improvement expected, and cost of construction.2.3 Rigid PavementRigid pavements constructed of portland cement concrete are mostly found in heavy-traffic highways and airport pavements. To allow for expansion, contraction, warping, or breaks in construction of the concrete slabs, j

29、oints are provided in concrete pavements. The joint spacing, which determines the length of individual slab panels, depends on the use of steel reinforcements in the slab. The jointed plain concrete pavemen (JPCP), requiring no steel reinforcements and thus the least expensive to construct, is a pop

30、ular form of construction. Depending on the thickness of the slab, typical joint spacings for plain concrete pavements are between 10 and 20 ft (3 and 6 m). For slabs with joint spacing greater than 6 m, steel reinforcements have to be provided for crack control, giving rise to the use of jointed re

31、inforced concrete pavements (JRCP) and continuously reinforced concrete pavements (CRCP). Continuously reinforced concrete pavements usually contain higher than 0.6% steel reinforcement to eliminate the need to provide joints other than construction and expansion joints. The base course for rigid pa

32、vement, sometimes called subbase, is often provided to prevent pumping (ejection of foundation material through cracks or joints resulting from vertical movement of slabs under traffic). The base course material must provide good drainage and be resistant to the erosive action of water. When dowel b

33、ars are not provided in short jointed pavements, it is common practice to construct cement-treated base to assist in load transfer across the joints.3Considerations for Highway and Airport PavementsThe two pavement types, flexible and rigid pavement, have been used for road and airport pavement cons

34、truction. The choice of pavement type depends on the intended functional use of the pavement (such as operating speed and safety requirements), types of traffic loading, cost of construction, and maintenance consideration.The main differences in design considerations for highway and airport pavement

35、s arise from the characteristics of traffic using them. Over the typical design life span of 10 to 20 years for flexible pavements, or 20 to 40 years for rigid pavements, a highway pavement will be receiving highly channelized wheel load applications in the millions. Consideration of the effects of

36、load repetitions such as cumulative permanent deformation, crack propagation, and fatigue failure becomes important. The total number of load applications in the entire design life of a highway pavement must therefore be known for pavement structural design. In contrast, the frequency of aircraft lo

37、ading on airport pavement is much less. There are also the so-called wander effect of aircraft landing and taking off and the large variation in the wheel assembly configurations and layout of different aircraft. These make wheel loading on airport pavements less channelized than on highway pavement

38、s. Identification of the most critical aircraft is therefore necessary for structural design of airport pavements. Another important difference is in the magnitude of wheel loads. Airport pavements receive loads far exceeding those applied on the highway. An airport pavement may have to be designed

39、to withstand equivalent single wheel loads of the order of 50 t (approximately 50 tons), whereas the maximum single wheel load allowed on the road pavement by most highway authorities is about 10 t (approximately 10 tons). Furthermore, the wheel tire pressure of an aircraft of about 1200 kPa (175 ps

40、i) is nearly twice the value of a normal truck tire. These differences greatly influence the material requirements for the pavements.公路和機(jī)場(chǎng)路面設(shè)計(jì)（節(jié)選）T. F. Fwa新加坡國(guó)立大學(xué)1.緒論路面的設(shè)計(jì)和建造是為了能夠給行人和貨物在其上面進(jìn)行全天候持久的安全迅速活動(dòng)提供一個(gè)舒適合意的水平環(huán)境。路面的這些功能要求可以通過(guò)在設(shè)計(jì)和施工過(guò)程中仔細(xì)考慮如下幾個(gè)方面來(lái)實(shí)現(xiàn)：（a）合理選擇路面類(lèi)型；（b）合理選擇各路面層材料和路基土處理；（c）合理進(jìn)行各路面層厚度劃分

41、；（d）地下排水系統(tǒng)設(shè)計(jì)；（e）路面排水系統(tǒng)和幾何尺寸設(shè)計(jì)；（f）路面的抵抗能力。公路和機(jī)場(chǎng)路面在結(jié)構(gòu)設(shè)計(jì)上的兩個(gè)主要考慮因素是材料設(shè)計(jì)和厚度設(shè)計(jì)。材料設(shè)計(jì)要合理選擇各路面層材料，滿(mǎn)足瀝青混合料（柔性路面）或者水泥混凝土（剛性路面）配合比設(shè)計(jì)要求。這些問(wèn)題將在本手冊(cè)的其他章節(jié)中進(jìn)行討論。本章介紹路面厚度設(shè)計(jì)的概念和方法。顧名思義，厚度設(shè)計(jì)是指確定每個(gè)路面層的厚度，形成一個(gè)穩(wěn)定的路面結(jié)構(gòu)，使得在規(guī)定的設(shè)計(jì)年限內(nèi)滿(mǎn)足設(shè)計(jì)交通量的要求。排水系統(tǒng)設(shè)計(jì)可檢驗(yàn)整個(gè)路面結(jié)構(gòu)在它的排水要求和一體化設(shè)施方面是否滿(mǎn)足相關(guān)要求。2. 路面類(lèi)型和材料2.1柔性路面和剛性路面?zhèn)鹘y(tǒng)上，根據(jù)通過(guò)路面結(jié)構(gòu)傳遞到路基土上的交通

