土木工程建筑道桥外文翻译外文文献英文文献沥青路面结构设计的低成本农村道路

1、外文文献 structural design of asphalt pavement for low cost rural roadsyuan goulin(袁国林)12 chen rongshen(陈荣生)1. college of transportation, southeast university, nanjing 210b9b, china2. college of civil engineering, nanjing university of technology, nanjing , china in developing countries，rural road const

2、ruction is mostly cumbered by shortage of funds. engineers concerns most in rural areas is how to build roads which not only cost less but also meet the traffic demands. especially in vast rural areas of china, there are a great variety of transportation patterns, and the traffic composition is very

3、 complex. compared with other countries，the traffic composition in china rural areas have its own features. therefore，there is no experience about the rural roads construction for reference. in recent years，the central government of china has increased the strength for rural road construction. at th

4、e same time，a lot of researches about rural road construction have been done by researchers in china, and some conclusions about china rural roads have been made. in the authors opinion，the selection of the pavement structure material is the key measure to reduce the construction cost of rural roads

5、 after the route has been determined. compared with concrete pavement，asphalt pavement relatively costs less and is the first choice for rural roads in china. and then，according to the research achievements about rural roads construction，the authors have done some preliminary researches on the struc

6、ture design for low-cost asphalt pavements for rural roads.1 traffic composition of rural road rural roads include county roads，town roads and village roads. the traffic on rural roads is usually mixed. on a county road, traffic volume is between 300 to 1500 veh/d in average，and in a county with a d

7、eveloped economy，it reaches 1000 to 2 000 veh/d. the traffic volume between county and town is 100 to 300 veh/d，and the traffic volume between towns is usually less than 100 to 300 veh/d. in a mixed traffic flow，trucks account for 40% to 70% of the traffic volume, which are mainly light trucks carry

8、ing less than 2. 5 tons(including agricultural vehicles such as electro-tricycles，walking tractors etc.)and medium-size trucks of 2. 5 to 5 tons. most of these light or medium trucks are overloaded. the proportion of heavy truck is less than 9%.on some roads to counties，the proportion of overloaded

9、trucks is 5% to 32 %，while on some county roads connecting to national or provincial trunk highways，the proportion of overloaded vehicles usually amounts to 20% to 32% .the traffic volume on rural roads is not heavy. however，considering the practical situation in china, as well as the exitence of ov

10、erloaded vehicles，100kn，or bzz-100 was adopted as standard axle load in the research. the pavement deflection or the flexural-tensile stress at the bottom of asphalt surface is taken as the design parameter. the axle load was calculated inaccordance with the following formula:pi和ni-the axle weight o

11、f an i-level axle in kn and the action frequency;ns和ps-the axle weight of standard axle in 100 kn and the action frequency;if the distance between axles is less than 3 m， axle loads are calculated asa double-axle or multi-axle loads，andc1=1+1.2m-1if the flexural-tensile stress at the bottom of semi-

12、rigid base is taken as the design parameter, the axle load is calculated in accordance with the following formula:nsni=c1c2pips8if the distance between axles is less than 3m，c1=1+2(m-1)2 traffic volume on rural roads minibuses are adopted as the standard vehicle for the design of rural roads. table

13、1 shows its external dimensions.table 1 external dimensions of the passenger car mlength width height front overhang distance between axles rear overhang 6.0 1.8 2.0 0.8 3.8 1.4 the typical vehicle types on rural roads are listed in table 2. and others such as non-power-driven vehicles，animal-drawn

14、vehicles，and bicycles can be taken into account in the calculation of traffic volume on rural roads，in view of their roadside interference. in accordance with the traffic composition and volumes，rural roads are divided into five grades. the traffic volume of each grade is shown in table 3. traffic v

15、olume specified in table 3 was obtained by taking the minibus as the standard vehicle type,and converting different types vehicles according to the vehicle conversion coefficients given in table 2.in table 3， ne refers to the cumulative equivalent axle load action frequency; ns refers to the equival

16、ent axle load action frequency in the designed traffic lane in the beginning operation period of rural roads; y refers to the average annual growth rate of traffic volume; refers to lane coefficient, and 1.0 for a single lane and 0. 6一0. 7 for a dual lane.3 strength of roadbedthe modulus of resilien

17、ce of roadbed varies greatly. for convenience，the strength of roadbed can be divided into four classes according to its moisture content and modulus of resilience，as shown in table 4. the parameters in table 5 are determined by combining design principles with practical experience. by applying elast

