柔性路面外文翻譯

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3、 日 </p><p><b>　　柔性路面設(shè)計(jì)</b></p><p>　　一般來(lái)講，路面(和路基)可以分為兩種類型：剛性路面和柔性路面?！皠傂月访妗币辉~在美國(guó)通常指由普通水泥混凝土修筑的道路面層。人們認(rèn)為，混凝土路面可以像梁一樣具有較高的彎曲強(qiáng)度并能夠跨越基層或路基上一些微小的小平整的地帶，因此稱為“剛性”。同樣，支撐磚層或砌體層的混凝土基座也可以說(shuō)成是剛性的。

4、 </p><p>　　所有其他形式的路面在傳統(tǒng)上都被歸類于柔性路面。柔性路面的一個(gè)常用的定義是：柔性路面是與路基緊密接觸，并將荷載傳遞給路基的一種結(jié)構(gòu),它依靠集料之間的嵌擠力、顆粒的摩擦力和黏結(jié)力來(lái)保持其穩(wěn)定性。因此，傳統(tǒng)的柔性路面主要是指那些在許多粒料層的上面鋪上比較薄的高質(zhì)量的瀝青面層所構(gòu)成的路面。通常將有優(yōu)質(zhì)材料用于面層或面層附近。應(yīng)該指出，某些瀝青路面與傳統(tǒng)的剛性路面有很大的相似性，例如，鋪有較厚瀝青面

5、層的路面或由瀝青、水泥、石灰/粉煤灰所構(gòu)成的集料組成的基層的路面。然而，為便于說(shuō)明，這些路面被認(rèn)為是柔性的。在高速公路建設(shè)中，由于瀝青路面具有表面平整、行車舒適、耐磨抗滑、低噪聲、施工周期短、維修簡(jiǎn)便等特點(diǎn)，而被廣泛應(yīng)用。人們乘車在高速公路上行駛，平整度能直接反映高速公路通車后的整體效果，是體現(xiàn)路面使用品質(zhì)與行車舒適性的最直接的外觀指標(biāo)。</p><p>　　柔性路面的結(jié)構(gòu)由面層、基層、底基層(有時(shí)不采用)和路基

6、組成。其中面層和基層通常由兩層或更多層組成，每一層的材料成分不完全相同并采用分層鋪設(shè)的施工方法。對(duì)于許多承受重載的道路的路面，要選擇合適的底基層材料，鋪設(shè)于基層與路基之間。對(duì)于低成本、交通量不大的道路的瀝青路面，面層的厚度不應(yīng)低于1in；對(duì)于交通量繁忙的道路，采用瀝青混凝上面層，其厚度要達(dá)到6in 或者更厚一些。面層必須能夠 承受車輛行駛時(shí)所產(chǎn)生的磨蝕作用，并具有足夠的穩(wěn)定性來(lái)抵 抗車輛荷載作用下的推擠和碾壓。除此之人外，面層還應(yīng)該能有

7、效地阻止過(guò)量的表面積水滲入到其下的基層和路基中去。 </p><p>　　基層由一層(或多層) 穩(wěn)定性和密度很高的材料組成。它的主要作用是將車輛荷載作用于面層時(shí)所產(chǎn)生的應(yīng)力分布或“分散”傳遞，使得傳到路基中的應(yīng)力不會(huì)使其產(chǎn)生過(guò)大的變形和位移?；鶎舆€必須具有能夠抵抗由毛細(xì)水或冰凍作用產(chǎn)生的損害的性能。以往“基層不平面層調(diào)，下層不平上層找”的老方法，對(duì)平整度要求很高的高速公路來(lái)說(shuō)是根本行不通的。如規(guī)范允許基層頂面偏差

8、10mm，當(dāng)用瀝青混合料將10mm低洼處填平時(shí)，盡管表面是鋪平了，但該處多出的10mm松厚經(jīng)壓實(shí)后仍會(huì)出現(xiàn)低洼現(xiàn)象，其深度為10-（10／1.2）＝1.7mm(1.2為瀝青混合料平均壓實(shí)系數(shù))。如誤差大于10mm則不平整度將更大，由此可見(jiàn)基層頂面的平整度對(duì)瀝青面層的平整度影響可謂舉足輕重?；鶎拥氖┕げ牧现饕∮糜诋?dāng)?shù)?，在一個(gè)國(guó)家的不同地區(qū)所使用的材料的種類會(huì)有很大的變化。例如，基層可由礫石和碎石構(gòu)成或者是由經(jīng)過(guò)瀝青、水泥和石灰 /粉煤灰

