CN85105302A - Improved flexible pavement - Google Patents
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- CN85105302A CN85105302A CN85105302.5A CN85105302A CN85105302A CN 85105302 A CN85105302 A CN 85105302A CN 85105302 A CN85105302 A CN 85105302A CN 85105302 A CN85105302 A CN 85105302A
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Abstract
A kind of asphalt pavement structure cross section is the distribution of various material layers.The effect of the radiation propagation of body force has been played in its distribution.These layers distribute by the order of selecting in advance, from the roadbed to the upper surface.Near on the base course, has ultimate tensile strength.
Description
The present invention relates to carry road surface and construction thereof, further relevant with improved high-quality asphalt road surface.
The high-quality asphalt road surface has multiple important use, and for example, it is used for automobile and the truck flow is big, the speedway of heavy traffic.The aircraft takeoffs and landings sortie is frequent, very big runway and the taxiway of loading, and the harbour construction of container cargo storing loading and unloading.
Here employed high-quality asphalt road surface is meant main flexible pavement with high-quality constructional materials making.This high-quality constructional materials can only and use special-purpose making equipment construction by the central factory processing and manufacturing usually.This has just guaranteed that different pavements rationally is compacted equably.Pavement is suitable layer, grating and thickness, has guaranteed that the topmost surface layer is uniform and smooth, to guarantee the safety traffic of rapid transit vehicle.
Can be classified as flexible paver class with material rigidity or that portland cement concrete pavement comparison bituminous concrete is paved the way, two kinds of basic flexible pavements are layering, individual layer pitch pavement, individual layer pitch pavement only is made of the dense-graded asphalt concrete that directly is layered on the ground, in the layering flexible pavement, optimum material making is at that one deck on approaching surface, these materials are pressed its probably sequence of positions in structural section, from roadbed.Comprise soil, woollen stone, finished stone, pipeline and concrete crushed stone piece and bituminous concrete, stabilometer measured value and stone equivalence factor are still the numerical Evaluation mass parameter, though admitted in recent years, bituminous concrete has the characteristic on some structural concrete road surface.
The method and the mechanical means of experiment all are applied on the Flexible Pavement Design at present.Index parameters is through being commonly used to illustrate pavement, roadbed characteristic and communications and transportation.The pavement series of strata generally meet the preparation of prior art design basic principle, the mutation of included above-mentioned Reference Design at U.S. Patent number Travilla a.936,493, Davis 984801.Done explanation among U.S. Patent number Ebberts etal 2083900 and the Sommer3044373.
Method for designing is experimentally utilized pavement thickness of section and the communications and transportation of being planned and is reproduced design equation and a series of chart that subgrade soil intensity interrelates, the performance of communications and transportation and pavement is generally combined, equivalent material thickness factor can be in order to the replacement foundation of structural section material, employed equivalence factor is different because of special method for designing, but when the aggregate base was replaced dense-graded asphalt concrete, thickness reduced 40%-60%.
The designing technique of foundation that early stage with the experiment is is to be designed program and obtained using in several western countries by the stabilometer of California, USA exploitation, recently, more advanced method is American States highway worker association (old) soft pavement design method (AASHO).
The machine design method on road surface is partly set up on the mechanical foundation, and is foundation with the analytical technology of generally acknowledging.In Machine Design, road surface series of strata internal stress strain field obtains differentiating that the road surface cross section property obtains specifically describing, and reasonably characteristic description must reflect temperature and cut lotus speed to bituminous concrete toughness and Fatigue Life.Stress state is to the influence of the bituminous concrete toughness of aggregate base and Song Jipei, and stress state and water capacity are for the toughness of subgrade soil and the influence of permanent deformation.
The evaluation of stress-strain field is finished by means of the elastic constants elasticity stratification computer code compatible with rate of loading, temperature, stress state and humidity usually, operable technology reflection in modern age stress state is for the influence of elastic constants, and the temperature and humidity field of Computer Analysis can help to select to be fit to this elastic constants of reflection environmental factor.
The evaluation of Machine Design is to compare by strain that critical zone (being muddy degree) structural section is designed and predetermined material failure criteria to finish.When the constructional materials and make when understanding in depth for the mechanical features of certain meaning of cutting the lotus response of paving the way to common use, according to the amount that common material meets with stresses, prior art just can not utilize knowledge to obtain best series of strata.(that is: road structure).Therefore, effectively mechanics method analytical technology in the past just can not be from the pavement design of the new the best of principle generation.