18、ic multilayer theory to the pavement structure specified in table 5，the influence of ne on the pavement thickness of rural roads was analyzed，and the result show that for given h，h2，e0，the roadbase thickness for neighboring traffic classes changes in a range of 4-5 cm. this result indicates that the

19、 classification of traffic volume on rural roads shown in table 3 is reasonable and feasible in terms of the design and construction of asphalt pavement structures. by using the elastic multilayer theory，the asphalt pavement structure of ordinary rural road in table 5 is analyzed. when ne，the cumula

20、tive equivalent axle load action frequency，the thickness of road surface(h =3 cm)，and the thickness of subbase(h2 = 20 cm ) remain the same , the influence of neighboring roadbed strength classifications on the thickness of roadbase is 3 cm一5 cm. this conclusion indicates that the strength classific

21、ation of roadbed is reasonable and applicable to the design and construction of asphalt pavement structure.4 determination of thicknesses of asphalt pavement structure sensitivity analysis of the design parameters of roadbed and pavement structures is to find out the relationship between structural

22、strength of asphalt pavement structure and the design parameters of each layer, and determine the most sensitive layer in the pavement structure. the asphalt pavement structure of rural roads is generally composed of a road surface, a roadbase，and a subbase，as shown in table 6. the pavement structur

23、e was analyzed according to elastic multiplayer theory under the double circular uniform load，with an assumption that there is continuous contact between the adjacent layers of the asphalt pavement structure. the basic parameters used in the calculation and analysis of asphalt pavement structure are

24、 listed in table 7. by analyzing the effects of the change of all the parameters of pavement structure on the distortion of the road surface，roadbase，and roadbed , the following conclusions have been drawn.(1)increasing the thickness of the road surface effectively decreases the road surface deflect

25、ion，but raises the cost. the comparatively economical and effective method is to increase the thickness of the subbase, which is superior to increasing the thickness of roadbase，while increasing the thickness of the road surface is the last choice.(2)as the thickness of pavement structure increases，

26、the change of road surface deflection will trend to be gentle. when the thickness of road surface reaches a certain value，the variance in the road surface deflection will not be obvious，and then it is ineffective to enhance the bearing capacity of asphalt pavement structure by increasing the thickne

27、ss of road surface. it is recommended that the thicknesses of the roadbase and the subbase should be equal to or largerthan 18 and 20 cm, respectively，in design of asphalt pavement structures of rural roads. fig. 1 shows the effects of the changes in the thickness of each layer on road surface defle

28、ction.(3)road surface deflection is very sensitive to the change of modulus of the roadbed. the increase in the modulus of roadbase or subbase is also effective to decrease the deflection of the road surface. on the other hand，the deflection of the road surface decreases gradually when the modulus o

29、f the surface increases，being the least effective factor. when the modulus of the road surface increases to a certain value， decrease in road surface deflection is not apparent. fig. 2 shows the effect of the modulus of each layer on road surface deflection. from the above discussion，we conclude tha

30、t the most sensitive layer for road surface deflection is subbase，and the next is roadbase. to decrease the road surface deflection of low-cost rural roads，the strength and stability of the roadbed should be enhanced, and the materials with a certain thickness and relatively high density should be u

31、sed to pave the subbase. the traffic volume or the accumulative equivalent axle load action times(frequency)within the designed life of road is used to determine the type and thickness of the asphalt pavement road surface, and the results are listed in table 8，where veh/d means the number of the equ

32、ivalent the passenger cars per day. for a low traffic volume rural road with ne 500 000，graded broken stones(or gravel)can be used as a flexible base. the flexible base has good strength and effectively prevents reflection cracks of the asphalt pavement road surface, provided the graded broken stone

33、s(or gravel ) meets the requirements for high density(degree of compaction ,100%. to ensure the sufficient strength and stability of the flexible base，its thickness is not less than 15 cm，the thickness of the aggregate subbase is not less than 20 cm，a semi-rigid base usually has a good bearing capac

34、ity for the rural roads with ne)500 000，or those with low traffic volumes but relatively,the minimum thickness of semirigid base or subbase is 16-18 cm5 calculation of the thickness of road surface5.1 deflection(1)road surface deflection road surface deflection is a vertical distortion caused by ver

35、tical load on the road surface. it not only reflects the whole strength and stiffness of asphalt pavement structure and roadbed，but also has a close internal relation with the service condition of the pavement.(2)design deflection the design deflection is the index representing the stiffness of the