9、等穩(wěn)定劑處理過(guò)的粒料所構(gòu)成。</p><p>　　由粒料或穩(wěn)定材料組成的底基層可以應(yīng)用于冰凍作用比較嚴(yán)重和路 基土承載力非常差的地區(qū)。從經(jīng)濟(jì)利益角度出發(fā)，它還應(yīng)用于那些底基層材料比優(yōu)質(zhì)的基層材料便宜的地區(qū)。</p><p>　　路基是基礎(chǔ)層，它必須承受作用在路面上的所有荷載。在某些情況下，路基7就是簡(jiǎn)單的天然土層。在其他或更多情況下，路基則是構(gòu)成路塹截面或路堤截面上層的壓實(shí)層。在柔性路面的

10、基本概念中，底基層(如果有的話)、基層、面層必須具有足夠的厚度來(lái)減小作用于路基上的應(yīng)力，避免使路基的士層產(chǎn)生過(guò)大的位移和變形。</p><p>　　影響柔性路面設(shè)計(jì)厚度的主要因素為：</p><p><b>　　(1) 交通荷載。</b></p><p><b>　　(2) 氣候或環(huán)境</b></p><

11、;p>　　(3) 材科特性。 </p><p>　　為了獲得最終的厚度設(shè)計(jì)結(jié)果，還必須考慮一些其他的因素，包括造價(jià)、施工、維修保養(yǎng)和設(shè)計(jì)期限。因此，學(xué)生們應(yīng)該認(rèn)識(shí)到設(shè)計(jì)過(guò)程是很復(fù)雜的，不可能有任何一種非常簡(jiǎn)單的方法來(lái)成功地解決處于不同條件下的所有問(wèn)題。</p><p>　　保護(hù)路基使其免受由交通運(yùn)輸量所產(chǎn)生的荷載的損傷是路面結(jié)構(gòu)層的一項(xiàng)主要功能。設(shè)計(jì)者還必須使所設(shè)計(jì)的路面能夠承受大量

12、的變化荷載的重復(fù)作用。</p><p>　　最大荷載的數(shù)值通常由法定的荷載限度來(lái)控制。通常通過(guò)交通量調(diào)查和輪載測(cè)定器來(lái)確定路面所承受的各種荷載的大小和出現(xiàn)頻率。對(duì)在路面的設(shè)計(jì)使用年限中交通量的預(yù)測(cè)和估算將是一項(xiàng)很艱難但顯然是很重要的工作。</p><p>　　氣候和環(huán)境因素對(duì)于柔性路面的路基、路面材料的使用性能會(huì)產(chǎn)生重要的影響。溫度和濕度可能是其中兩個(gè)最主要的氣候因素。 </p>

13、;<p>　　溫度的高低和變化影響著某些材料的性能。例如，瀝青混凝土在高溫時(shí)會(huì)喪失穩(wěn)性，而在低溫時(shí)，瀝青混凝上則會(huì)變得非常堅(jiān)硬。低溫和溫度變化還會(huì)導(dǎo)致凍脹和凍融 破壞。對(duì)子粒料，如果不采用合適的級(jí)配就會(huì)產(chǎn)生凍脹。同樣，處于凍結(jié)狀態(tài)中路基的強(qiáng)度也將大大降低。一些穩(wěn)定材料(經(jīng)過(guò)石灰、水泥和石灰/粉煤灰處理的) 如果經(jīng)過(guò)很多次的凍融循環(huán)作用就會(huì)遭受相當(dāng)大的損傷。 </p><p>　　濕度對(duì)很多種材料的性

14、質(zhì)和性能也有著重要的影響。在與冰凍有關(guān)的破壞中，濕度是一個(gè)重要的因素。飽和的地基土壤和其他筑路材料的強(qiáng)度會(huì)大大降低，某些黏土?xí)憩F(xiàn)出明顯的由水分所引起的體積變化。 </p><p>　　柔性路面平整度涉及的面很廣，影響因素很多，關(guān)系到路基、路面施工全過(guò)程，情況復(fù)雜，有的是機(jī)械性能引起，有的則是人為操作、安排失誤造成，我們只有在充分研究分析產(chǎn)生的原因后，才能對(duì)癥下藥抓好施工中的每一細(xì)小環(huán)節(jié)。瀝青路面平整度是施工機(jī)械

15、、人員素質(zhì)、操作水平的綜合反映，只有加強(qiáng)施工現(xiàn)場(chǎng)管理，精心組織施工，才能保證路面平整度，提高路面工程質(zhì)量。</p><p>　　Flexible Pavement Design</p><p>　　Generally speaking, pavements (and bases) may be divided into two broad classifications or types:

16、 rigid and flexible. As commonly used in the United States, the term “rigid pavement” is applied to wearing surfaces constructed of Portland-cement concrete. A constructed of concrete is assumed to possess considerable f

17、lexural strength that will permit it to act as a beam and allow it to bridge over minor irregularities which may occur in the base or subgrade on which it rests; hence the term “rigid</p><p>　　All other type