The present invention proposes and has overcome above-mentioned and other shortcoming of prior art, the pitch floor file structural section that covers ground is provided on the one hand, and structural section comprises multilayer material, and this layer is arranged with selected order, from ground to the upper space, the layer that tensile strength is the highest is arranged in and closes on roadbed.
On the other hand, the present invention comprises improving one's methods of a kind of asphalt pavement structure cross section, and this method comprises arranges the multilayer material step, so that when having only compressive stress or pulling force to hold to cut, makes basically and cuts a lotus and spread all over each layer.
Above-mentioned and other characteristics of the present invention and advantage are further illustrated in the detailed explanation in the most preferred embodiment in the back.A series of charts are arranged, wherein digital details in this explanation corresponding to whole invention.
Fig. 1 is the road surface sectional drawing according to improvement pitch of the present invention;
Fig. 2 is the sectional drawing according to the individual layer pitch pavement structural section of prior art;
Fig. 3 is the sectional drawing according to the sandwich construction cross section of prior art;
Fig. 4 is the road structure model that is shown in the prior art of prior figures 3.
(Fig. 5 (a) and 5(b) be the stress diagram on Fig. 3 prior art road surface under a wheel and two wheel loads respectively.
Fig. 6 illustrates the typical fracture by fatigue relation of close-graded concrete.
Fig. 7 has represented the functional relation of close-graded pitch young's modulus of elasticity to carrying time and mixing temperature.
Fig. 8 has represented the functional relation of the poisson's ratio counter stress of dense-graded aggregate.
Fig. 9 is that semilog plot has shown vertical stress and cut the loading relation between the number now.
Figure 10 (a) and 10(b) stress diagraies on road surface of the present invention when being the carrying of a wheel and two wheel respectively;
Figure 11 has represented the functional relation of stretching strain to bituminous concrete layer thickness of the present invention.
The functional relation of cost per unit when Figure 12 has represented critical stretching strain;
Figure 13 has represented the functional relation of critical pressure strain to cost per unit.
Translate among the figure, Fig. 1 is that section of structure comprises the predetermined arrangement layer that the roadbed after smooth 12 is covered according to the drawing in side sectional elevation of improvement asphalt pavement structure knot face of the present invention.
The arrangement that is made of the present invention comprises 1/2～2 inch thick surface course 14.Presentation layer 14 is close to graded aggregate 16 supportings, and it covers again on the loose graded aggregate layer 18, and loose graded aggregate layer 18 making are on the top of improved close-graded concrete base 20.
Smooth wear-resistant non skid matting layer 14 can be a dense-graded asphalt concrete, pine grating bituminous concrete or surfacing, in using close-graded or loose grating bituminous concrete, it generally will be thicker requiring layer 14 according to making, and this is to produce one 3/8 inches thin layers because single asphalt surface is handled.Under person's situation, the thickness of layer 14 depends on the surface-treated number of times and use the size of stone in processing procedure.Using the single surfacing of 1/2 or 3/8 inch maximum stone, is suitable for most application.Selected loose grating bituminous concrete is spread multiple and compacting by the above-mentioned standardization program of discussing traditionally.Follow making again, the intensive asphalt concrete layer of joining commonly used, as shown in dense-graded aggregate layer 16 be not a kind of primary structure material, it mainly plays the multiple effect on it in surface course 14 easier shops that makes, be understood that layer 16 has indefinite rigidity, so that the traffic volume that support matrix surface layer 14 is born.
Pine graded aggregate layer 18 is the crushed stone of maximum gauge single-size between 1～2 inch basically, has less than 2%～3% and can lead to sieve No. 200.The construction (promptly sprawling and compacting) of layer 18 is identical with the construction of dense-graded aggregate basically, and majority utilizes road roller to 16 compacting of dense-graded aggregate layer.
The construction that improves dense-graded asphalt concrete layer 20 is substantially similar to the construction of dense-graded asphalt concrete commonly used, improving layer is different, rationally mixture experiment design can be utilized higher viscosity tarmac cement and utilize its bitumen content of bitumen content (about 0.5%～1.5%) at the overgauge dense-graded asphalt concrete greater than the prior art dense-graded asphalt concrete, consider the stone grade, construction changes definite content according to standard engineering).In addition, layer 20 can be built under highly dense solidity, and it has high tenacity with the high asphalt cement of degree, high fatigue life and very low transmissibility.