42、荷載，路面分為兩類(lèi)，即柔性路面和剛性路面。如圖2.1所示，柔性路面具有足夠的厚度來(lái)承受多層結(jié)構(gòu)傳遞的分布荷載，使得路基土層的應(yīng)力應(yīng)變值控制在容許范圍內(nèi)。柔性路面地基土的強(qiáng)度將直接關(guān)系到總厚度。路面結(jié)構(gòu)層的設(shè)計(jì)充分利用到了應(yīng)力隨著土層的加深而減少這一原理。剛性路面依靠其剛度，能夠有效傳遞作用在整塊混凝土板塊上的車(chē)輛荷載，如圖2.1所示。剛性路面的結(jié)構(gòu)承載力大部分都是由混凝土板塊自身提供。在地基土強(qiáng)度的一般變化范圍內(nèi)，硅酸鹽水泥混凝土面板（最常見(jiàn)的剛性路面結(jié)構(gòu)）的剛度要求無(wú)需板塊厚度發(fā)生多大變化就能滿(mǎn)足。因此，路基土性能對(duì)剛性路面厚度的影響要比柔性路面小得多。圖2.1 柔性和剛性路面2.2 柔性路

43、面結(jié)構(gòu)層次2.2.1 面層瀝青路面是一種典型的傳統(tǒng)柔性路面，它的面層通常由兩個(gè)瀝青層組成，即磨耗層和聯(lián)結(jié)層。為了保證路面的耐久性、不透水、平穩(wěn)行車(chē)和防滑，磨耗層一般由熱拌瀝青混凝土和耐磨碎石組成，而聯(lián)結(jié)層則一般由大量的碎石和少量的瀝青組成。這兩層的瀝青混合料的組成以及骨料的最大公稱(chēng)直徑是由使用目的、所希望的表面結(jié)構(gòu)（針對(duì)磨耗層而言）、層厚來(lái)決定的。由水稀釋乳化瀝青組成的粘結(jié)層的一個(gè)簡(jiǎn)易運(yùn)用就是增強(qiáng)磨耗層和聯(lián)結(jié)層之間的粘結(jié)性。表2.1顯示了列在ASTM標(biāo)準(zhǔn)規(guī)格D35151992 上的經(jīng)選定的混合成分。有些空隙率超過(guò)20%的開(kāi)級(jí)配磨耗層也可作為強(qiáng)降雨天氣時(shí)的地面排水層，用于提高抗滑性和防止濺水。2

44、.2.2 基層柔性路面的基層和底基層占總路面厚度的大部分，它們用來(lái)分配交通荷載所產(chǎn)生的應(yīng)力。通?；鶎右部勺鳛榕潘畬?，并提供保護(hù)免受霜凍作用。碎石是基層施工的常用材料，構(gòu)成俗稱(chēng)的碎石基層。在本階段施工過(guò)程中，填充材料選用天然砂或者良好級(jí)配的壓碎碎石集料，形成具有更高抗剪承載力的密實(shí)結(jié)構(gòu)。根據(jù)施工方法的不同，這樣的基層有不同名稱(chēng)。表2.1 濃瀝青攤鋪混合料組成示例干結(jié)碎石通過(guò)軋制和振動(dòng)，使填充料填塞到大塊石頭間的空隙，達(dá)到壓實(shí)的目的。而對(duì)于水結(jié)碎石，在填充材料填塞空隙后，水在整塊被軋制前就得到應(yīng)用。另外，通過(guò)用適量的水預(yù)拌碎石或礦渣，濕混碎石也可被使用。這些材料先用攤鋪機(jī)攤鋪，然后再用振動(dòng)壓路機(jī)壓