18、s of pavements have traditionally been classed as “flexible." A commonly used definition is that “a flexible pavement is a structure that maintains intimate contact will and distributes loads to the subgrade and dep

19、ends on aggregate interlock, particle friction, and cohesion for stability". Thus, the classical flexible pavement includes primarily those pavements that are composed of a series of granular layers topped by a rela

20、tively thin high-quality bituminous wearing surface. Typ</p><p>　　these pavements will be considered to be in the flexible class. In the construction of highway, because the pitch road surface has surface to

21、 levelled , drives a vehicle to resist the slippery , low in noise , short , characteristic of maintaining comfortably , wear-resistingly simply and conveniently etc. of cycle of constructing, and the extensive applicati

22、on of quilt. People go on the expressway by bus, the roughness can reflect the whole result after the expressway is open to the traffic dir</p><p>　　The structure of the flexible pavement is composed of a “w

23、earing surface," base, subbase (not always used), and subgrade. The wearing surface and the base often comprise two or more layers that are somewhat different in composition and that are put down in separate constru

24、ction operations. On many heavy-duty pavements, a subbase of select material is ofte placed between the base and subgrade. The wearing surface may range in thickness from less than 1 in. in the case of a bituminous surfa

25、ce trea</p><p>　　The base is a layer (or layers) of very high stability and density. Its principal purpose is to distribute or “spread” the stresses created by wheel loads acting on the wearing surface so th

26、at the stresses transmitted to the subgrade will not be sufficiently great to result in excessive deformation or displacement of that foundation layer. The base must also be of such character that it is not damaged by ca

27、pillary water and/or frost action. Old method on " basic unit level layer transfer , lower</p><p>　　A subbase of granular material or stabilized material may be used in areas where frost action is sever

28、e, in locations where the subgrade soil is extremely weak. It may also be used, in the interests of economy, in locations where suitable subbase materials are cheaper than base materials of higher quality. </p>&l

29、t;p>　　The subgrade is the foundation layer,the structure that must eventually support all the loads which come onto the pavement.In some cases this layer will simply be the natural earth surface. In other and more usu

30、al instances it will be compacted soil existing in a cut section or the upper layer of an embankment section. In the fundamental concept of the action of flexible pavements, the combined thickness of subbase (if used), b

31、ase,and wearing surface must be great enough to reduce the stresses o</p><p>　　The principal factors entering into the problem of the thickness design of flexible pavements are: </p><p>　　(1) Tr

32、affic loading. </p><p>　　(2) Climate or environment. </p><p>　　(3) Material characteristics. </p><p>　　A number of other elements must also be considered in order to arrive at a fin

33、al thickness design. These include cost, construction, maintenance, and design period. Thus,the students should realize that the design process is complex, and it is highly unlikely that any extremely simple method of ap

34、proach will prove entirely successful under all conditions.</p><p>　　Protection of the subgrade from the loading imposed by traffic is one of the primary functions of a pavement structure. The designer must

35、provide a pavement that can withstand a large number of repeated applications of variable-magnitude loadings. </p><p>　　The magnitude of maximum loading is commonly controlled by legal load limits.Traffic su

36、rveys and loadometer studies are often used to establish the relative magnitude and occurrence of the various loadings to which a pavement is subjected. Prediction or estimation of the total traffic that will use a pavem

37、ent during its design life is a very difficult but obviously important task.</p><p>　　The climate or environment in which a flexible pavement is to be established has an important influence on the behavior a

38、nd performance of the various materials in the pavement and subgrade. Probably the two climatic factors of major significance are temperature and moisture.</p><p>　　The magnitude of temperature and its fluct

39、uations affect the properties of certain materials. For example, high temperatures cause asphaltic concrete to lose stability whereas at low temperatures asphaltic concrete becomes very hard and stiff. Low temperature an

40、d temperature fluctuations are also associated with frost heave and freeze-thaw damage. Granular materials, if not properly graded, can experience frost heave. Likewise, the subgrade can exhibit extensive loss in strengt

41、h if it becomes fr</p><p>　　Moisture also has an important influence on the behavior and performance of many materials.Moisture is an important ingredient in frost-related damage. Subgrade soils and other pa

42、ying materials weaken appreciably when saturated, and certain clayey soils exhibit substantial moisture-induced volume change. </p><p>　　The surface that the roughness of road surface of flexible pavements i

43、nvolves is very wide, there are a lot of influence factors, concern the whole course of road bed , road surface construction, the situation is complicated, some are caused by the mechanical performance , some are the man

44、ual operation , arrange for the fault to cause, we only could suit the remedy to the case and do a good job of every tiny link while constructing after fully researching and analysing the reason produced . The </p>