Fig. 2 and Fig. 3 are the drawings in side sectional elevation according to the asphalt concrete pavement commonly used of prior art.Illustrate disclosed commonly used monolayer asphalt concrete road surface among Fig. 2, it is to be made of single concrete or the close-graded bitumen layer 22 that covers roadbed 24.Fig. 3 of prior art comprises that a close-graded surface course 26 constitutes.On the layer 28 on its topped dense-graded aggregate base 30.The stratification structural section covers on the roadbed 30.
The feature and the fundamental characteristics thereof of the present invention and the employed material of prevailing roadway are discussed below.As mentioned above, structural meterials comprises close-graded and open type grating bituminous concrete and close-graded and open type graded aggregate base.
The material level becomes:
Bituminous concrete is made up of when the high temperature (loose grating) combined aggregate and the tarmac cement of good (level of confidentiality) or difference basically.Under certain condition, loose grating bituminous concrete.Can make with mulseal-but through the part high temperature of being everlasting, promptly be higher than environment temperature but be lower than liquid asphalt cement and use needed normal temperature.Pine grating bituminous concrete is a kind of novel material, comes out less than 20 years, and in 10 years, people are used as the high-quality pavement to loose grating pitch in the past, because it has the height slip resistance, is mainly used in the road surface.To join asphalt mixed soil different with the loose utmost point, the intensive bituminous concrete of joining must be processed into through tarmac cement, with assurance control density and void content, and this can not utilize the process for cold mixing (as emulsus or liquid bitumen) that causes construction back fluid loss to reach.The characteristic of bituminous concrete is subjected to the influence of bitumen content.Bitumen content has played the effect in hole in the control dense-graded asphalt concrete, generally seeks the value between 4%～6%, but actual value is generally between 5%～10%, below tabulation tarmac is described typically.
Tarmac
Summary: tarmac should be a steam refining pitch, is to produce from the mixture of crude asphalt oil product or refining liquid bitumen and refining natural asphalt, and it should be uniformly, not moisture and coal, coal tar, or the remnant of paraffin distillation.
Test requirements document:
Also should meet following table by viscosity grating regulation pitch requires:
This table and following all other tables are selected from associative cooperation committee and Southern California's associating underwriter's " explanation of public works building standard " of U.S. public works association Southern California's chapters and sections distance.
The aggregate of the concrete stone part of pine grating and close-graded is different with the particle of justifying, and is that the particle by wedge angle constitutes, and stipulates for the plane of disruption minimum value in the per unit building stones usually.With regard to dense-graded asphalt concrete, can contain mineral-filled material.This inserts is thinner than No. 200 sieves, and the maximum value that generally accounts for total amount is 3%～5%.The aggregate of bituminous concrete should be obeyed the durability technical requirements, should obey pellet hardness and mineralogy technical specification at least.These features can from design pulverize aggregate or produce machinery that cement brick breaks and chemical test obtain judging.The typical technology of used aggregate requires as follows:
Material
Pitch: the pitch that mixes with aggregate is tarmac
Aggregate: crushed aggregate is stone and is fit to following requirement
The requirement of test test method numbering
Wearing and tearing percentage ASTM C131
100 change 15Max
500 change 52Max
The fines of bituminous concrete is a sand, stone flour not, disintegrating slag, the admixture of mineral-filled thing or these materials.
If used No. 200 concrete finess of material medium pitch in the sieve inadequate, add mineral filler to be fit to formate gradation composition.
Mineral-filled material: mineral-filled material is made up of the fine powder material that crushed stone produces by portland cement or by mechanism, presses ASTM D422 test, and the rubble that Mechanical Method produces will meet the following table grating:
The granularity percentage
Cross sieve 75-100 No. 200
Less than 0.05mm 65-100
Less than 0.02mm 35-65
Less than 0.01mm 26-35
Less than 0.005mm 10-22
Synthetic aggregate
General provisions: in all process steps except that adding pitch and mineral-filled thing, when synthetic aggregate sample is tested for No. 217 by test method California, should have minimum 50 equivalent sand.
Form and grating: the grating and the pitch percentage of synthetic aggregate will meet the requirement of pointing out in the following table, and percentage shown in the table is all in the weight of dried aggregate.