36、pavement structure. it is also the deflection of the pavement which is established according to the accumulative equivalent axle load estimated to pass over a lane in the expected design life, road types, road classification，and the types of road surface and roadbase. the design deflection is not on

37、ly the main basis for the design thickness of the pavement structure，but also the necessary index for the examination and acceptance of the project. through theoretical analysis and experimental study，formulas for the design deflection value which are applicable to the pavement structure design of l

38、owcost rural roads are as follows:semi-rigid base:ld=629ne-0.2asflexible base:ld=1134ne-0.2aswhere a, is the type coefficient of the road surface. the type coefficient of asphalt concrete road surface is 1.0;that of hot-mix asphalt macadam and that of emulsified asphalt macadam road surface are all

39、1. 1; and that of asphalt surface treatment road surface is1 .2.(3)allowable deflection allowable deflection is the maximum deflectionallowed at the end of the roads service life under lim-iting conditions in poor season. through thoreticalanalysis and experimental study，the calculation for-mulas fo

40、r the allowable deflection of road surfacewhich are applicable to the pavement structure designof low-cost rural roads are as follows2:ld=786ne-0.2asld=1418ne-0.2aswhen designing the asphalt pavement structure of low-cost rural roads, we should use formula (6) or (7 ) according to the types of roadb

41、ase to determine the thickness of asphalt pavement structure.5.2 tensile stress because the asphalt pavement structure of lowcost rural roads is not substantial enough and the heavy vehicles are allowed to pass over them, the maximum tensile stress should be checked by computing the stresses of the

42、semi-rigid base and subbase. the tensile stress at the bottom of semi-rigid base or subbase，would be less than or equivalent to the allowable tensile stress of the materials of the semirigid base or subbase , namely，mr=spksfor the stabilized aggregate base with an inorganic binder-ks=0.35ne0.11ac,ac

43、=1.2for the stabilized fine-grained soil base with an inorganic binder:ks=0.35ne0.11ac,ac=1.25.3 pavement thickness to make it simple and convenient for engineers to determine the desired thickness of rural road pavement, the curves of the thickness of the roadbase of low-cost rural roads according

44、to typical pavement structures and accumulative frequency of equivalent axle load are shown in figs. 3，4 and 5. (1)when the accumulative frequency of equivalent axle load is within times per lane，asphalttreated or asphalt penetrated surfaces with thickness of 1. 5 cm一cm is recommended for road surfa

45、ce. for various accumulative equivalent axle loads and the moduli(eo)of roadbed，the equivalent thickness of roadbase is shown in fig. 3.(2)when the accumulative frequency of equivalent axle load is within 500 001)一1 000 000 times per lane，asphalt macadam or asphalt concrete with thickness of 3 cm -5

46、 cm is recommended. for various accumulative equivalent axle loads and moduli(eo)of roadbed，the equivalent thickness of roadbase is shown in fig. 4.(3)when the accumulative frequency of equivalent axle load is within 1000 000-2 000 000 times per lane，asphalt concrete road surface of 5 cm-7 cm thick

47、is recommended. for various accumulative equivalent axle loads and moduli(eo)of roadbed , the equivalent thickness of roadbase is shown in fig.s.in figs.3-5，ld is the designed deflection, lo is the representative deflection of roadbed，e, is the modulus of resilience of the roadbase，in mpa , eo is th

48、e modulus of resilience of the roadbed，in mpa ,and h, in cm，is the equivalent thickness of the base (roadbase and subbase)，which can be obtained through calculation and in-site investigation for a trilevel-pavement roads(including road surface，base and roadbed).if a designed road has four layers，i.e

49、. a subbase is added，according to the regression analysis of the extrapolated results of a number of multi-layer flexible systems and the available research findings，the thickness of the roadbase , h,，in cm, can be calculated from the following equation:h1=h-h22.4e2e16 concluding remarks compared wi

50、th concrete pavement, asphalt pavements have a lower construction cost, which is suitable for the roads in relatively underdeveloped rural areas in china. the research in this paper proposed a method for structural design of low cost asphalt pavements. the method is to provide an guideline for the d

51、esign of asphalt pavement structure in rural areas.references1yuan g l , zhang f , chen s w , et al. research on technical indexes of rural highway construction in jiangsu province j .highway, 2005(6):135一139(in chinese). 2 research institute of highway , the ministry of communications. final report

52、 on low cost inter-township and rural road construction techniquesr.beijing; resdarch institute of highway, 2003(in chinese). 3 liu q q. how to reduce the construction cost of the rural highway j .journal of highway and transportation research and development, 2005(2):41一44(in chinese). 4 jtg b014-9

