桥梁裂缝产生原因浅析-毕业论文外文翻译

1、The bridge crack has the reason brief analysisAuthor: OrderIn recent years, our province transportation infrastructure obtained the swift and violent development, each place has constructed the massive concrete bridge. In the bridge construction and the use process, concerns because of appears the c

2、rack but to affect the project quality even to lead the report common occurence which the bridge breaks down collapses. The concrete dehiscence may say is "often is taken bad" and "frequently-occurring disease", is puzzling the bridge building technical personnel frequently. Actu

3、ally, if adopts the certain design and the construction measure, very many cracks are may overcome and control. In order to further strengthens to the concrete bridge crack understanding, avoids in the project appearing the harm big crack as far as possible, this article the reason which and produce

4、s to the concrete bridge crack type makes the comprehensive analysis, the summary as far as possible, by facilitates the design, the construction discovers the control crack the feasible means, achieves the guard in not however function .L concrete bridge crack type, originIn fact, the concrete stru

5、ctural cracks origin is complex and there are many kinds of factors, even they affect it mutually, but each crack has it to have one kind of or several kind of main reasons. The concrete bridge crack type,as the reason it produced, may divide the following several kinds approximately:First, the load

6、 causes crackThe concrete bridge is static in the convention, moves the crack which under the load and the secondary stress produces to call the load crack, induces mainly has the direct stress crack, the secondary stresscrack two kinds. The crack which outside the direct stress crack is refers to w

7、hich the load to cause the direct stress produces. The crack produces the reason includes:1st, design calculation stage, when structure computation does not calculate or partially leaks calculated; The computation model is unreasonable; Structure stress supposition and actual stress not symbol; The

8、load little calculated or leaks calculated; The endogenicforce with matches the muscle miscalculation; The structure safety coefficient is insufficient. When structural design does not consider the construction the possibility; The design cross section is insufficient; The steel bar establishment ar

9、e few or the arrangementmistake; The structure rigidity is insufficient; The structure processes is improper; The design paper confession is unclear and so2nd, the construction stage, does not limit piles up the construction machines1and tools, the material; Did not understand the prefabricated stru

10、cture structure stress characteristic, stands up from failure at will, the hoisting up, the transportation, the installment; According to the design paper construction, arbitrarily does notchange the structure construction order, the change structure stress pattern; Does not make under the machine v

11、ibration to the structure the fatigue strength checking calculation and so on.3rd, the operational phase, surpasses the design load the heavy vehicle bridge; Vehicles, ships contact, hit; Has the gale, the heavy snow, the earthquake, the detonation and so on.The secondary stress crack is refers to t

12、he secondary stress which causes by the outside load to produce the crack. The crack produces the reason includes:1st, outside design under load function, because the things the practical work condition same routine calculation has discrepancies or the computation considered, thus causes the seconda

13、ry stress in certain spots to cause the structure dehiscence. This place for example two articulations arched bridges skewback design often uses the arrangement "X" the shape steel bar, at the same time reduces the cross section size means design articulation, this place the theoretical ca

14、lculation can have the bending moment, but the actual this articulation still could anti- be curved, down to appeared the crack but to cause the steel bar to rust away.2nd, in the bridge structure needs the chisel groove frequently, opens the hole,the establishment corbel and so on, uses the accurat

15、e scheme in the routine calculation to carry on the analog computation with difficulty, the general basis experiences establishes the working reinforcement. The research indicated that, after the stress component digs the hole, the strength will flow has the diffraction, will be crowded nearby the h

16、ole, has the huge stress concentration. In long crosspre-stressedLiang, frequently in cross in needs to interrupt the steel continuously according to the section endogenic force to tie, establishment anchorage, but may see frequently nearby the anchor cross section to the crack. Therefore, if proces

17、ses improper, in these tructures corners or the component shape sudden change place, the working reinforcement cutoff is easy to appear the crack.In the actual project, the secondary stress crack has the load crack most common reason. The secondary stress crack is Zhang La, the cleavage, cuts the na

18、ture. The secondary stress crack also is causes by the load, only is does not calculate generally according to the convention, but along with the modern computation method unceasing consummation, the secondary stress crack also is may achieve the reasonable checking calculation. For example now to t

19、he pre-stressed, the continuous variation and so on two secondary stresses which produces, many plane links are the finite element procedure may correctly calculate, but quite is actually difficult in 40 years ago. In the design, should pay attention2avoids the structure changing suddenly (or cross

20、section sudden change), whencannot avoid, shouldmake partial processing, like the corner makes the fillet, thesuddenchange place makes changes gradually the transition, at the same timestrengthens the structure to match the muscle, the corner increases matches thediagonal steel bar, has side when th

21、e condition regarding the big hole may protectthe angle steel in the peripheralestablishment.The load crack characteristic is differentdifferently but accordingto the loadpresents the different characteristic. This kind of crack appears is receiving pulls thearea, is cut the area or the vibration se

22、rious spot. But must point out, if thecompression zone appears the skin or has along the bearing direction short crack,often is the structure achieved the supporting capacity limit the symbol, is thedisarrangement of the structure omen, its reason often is the section size is small.According to the