Pass through percentage
Classification A B C D E
Ultra-fine and
Carefully limit in thick during sieve is thick
The minimum minimax minimax of size (mm) minimax minimax maximum
1-1/2（38.1） 100
1 （25.4） 90 100 100
3/4 （19.0） 78 90 95 100
1/2 （12.7） 64 78 74 88 95 100 100
3/8 （9.5） 54 68 62 76 72 88 95 100 100 100
No. 4 34 48 38 62 46 60 58 72 65 85
No. 8 25 35 28 40 28 42 34 48 45 65
No. 30 12 22 14 24 15 27 18 32 22 38
No. 50 8 16 10 18 10 20 13 23 16 28
No. 200 363747596 12
Bituminous cement % 4.5 5.5 4.6 5.8 4.8 6.0 4.8 6.5 6.0 8.0
Note: when using cinder aggregate, the percentage of bituminous cement can surpass above-mentioned value 2.0.
The bituminous cement amount of the accurate ratio of aggregate and every type of mixture should allotment under the engineer instructs.
The technical requirements (as wearing and tearing percentage and hardness) of close-graded and loose grating bituminous concrete design particle is identical.The loose grating asphalt concrete mixture that contains 3% AR, 4000 tarmacs is listed as follows
Screen size passes through percentage
(sieve)
1.0 inch 100
＃10 0-12
＃200 0-2
Aggregate also can be close-graded or loose grating, the quality material stone partly has edges and corners particle characteristics, with regard to the plane of disruption and durability with identical to the technical requirements of employed aggregate in the bituminous concrete, although this is not unique, the aggregate technical requirements example table that typically is used in dense-graded aggregate and the loose graded aggregate is as follows:
General provisions: crushed aggregate will be made up of crushed stone and stone flour fully.
Grade: aggregate should evenly and meet following grating:
Screen size (mm) percent passing
1-1/2″（38.1） 100
3/4″（19.0） 90-100
3/8″（9.5） 50-80
No. 4 35-55
No. 30 10-30
No. 200 2-9
The ASTMC131 grating
Quality requirement: material will meet following requirement:
The requirement of test test method numbering
The R-value
1California 301 minimums 80
Sand equivalent California 217 minimums 50
Wearing and tearing percentage ASTMC131
100 change maximum 15
500 change maximum 52
2.58 inches of proportion ASTMC127
2
(hair body saturated surface drying)
If 1 material has 55SE or more for a long time, the requirement of R-value will not considered.
2, not being higher than 15% by weight should be that mao body proportion is lower than 2.5 particle.
By test method California 229, if this material has little 40 durability, can not consider the to wear and tear requirement of percentage and proportion of engineer's tool.
The rubble product:
General provisions: following explanation has proposed the requirement to crushed stone and gravel.
Should be clean on all stone product qualities, hard firm, durable evenly without any being harmful to quality, hardness is low, and be loose, frangible, thin, long grain or stratified pieces, comminution of material, organic substance, oil-containing contains alkali or other hazardous substances.Unless otherwise indicated, all percentage people calculate by weight.
Crushed stone and stone flour: crushed stone is chippy stone or gravel product.By sieving greater than 3/8 inch that a part of material (9.5mm), at least contain 50% particle with three or more planes of disruption, what do not produce above-mentioned requirements section pellet in pulverizing should not surpass 5%, in the part of sieving by 3/8 inch (9.5mm) but not passing through to sieve for No. 4, below 10% the gravel particle.Crushed stone is by the nominal size design and should meet following grating:
Percent passing
1-1/2″ 100 - -
1″ 90-100 100 -
3/4″ 30-60 90-100 100
1/2″ 0-20 30-60 90-100
3/8″ - 0-20 20-60
No. 4 0-5 0-5 0-15
No. 8--0-5
Test grating A B B
Gravel should be formed by having the particle that is no more than a plane of disruption fully.
Construction technology
Standard implementation often is to determine with suitable public charg`e d'affaires's rule, divides cloth cover to exist with regard to structural section.Usually, grading is to the collimation that requires (level is with vertical) and the degree of depth, then before construction the compacting of low-density roadbed part.Six inches of the topmosts of Urban Council's compact technique requirement (being listed in public's engineering construction table) regulation support base or base, according to ASTM test determination D1557-70, being compacted to maximal density respectively is 90% and 95%.
The construction of prior art structural section is on aggregate base or the bituminous concrete direct filling roadbed after smooth.A kind of naturally occurring ratio is called the material of the surface soil high-quality of base, filling before base or the bituminous concrete, fills out and is placed on roadbed.In this case, the technical requirements of this layer of compacting with those to roadbed require identical.