53、7. specification for design of highway asphalt pavement s (in chinese ). 5 jtg bo1-2003. technical standard of highway engineering s (in chinese).6 deng x j. engineering for sub-grade and pavement m.2nd ed. beijing; peoples communications press, beijing, 2004(in chinese ).中文译文沥青路面结构设计的低成本农村道路袁国林1，陈荣

54、生21。交通运输学院，东南大学，南京210b9b，中国2。土木工程学院，南京工业大学，南京，中国在发展中国家,农村道路建设主要是因缺乏资金而受阻。工程师最关心的农村问题是如何修建的公路不仅成本低,而且满足交通需求。特别是在广大农村地区,有各种各样的交通方式,交通成分非常复杂。与其他国家相比,在中国农村地区交通组成有其自身的特征. 因此,没有足够经验对农村公路建设提供参考依据。近年来,中国的中央政府增加了对农村公路建设的力量。与此同时, 在中国，研究人员已经完成了关于中国农村道路的大量研究和一些结论。在作者的观点,选择不同的路面结构材料是关键措施，从而降低农村道路的工程造价。相比,沥青混凝土路面

55、相对费用少、是第一个在中国农村道路的选择。然后,根据农村道路建设研究成果,作者也做了一些对低成本沥青路面结构设计的初步研究。1 农村道路交通组成 农村道路包括县公路、城市道路和村的道路。 农村道路上，交通通常是喜忧参半。一个平常县的道路，交通量平均为的300至1500辆/ 天；一个经济发达的县,已经达到了1000到2000 辆/ 天。通信量县、镇之间是100到300辆/ 天，交通量之间通常低于城镇是100至300辆/ 天。在一个混合交通流、卡车占有40%到70%的交通量,主要为轻型卡车携带小于2.5吨(包括农业车辆如拖拉机等)、行走、中型卡车2.5 - 5吨。大部分的轻或中等卡车超载。重型卡车

56、的比例小于9%。某些道路上的比例对县、超载的卡车是5%至32%,而在一些县公路连接到国家或省级公路的比例躯干,超载的比例通常数量的20%提高到32%。 交通量对农村道路不会很重。然而,考虑到中国的实际情况,以及车辆超载,要满足 100 kn,和 bzz-100标准轴载作用次数。人行道挠度和底部的拉应力作为沥青路面设计参数。轴载荷计算方式,依照下面的公式:pi和ni为车轴重量和频率ns和ps为总车轴重量和频数如果两轴之间的距离小于3米,轴载荷进行了计算：c1=1+1.2m-1如果弯拉型压力的半刚性基层底部作为设计参数计算、轴重依下列公式：nsni=c1c2pips8如果两轴之间的距离小于3米：c

57、1=1+2(m-1)2 对农村公路交通量 农村道路以面包车为车辆的设计标准。表1显示了其外部尺寸。典型的车辆类型农村道路都列在表2。如电动车,摩托车 和自行车可以考虑为边对农村道路交通量的计算的路边干扰。根据交通组成和卷,农村道路被分成5个等级。每一等级通信量见表3。交通量在表3规定经以小巴为标准的车辆类型,并将不同类型车辆的车辆折算系数记录在所给的表2，表3中,ne指的是累积的等效轴重行动的频率ns指的等效轴重行动的频率在设计交通车道上开始运行期间;r指的年增长率交通量指系数,一个车道为为1.0,双车道为0.6一0.7。3路基强度路基回弹模量的变化极大。为方便起见,路基的强度可以分为四类根据

58、其含水率和模量的韧性,显示在表4。表5的参数确定设计原则相结合的实践经验。采用多层弹性理论对路面结构表5中指定的影响,在暗夜精灵,农村道路铺装厚度进行了分析,结果表明,在给定的h,h2,e0、路面基层厚度变化为周边交通类一个范围内的4 - 5厘米。测试结果表明,该分类农村道路运输量对显示在表3是合理的、可行的设计和施工条件对沥青路面结构。采用多层弹性理论,沥青路面结构的普通乡村公路表5中进行了分析。当北东向、累积的等效轴重行动频率,路面的厚度(h = 3厘米的厚度)、基层(h2 = 20厘米)保持不变,邻近的路基强度的影响分类基层的厚度为3 cm一5厘米。这一结论表明,路基强度分类是合理的、适用于设计与施工的沥青路面结构。4厚度测定沥青路面结构设计参数的灵敏度分析路基和路面结构之