23、structure different stress way, the crack characteristic whichproduces as follows:1st, the center is pulled. The crack passes through the component lateral section,the spacing is roughly equal, also is vertical to the stress direction. When uses thethread steel bar, between the crack appears is loca

24、ted nearby the steel bar the inferiorcrack.2nd, central bearing. Appears along the component is parallel is short but thedense parallel crack in the stress direction3rd, when it is bent. Nearby the bending moment biggest section from receivespulls the area border to start to appear with is pulled th

25、e direction vertical crack, anddevelops gradually to the neutral axis direction. When uses the thread steel bar,between crack obviously short inferior crack. When the structure matches themuscle to compare the youth, the crack are few but extends, the structure possiblyhas the brittle destruction.4t

26、h, big eccentric compression. The big eccentric compression and is pulled thearea to match the muscle few small eccentric compression component, is similar inreceives bends the component.5th, small eccentric compression. The small eccentric compression and ispulled the area to match the muscle many

27、big eccentric compression component, issimilar in the center compressional member.6th, is cut. When the stirrup too is dense has the slanting pressure destruction,appears along the Liang end abdomen is bigger than 45the direction °slanting crack;When the stirrup is suitable occurs cuts presses

28、the destruction, appearsapproximately 45°the direction mutuallyparallel slanting crackalong LiangDuanzhong lower part.7th, is turned. A component side abdomen appears the multi- treaties 45 side°3syncline crack first, and launches to the neighboring surface by the spiral direction. 8th, di

29、e cutting. Four sides have approximately 45 the direction incline° tensionfracture along the column head plate in, forms flushes the section.9th, partial bearing. Appears in the partial compression zone with the pressure direction approximately parallel multi- strip short crack. Second, the tem

30、perature change causes crackSecond, the foundation distortion causes crackBecause the foundation vertical differential settlement or the horizontal direction move, causesin the structure to have the additional stress, surpassesthe concrete structure anti- to pull the ability, causes the structure de

31、hiscence. The foundation differential settlement main reason includes:1st, the geological prospecting precision is insufficient, the experimental material does not permit. In not fully keeps abreast of the geological situation on the design, the construction, this is creates the ground differential

32、settlement the main reason. For instance rolling country or mountain ridge area bridge, when reconnaissance drill hole spacing too far, but the bedrock surface fluctuation also is big, the reconnaissance reported cannot fully reflect the actual geological situation.2nd, the ground geology difference

33、 too is big. The construction in the mountainous area run-off ditch bridge, the brook place geology and the hillside place change is big, in the brook even has the weak subgrade, the foundation soil because the different compression causes the differential settlement.3rd, the structure load differen

34、ce too is big. When geological situation quite consistent condition, each part of foundations load difference too big, has the possibility to cause the differential settlement, for example middle the high earth fill box culvert hole must be bigger than two side load, the middle subsidence must be bi

35、gger than two nearby, the slab culvert possibly cracks.4th, the structure foundation type difference is big. In the identical joint bridge, the mix use different foundation like expansion foundation and the pile foundation, either at the same time use the pile foundation when the pile diameter or th

36、e pile long difference big, or at the same time uses the expanded foundation when the basis elevation difference is big, also possibly causes the ground differential settlement.5th, constructs by stages foundation. When original bridge foundation newly built bridge, like constructs by stages about h

37、ighway half bridge, when newly built bridge load or foundation treatment causes the foundation soil reto solidify, possibly creates to the original bridge foundation subsides greatly.6th, ground heave. In is lower than the zero degree under the condition the moisture content high foundation soil bec

38、ause to freeze the inflation; Once the temperature rise, the frozen earth melts, the ground sinks. Therefore the ground4freezes or the melting may create the differential settlement.7th,when the bridge foundation puts in the landslide body, the limestone cave or the moving fault and so on not the go

39、od geology, possibly creates the differential settlement.8th,after the bridge completes, original ground condition change. After the majority natural foundation and the artificial ground immerse, the element earth fill, the loess, the inflation earth and so on the special foundation soil, the soil b

40、ody intensity meets the water to drop in particular, the compression deformation enlarges. In causes the subsoil water level to drop, the ground soil layer resolidifies sinks, at the same time reduces to the foundation buoyancy, the negative friction increases, the foundation is enlarged Holland. So

41、me bridges foundation embedment excessively is shallow, is washed out the flood, washes digs, the foundation possibly moves. Theground load condition change, like the bridge attaches the immediate cause landslide, reason and so on mountain body landslide piles sets at the massive waste sides, the sa

42、nd and crushed stone and so on, the bridge site scope soil layer possibly receives compresses distorts once more. Therefore, the use period original ground condition change possibly creates the differential settlement. And so on produces horizontal thrust the things regarding the arched bridge, gras

43、ped to the geological situation insufficient, the design was unreasonable and when the construction destroyed the original geological condition has the horizontal departure crack main reason.Third, the steel bar rusts away the crack which causesBecause the concrete quality misses or the protector th