Dense-graded aggregate generally is compacted and is 95% of experiment maximal density.But loose graded aggregate compact technique requires generally stipulate, because except mainly as under the outer condition of draining down, this layer seldom as using in the structural meterials.When using, SC, guaranteeing from the adjacent physical layering that connects the material, use native soil rather than make make good use of join grade gravel the time, also use the paveio(u)r eliminator once in a while.
Intensive compacting of joining bituminous concrete is to stipulate according to experiment or theoretical maximal density.When stipulating by the former, as mentioned above, general compacting requirement is 95%; When using the latter, compacting criteria commonly used is 92%.
In existing operation, the shelve temperature and type and quantity of the compactor of asphalt concrete layer are standardized equally.It generally is identical with dense-graded asphalt concrete that pine grating asphalt concrete technique requires.But the minimum compacted density of loose grating bituminous concrete is not stipulated usually.Yet when compacting, under awfully hot situation, the superiors' bituminous concrete can be filled (being that every square metre of sign indicating number sand covers between the 5-10 pound) and pave the way grating pitch (content commonly used is at 0.15～0.25 gallon every square yard) injection so that fine and close surface to be provided with emulsification or heat.
When loose grating bituminous concrete surface is when the friction and the basic role of anti-cunning are provided, the technology in the back generally has omission.
Mechanical property
Fig. 4 is the structural model on lamination commonly used road surface as shown in Figure 3.Parameter-definition shown in Fig. 4 is as follows:
e
1The critical response that draws of=dense-graded asphalt concrete
e
0=roadbed critical pressure strain
h
1The thickness of=layer 1
E
1The young's modulus of elasticity of=layer 1
U
1The poisson's ratio of=layer 1
To using the road surface meter to understand the validity of Computer Analysis of the structural model of Fig. 4, provide load, dwell time and the ambient conditions of approximate reflection material characteristics parameter.Be shown in and 5(a) and 5(b) in the stress distribution of this series of strata very typical, this figure is that prior art stratification construction cross section (Fig. 3 illustrates) stress that computer is made cuts the lotus characteristic curve to typical highway.As shown in the figure, (vertical stress under Fig. 5 (a) and two wheel loads is decay rapidly (increasing with the degree of depth) in dense-graded asphalt concrete layer 26 at a wheel, but its rate of decay reduces the upper face that another one high radial stressor layers is present in layer 26 significantly in the dense-graded aggregate basic unit 28 under layer 26, near axis, turn to, become high stretching strain in the asphalt concrete layer bottom.On layer 26 times, aggregate base 28 bears only very low compressive stress, and this stress reduces with the degree of depth.
When surface course 26 became broken and modification, the road surface was just destroyed.When enough repeated loads, loose grating bituminous concrete along with producing the crack and upwards open up fatigue failure by this layer biography, the bottom at roadbed has just been produced.Produce the accumulation plastic deformation when enough repeated loads make subgrade soil, produced the rut be full of cracks.
Show that in test room and work place study the weak point of repetition continues under the tensile stress load, dense-graded asphalt concrete produces fatigue fracture.Load repeat number and the stretching strain universal relation between loose grating asphalt concrete layer shows in Fig. 6.Destroy the logarithmic relationship between the number of iterations that generally is expressed as repetition maximum strain and material breaks.
Under the deformation that continuous temperature causes, the viscosity of pitch allows bituminous concrete lax under load, with prevent under the moderate temperature and/or the rapid situation of variations in temperature under caused temperature break.The characteristics of filler and quantity are stacked hybrid variables such as density and hole content and are all influenced fatigue strength and rigidity.Among Fig. 6, curve " A " is according to temperature (higher) load speed (lower), asphalt viscosity (less), and the characteristic of grating (pine level), air pocket content (increase) and bitumen content (reducing) is different from curve " B ".Resemble the variable of temperature and dwell time one class, when destruction is when becoming expression with fatigue stress rather than fatigue stress, may tangible adverse effect be arranged to fatigue strength.For example: increase temperature or reduce the dwell time.May make material before breaking, produce bigger strain level, but increase fragility, produce low breaking strain.Other variable effect is not too obvious.As increase and increased fatigue life the bitumen content and make the material deliquescing.Increase bitumen content on the other hand and generally increased compacted density, produced thick mixture, low air pocket content and must prolong fatigue life.
The young's modulus of elasticity of dense-graded asphalt concrete as shown in Figure 1 is the increasing function of carrying time, is the subtraction function of temperature.Dense-graded asphalt concrete poisson's ratio commonly used is between 0.4～0.5.