45、實(shí)。顆?；鶎硬牧峡蛇x用瀝青或者水泥以提高荷載分配能力。為建造滲透碎石路面基層，在固結(jié)并壓實(shí)的碎石層上面噴灑熱拌瀝青混凝土?xí)r可采用瀝青結(jié)合料。瀝青路面基層的設(shè)計(jì)和攤鋪可以作為瀝青面層的示例。水泥穩(wěn)定基層粒料在達(dá)到壓實(shí)時(shí)的最佳含水量后采用廠拌法，通過(guò)攤鋪機(jī)攤鋪，養(yǎng)護(hù)足夠的時(shí)間。貧混凝土基層也被成功運(yùn)用到柔性路面。2.2.3 底基層跟基層材料相比，底基層材料的強(qiáng)度、塑性和級(jí)配要求都要更低，但是在這些性能上，底基層更具優(yōu)勢(shì)?？赡芤?yàn)椴捎昧藟簩?shí)粒料或穩(wěn)定土，路面結(jié)構(gòu)造價(jià)相對(duì)較低，但厚度卻足以滿(mǎn)足要求。對(duì)于柔弱底基層，它也可以作為構(gòu)建基層的有用的施工平臺(tái)。如果路基土滿(mǎn)足底基層材料的特定要求，也可以不構(gòu)建底

46、基層。2.2.4 素土夯實(shí)層用于路面建筑的絕大部分天然土路床要求進(jìn)行素土夯實(shí)或者特殊處理。某一指定深度的頂層通常需要壓實(shí)來(lái)獲得理想的壓實(shí)密度。壓實(shí)深度和壓實(shí)密度的要求要根據(jù)土壤類(lèi)型、車(chē)輪荷載大小以及輪胎壓力而定。在公路建筑上，壓實(shí)至100%修改過(guò)的 AASHTO（美國(guó)國(guó)家公路與運(yùn)輸協(xié)會(huì)標(biāo)準(zhǔn)）密度時(shí)，覆蓋厚度為12英寸 (300毫米)，通常的做法都是低于這個(gè)正常水平的。對(duì)于重交通路面，壓實(shí)深度可能要求高達(dá)24英寸（600毫米）。例如，對(duì)于粘性路基，瀝青研究所（1991）要求達(dá)到最低的95%AASHTO標(biāo)準(zhǔn) T180次 (D法)密度時(shí)，厚度為頂級(jí)12英寸（300毫米），在所有填方中最少90%要低于

47、頂級(jí)12英寸（300毫米）。對(duì)于無(wú)粘性路基，相應(yīng)的壓實(shí)要求是100%和95%。由于飛機(jī)的輪載和輪壓更大，因此在機(jī)場(chǎng)路面施工時(shí)，對(duì)壓實(shí)要求更為嚴(yán)格。在某些情況下，處理或者加固軟弱不良路基材料是一種經(jīng)濟(jì)的做法，并且可以減少所需的總路面厚度。硅酸鹽水泥、石灰、瀝青等的成功運(yùn)用就是為了達(dá)到這樣的效果。選擇怎樣的加固方法要根據(jù)土壤性質(zhì)、預(yù)期改善效果和建設(shè)成本而定。2.3 剛性路面在交通繁忙的公路和機(jī)場(chǎng)路面，硅酸鹽水泥混凝土剛性路面結(jié)構(gòu)幾乎隨處可見(jiàn)?？紤]到混凝土板的膨脹、收縮、翹曲或者開(kāi)裂，混凝土路面設(shè)有接縫。接縫間距取決于混凝土板中鋼筋的選用，它能決定單獨(dú)每板塊的長(zhǎng)度。接縫式素混凝土路面結(jié)構(gòu)（JPCP）

48、是一種很流行的建筑形式，它不需要鋼筋，因而造價(jià)最低。根據(jù)混凝土板厚度的大小，普通混凝土路面的標(biāo)準(zhǔn)接縫間距是1020英尺（36米）。當(dāng)混凝土板塊接縫間距大于6米時(shí)，需要增設(shè)鋼筋防止開(kāi)裂，從而進(jìn)入到使用接縫式鋼筋混凝土路面（JRCP）和連續(xù)鋼筋混凝土路面（CRCP）階段。連續(xù)鋼筋混凝土路面通常多含0.6%的鋼筋，用來(lái)減少除結(jié)構(gòu)和伸縮縫以外的接縫數(shù)量。剛性路面基層，有時(shí)又叫做底基層，通常用于防止出現(xiàn)唧泥（在交通作用下，混凝土板垂直運(yùn)動(dòng)，基礎(chǔ)材料通過(guò)裂縫或者接縫噴出的現(xiàn)象）?；鶎硬牧媳仨毦哂辛己玫呐潘阅懿⑶夷軌虻挚顾母g作用。當(dāng)短縫路面沒(méi)有傳力桿時(shí)，通常的做法是構(gòu)建水泥穩(wěn)定基層來(lái)協(xié)助傳遞橫穿接縫的