44、ickness insufficient, the concrete protector is carbonized the carbon dioxide corrosion to the steel bar surface, causesaround the steel bar the concrete alkalinity to reduce, or as a result of the chloride involvement, around the steel bar the chloride ion content is high, may cause the steel bar s

45、urface oxide film to destroy, in the steel bar the hard ion with invades the oxygen and the moisture content occurs to the concrete in rusts away the response, it rusting away hydroxide of iron volume doubles approximately compared to original growth 24, thus has the inflation stress to the peripher

46、y concrete, causes the protector concrete dehiscence, to strip, longitudinal produces the crack along the steel bar, and has the rusty stain to infiltrate to the concrete surface. Because rusts away, causes the steel bar effective section area to reduce, the steel bar and the concrete grasp binds th

47、e strength to weaken, the structuresupportingcapacity drops, and will induce other forms the crack, willintensifythe steel bar to rust away, causes the disarrangement of the structure.Must prevent the steel bar rusts away, when design should according to the standard request control crack opening, u

48、se the enough protector thickness (natural protector also not5to be able too to be thick, otherwise component effective height reduces, when stress will enlarge crack opening); When construction should control the concrete the water ratio, strengthens inspires pounds, guaranteed the concrete the den

49、sity, prevented the oxygen invasion, at the same time the strict control contains the chlorine salt the sur- medicinal preparation amount used, the coastal area or other existence corrosiveness strong air, the ground water area should be prudent especially.Fourth, the heave causes crackWhen the atmo

50、spheric temperature is lower than the zero degree, absorbs water the saturated concrete to appear freezes, the water which drifts away transforms the ice, the volume expansion 9%, thus the concrete has the inflation stress; At the same time in theconcrete gelatin hole cold water (has iced up tempera

51、ture below -78) the migration and the heavy distribution causes the osmotic pressure in the microscopic structure, causes in the concrete the expansive power to enlarge, the concrete intensity reduces, and causes the crack appearance. At the beginning of the concrete congeals in particular when is f

52、rozen seriously, Cheng Linghou the concrete intensity loses may reach 30%50%. When winter construction is in the milk after the pre-stressed passageway if does not take the heat preservation measurealso possibly to occur along the pipeline direction heave crack.The temperature is lower than the zero

53、 degree and concrete absorbing water is saturated has the essential condition which the heave destroys. When in the concrete the aggregate crevice are many, hygroscopicity; In the aggregate contains impurity and so on soil excessively are many; The concrete water ratio is big, inspires pounds not de

54、nsely; Maintains the strength not to cause the concrete early time to freeze and so on, possibly causes the concrete heave crack.When winter construction, uses the electrical heating, the warm awning law, the underground thermos method, the steam heating maintains as well as mixes up in the water in

55、 the concrete to mix in the antifreeze (but chlorine salt not suitably to use), may guarantee the concrete or under the negative warm condition hardens in the low temperature.Seventh, the construction material quality causes crackThe concrete mainly by the cement, the granulated substance, the aggre

56、gate, mixes up the water and the sur- medicinal preparation is composed. The disposition concrete uses the material quality not to be unqualified, possibly causes the structure to appear the crack.6桥梁裂缝产生原因浅析作者：秩名近年来，我省交通基础建设得到迅猛发展，各地兴建了大量的混凝土桥梁。在桥梁建造和使用过程中，有关因出现裂缝而影响工程质量甚至导桥梁垮塌的报道屡见不鲜。混凝土开裂可以说是“常发病

57、”和“多发病”，经常困扰着桥梁工程技术人员。其实，如果采取一定的设计和施工措施，很多裂缝是可以克服和控制的。为了进一步加强对混凝土桥梁裂缝的认识，尽量避免工程中出现危害较大的裂缝，本文尽可能对混凝土桥梁裂缝的种类和产生的原因作较全面的分析、总结，以方便设计、施工找出控制裂缝的可行办法，达到防范于未然的作用。l 混凝土桥梁裂缝种类、成因实际上，混凝土结构裂缝的成因复杂而繁多，甚至多种因素相互影响，但每一条裂缝均有其产生的一种或几种主要原因。混凝土桥梁裂缝的种类，就其产生的原因，大致可划分如下几种：一、荷载引起的裂缝混凝土桥梁在常规静、动荷载及次应力下产生的裂缝称荷载裂缝，归纳起来主要有直接应力裂缝、次应力裂缝两种。直接应力裂缝是指外荷载引起的直接应力产生的裂缝。裂缝产生的原因有：1、 设计计算阶段，结构计算时不计算或部分漏算；计算模型不合理；结构受力假设与实际受力不符；荷载少算或漏算；内力与配筋计算错误；结构安全系数不够。结构设计时不考虑施工的可能性；设计断面不足；钢筋设置偏少或布置错误；结构刚度不足；构造处理不当；设计图纸交代不清等。2、 施工阶段，不加限制地堆放施工机具、材料；不了解预制结构结构受力特点，随意翻身、起吊、运输