The transmissibility of dense-graded asphalt concrete is very responsive to bitumen content.General air pocket content is between 0.1～1.0 inch/every day greater than 5～6% mixture accepted value.When air pocket content less than 2～3% the time, the thermal characteristics that the low value of 0.0001 inch/every day can reach dense-graded asphalt concrete comprises and is similar to per hour every foot degree of depth 0.8BTU conductibility and be similar to the specific heat of every pound of 0.15BTU of every degrees Fahrenheit of every degrees Fahrenheit.
Pine grating bituminous concrete is when it has smaller tensile strength, is not feature with tension fatigue failure standard usually, and the general failure stress order of magnitude of loose grating bituminous concrete is lower than equality of temperature with the dense-graded asphalt concrete under the load-up condition.
Loose the opening when applicant finds that loose grating bituminous concrete has low rigidity and use (stress is lower than 10 pounds per square inch) under low load under tension force.However, when bearing pressure, its young's modulus of elasticity is identical even surpass dense-graded asphalt concrete, generates desirable road surface like this.Therefore, the rigidity of loose grating bituminous concrete is observed following relation along with boundary significantly increases:
E＝KQ
n
Wherein E is the Young mould, and Q is the initial stress invariant, and K and n are load time and temperature effect coefficient.The K value and the n value of general communications and transportation load and temperature condition, when young's modulus of elasticity initial stress invariant was every square feet of pound unit, its value was 100000 and 0.3～0.5.General high air pocket content above 20% makes water freely by loose grating bituminous concrete.Typical transmissibility is above 1000 feet/day.Its thermal property is identical with dense-graded asphalt concrete.
The rigidity of aggregate is responsive to its ambient stress equally.The exponential function relation of describing loose grating bituminous concrete also can be in order to represent typical aggregate rigidity.When young's modulus of elasticity and initial stress invariant during with pound/square inch expression, generally speaking, the K value of the aggregate base of dense-graded aggregate and n value are between 2000～3000 and between 0.4～0.7.Pine graded aggregate modulus a little higher than close-graded under same ambient stress.
The poisson's ratio of dense-graded aggregate also is the function of stress as shown in Figure 8.The dependence of poisson's ratio counter stress coexists identical in the loose graded aggregate, but probably to damp condition and insensitive.The dense-graded aggregate transmissibility is generally between 0.1～10 foot of every day.Pine graded aggregate transmissibility generally surpasses 1000 feet of every days.The aggregate thermal conductivity alters a great deal, and has reflected the variation of water content and Unit Weight.For the full dense-graded aggregate that closes, surpass every degrees Fahrenheit per hour every foot dark 25BTU value be reasonable.The thermal conductivity that is similar to glass and water under the individual cases is near every degrees Fahrenheit 0.5～300BTU of every foot degree of depth per hour.In loose graded aggregate, thermal conductivity is near bituminous concrete, less than the every degrees Fahrenheit of 1.0BTU per hour every foot dark.When indivedual unit values of water and mineral matter are 1.0 and per hour every foot when dark of the every degrees Fahrenheit of 0.17BTU, the specific heat of aggregate has also reflected moisture content.
The rigidity of natural soil depends on the characteristic of foundation soil to the sensitiveness of moisture content and stress state, and in general, young's modulus of elasticity reduces with the inverse function of stress difference.
The clay earth that plasticity is stronger is the most responsive to moisture content, and general young's modulus of elasticity is per square inch between 2000～10000 pounds, and the plastic clay of high moisture content takes off limit and the sand capping.The destruction of general ground is represented with the semilog relation with vertical strain as shown in Figure 9 and number of iterations.Criterion of failure is formulated from the pavement rutting depth used and traffic load are measured, generally 0.5 inch of the pavement destruction rut degree of depth or the taller and bigger place class of classifying.
Road surface characteristic
The applicant is the above-mentioned mechanical property in Shen, Shen and other improvement stratification flexible pavement that has obtained of showing in Fig. 1, in design road surface of the present invention, the applicant manages to obtain a kind of structural meterials and arranges, and integrates: obtain the highest pavement strength and endurance destruction under the expending of minimum; Minimum to the base transmissibility; Draining from the side of the surface seepage water on road surface is provided effectively; The thermal insulation of tensile structure key element till the present is provided, and does not utilize the prior art road surface; Improve the thermal insulation of roadbed thereby reduced the harmful thermal fracture of potential stretching resistance structural element and the bursting by freezing of roadbed; Level and smooth wear resistant road surface and other favourable advantage are provided.