49、荷載。3. 公路和機(jī)場(chǎng)路面注意事項(xiàng)柔性路面和剛性路面這兩種路面類(lèi)型已經(jīng)廣泛運(yùn)用到了公路和機(jī)場(chǎng)路面建筑。選擇哪種路面類(lèi)型要根據(jù)路面的預(yù)期使用功能（例如運(yùn)行速度和安全要求）、交通荷載類(lèi)型、工程造價(jià)和維修代價(jià)而定。公路和機(jī)場(chǎng)路面設(shè)計(jì)考慮因素方面主要的不同在于使用它們的交通特點(diǎn)各異。柔性路面的標(biāo)準(zhǔn)設(shè)計(jì)年限是10-20年，剛性路面是20-40年，在它們各自的設(shè)計(jì)年限內(nèi)，公路路面將受到數(shù)于百萬(wàn)計(jì)的高渠化輪載作用?？紤]到重復(fù)荷載的影響例如累積永久變形、裂紋擴(kuò)展和疲勞破壞變得重要，路面結(jié)構(gòu)設(shè)計(jì)必須考慮到整個(gè)設(shè)計(jì)年限范圍內(nèi)的荷載作用總效應(yīng)。相比之下，機(jī)場(chǎng)路面的負(fù)荷頻率要小得多。所謂的飛機(jī)著陸、起飛漂移，大差異的

50、機(jī)輪裝配配置，不同飛機(jī)的布局設(shè)計(jì)，這些因素使得作用在機(jī)場(chǎng)路面的輪載渠化程度比公路路面低。因此在機(jī)場(chǎng)路面的結(jié)構(gòu)設(shè)計(jì)中，以最關(guān)鍵的飛機(jī)為標(biāo)準(zhǔn)是很有必要的。另外一個(gè)重要的不同就在于輪載的大小。機(jī)場(chǎng)路面受到的荷載遠(yuǎn)大于作用在公路上的。機(jī)場(chǎng)路面要設(shè)計(jì)能夠承受50噸（或接近50噸）的等效單輪荷載，然而大部分公路部門(mén)所允許的最大公路路面單輪荷載只有10噸（或接近10噸）。此外，一架飛機(jī)的輪胎壓力大約是1200KP（175磅），接近于兩倍的標(biāo)準(zhǔn)卡車(chē)輪胎壓力。這些不同因素對(duì)路面材料的要求影響都很大。 教師見(jiàn)習(xí)報(bào)告總結(jié)期待已久的見(jiàn)習(xí)已經(jīng)結(jié)束了，在龍巖三中高中部見(jiàn)習(xí)聽(tīng)課，雖然只是短短的兩個(gè)星期，但感觸還是蠻深的，以

51、前作為一名學(xué)生坐在課室聽(tīng)課，和現(xiàn)在作為一名準(zhǔn)教師坐在課室聽(tīng)課是完全不同的感受，感覺(jué)自己學(xué)到了一些在平時(shí)課堂上學(xué)不到的東西。在這里，我獲得的不僅是經(jīng)驗(yàn)上的收獲，更多是教學(xué)管理，課堂教學(xué)等的理念，以及他們帶給我的種種思考。教育見(jiàn)習(xí)實(shí)踐過(guò)程：聽(tīng)課。教育見(jiàn)習(xí)的主要目的是讓學(xué)生在指導(dǎo)教師的引導(dǎo)下，觀摩教師上課方法、技巧等。聽(tīng)課是教育見(jiàn)習(xí)的主要內(nèi)容。我院規(guī)定在一周的見(jiàn)習(xí)中需完成至少6課的見(jiàn)習(xí)任務(wù)。我在教師的安排指導(dǎo)下，分別對(duì)高一、高二物理專(zhuān)業(yè)課型為主，其他課型齊頭的方式，積極主動(dòng)的完成了聽(tīng)課任務(wù)，收到良好的效果。我聽(tīng)的第一節(jié)課是高二（8）班，這是一個(gè)平衡班，水平不如實(shí)驗(yàn)班高。在上課前?？迫卫蠋熞呀?jīng)跟我說(shuō)了這個(gè)班的紀(jì)律是比較差的，而且成績(jī)也不是很好。在我聽(tīng)課期間，確實(shí)有幾個(gè)學(xué)生在課堂上說(shuō)話(huà)，但是我發(fā)現(xiàn)了一個(gè)有趣的現(xiàn)象，這個(gè)現(xiàn)象我在往后的幾個(gè)班都發(fā)現(xiàn)了，就是絕大部分的學(xué)生的學(xué)習(xí)熱情都好高漲，積極舉手發(fā)言，積極參與課堂活動(dòng)。我跟老師們提起這個(gè)現(xiàn)象的時(shí)候，科任老師就跟我說(shuō)，一個(gè)班里不可能所有的學(xué)生都能全神貫注地聽(tīng)完一節(jié)課，所以作為一名教師，應(yīng)該想辦法吸引學(xué)生的注意力，調(diào)動(dòng)的積極性，比如可以以