In a word, the applicant has been found that it is feature that stratification of the present invention road surface has following mechanism: 20 fracture by fatigue strain (or stress) of dense-graded asphalt concrete layer and young's modulus of elasticity (rigidity is measured) be asphalt mixture, carrying temperature and the function when continuing carrying; The young's modulus of elasticity of pine grating asphalt concrete layer 14 depends on stress and environment temperature when carrying and lasting carrying; The young's modulus of elasticity of aggregate layer 16 and poisson's ratio are the functions of stress; Subgrade soil 12 is functions of stress state and moisture content.In addition, the young's modulus of elasticity of dense-graded aggregate basic unit 16 is functions of moisture content.Like this, draining when not allowing to carry when saturated, perhaps young's modulus of elasticity is subjected to very big influence.In addition, constitute the temperature of layer by cross section 10, leading moist and diffusivity has influenced the response of road surface to natural environment.These characteristics on road surface of the present invention have reflected the combination of modern unredeemed structural section and subgrade structure layer mechanical property.
Make comparisons with the prior art road surface, economy of the present invention is conspicuous, and the relative costs of dense-graded asphalt concrete layer and loose grating bituminous concrete, dense-graded aggregate base and loose graded aggregate base exist approximate ratio 20: 15: 5: 4.The use of low price material is than only using the full degree of depth of the prior art road surface of the most expensive material that tangible benefit is provided.Shown in the back, the layer according to the present invention distributes because the radiation propagation effect of power has produced compressive stress on top, road surface, produces tensile stress at its lower curtate, and this just makes the dense-graded asphalt concrete layer mainly be subjected to tensile stress.It will be appreciated that covering layer is asphalt concrete layer and pressure isolation.This isolation layer uses the higher material thin-layer of price and does not use in the full degree of depth of prior art or stratification road surface, and these materials are applied to the bending of crack progress on the bituminous concrete.Covering layer has been brought into play sufficient rigidity under pressure thus, makes the combination of layer body play the structure of the radiation propagation of independent body force.
Below the diagram comparison of accompanying drawing mechanism that road surface of the present invention is provided and the terms of mechanics of prior art stratification flexible pavement.Figure 10 (a) and 10(b) be according to the present invention (promptly as shown in the figure) one take turns or two wheel loads under the stress diagram of computing mechanism.These figure have reflected load and prior art stratification road surface with having played the radiation propagation of single structure power with prior art stratification road surface edition with parallel text invention total section, this at Figure 10 (a) with 10(b) by radial stress components oppositely can find out gradually in most layers of the entire profile from the compressive stress to the tensile stress.In the full degree of depth of prior art and stratification road surface, unique tensile stress layer that bears is positioned at profile top.Its result, only this one deck demonstrates the radiation propagation effect (top pressurized and bottom tension) of power.Remaining layer is of poor quality, and adhesive power is little, and tensile strength is little, does not participate in the response of the radiation propagation of power.Yet have only bottom and/or roadbed to bear vertical radial pressure.
In the present invention, as the radiation propagation active layer of Figure 10 (a) and the power that 10(b) illustrates with for bearing course 14,16,18 combinations, in high-quality dense-graded asphalt concrete layer 20, produce simple tension basically.So a layer 20 that play a part of layer 14,16 and 18 machinery completely cuts off with compressive stress.Bear layer 20 by the tensile stress that remains under the simple tension.Under repeated load, almost avoid occurring in the prior art pulling force and born buckling phenomenon in the layer.The minimizing of this bending is the key character that the present invention designs.Breaking of road surface is that tensile stress causes.Break or the destruction on the expansion in crack and consequent whole road surface because this bending becomes very easy.Although the crack occurs in the lower surface of layer 20, it upwards passes through the expansion of total section thereafter, owing to being prevented than slow of prior art pavement destruction more.
Moreover rupture process itself is postponed owing to improving bitumen content, and the density of the layer 20 of part by improving the above-mentioned auxiliary asphalt concrete mixture of mentioning has been improved the fatigue durability of bituminous concrete basically.Improve bitumen content and the bending that reduces the tensile stress bearing bed structure design combine the pavement construction of being convenient to have very thin asphalt concrete layer, so reduced the cost on whole road surface.At last, by the dense-graded asphalt concrete layer 20 that has improved bitumen content being placed on the bottom of structural section, the film sample water barrier that resembles that produces has limited seepage flow to roadbed, on the other hand on bituminous concrete top less close-graded layer make have an advantage become possibility from the structural section lateral drainage, kept the compressive stress supporting capacity of rigidity and whole design.The aggregate that sluices has improved heat resistance widely.
Figure 11,12 and 13 is figure of a cover computing mechanism, has compared according to the present invention and some mechanical foundation on as shown in Figure 3 stratification prior art road surface commonly used and expending.Modulus according to what-if close-graded road surface and improvement dense-graded asphalt concrete is 300000 a pounds/inch
2, subgrade modulus is 5000 a pounds/inch
2
The curve of Figure 11 has been represented when the maximum or contrast stretching strain as asphalt concrete layer bottom under the function of bed thickness of vehicle loading and ambient conditions.Curve A is the relation property of improvement dense-graded asphalt concrete layer 20 of the present invention.Curve, and curve B is the characteristic curve of Fig. 3 dense-graded asphalt concrete layer 26.Find out that obviously asphalt concrete layer stretching strain of the present invention is significantly smaller than given thick layer stretching strain in the prior art.On the contrary, the asphalt concrete layer of the known stretching strain order of magnitude is than thin on prior art stratification road surface in flexible pavement of the present invention, and it points out that strain is the subtraction function of bed thickness.
Can obviously find out from Figure 12 and 13, comprise that the pavement design of thin asphalt concrete layer has tangible cost advantage.Curve has been represented the critical tensile stress in the pavement asphalt concrete layer and the unit price of every square feet of dollar of relation between the compressive strain and whole road surface.
Curve A refers to road surface of the present invention, and curve B refers to prior art stratification road surface.Obviously, the thin asphalt concrete layer road surface of the present invention has produced than prior art and has had higher economic benefit.
Therefore, a kind of as can be seen structure technology of the improvement road surface that is made of novel stratification structural section is come out.By utilizing this technology, people can assist and build a kind of road surface, this material according to maintenance, endurance, continue traffic quality, aspects such as salvage value and operating expenses are than superior many in prior art high-quality asphalt road surface.
The present invention announcing in the most preferred embodiment now, but it never means and limited to by this, and its scope is only limited by the definition in the claim of back.
Claims (10)
1, a kind of asphalt pavement structure cross section of assisting on roadbed, integrate it is characterized in that it be by
A. various material layers, described layer distributes by selected order, from described roadbed to upper surface;
B. the layer that has maximum tension stress intensity is distributed near described roadbed.
2, according to claim 1 described flexible pavement, its feature of structural section is that further remaining layer has preliminary election compressive stress ability to bear.
3, according to claim 2 described asphalt pavement structure cross sections, its feature further is to have minimum transmissibility near described base course in described all layers.
4, according to claim 3 described flexible pavements, structural section is a dense-graded asphalt concrete near described base course wherein.
5, according to claim 4 described asphalt pavement structure cross sections, it is characterized in that further comprising one deck aggregate base at least.
6, according to claim 5 described asphalt pavement structure cross sections, it is characterized in that further comprising loose grating and dense-graded aggregate basic unit.
7, according to claim 6 described asphalt pavement structure cross sections, its feature further is the close bitumen layer layer of concrete of described loose graded aggregate basic unit.
8, the method in a kind of asphalt pavement structure of design cross section is characterized in that comprising the multiple material step that distributes, so that only bear compressive stress or tensile stress basically in the carrying in described each layer.
9,, it is characterized in that further comprising the described multiple layer step that distributes, so that bear tensile stress basically at whole bottom according to claim 8 described methods.
10, according to claim 9 described methods, the described layer that wherein distributes is so that bear tensile stress specially at described bottom.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 85105302 CN1007168B (en) | 1985-07-10 | 1985-07-10 | Improved asphalt road pauement |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 85105302 CN1007168B (en) | 1985-07-10 | 1985-07-10 | Improved asphalt road pauement |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN85105302A true CN85105302A (en) | 1987-01-14 |
| CN1007168B CN1007168B (en) | 1990-03-14 |
Family
ID=4794392
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 85105302 Expired CN1007168B (en) | 1985-07-10 | 1985-07-10 | Improved asphalt road pauement |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN1007168B (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2011079468A1 (en) * | 2009-12-31 | 2011-07-07 | 中交第一公路勘察设计研究院有限公司 | Method for protecting roadbeds in frozen soil area and pavement structure |
| CN109750574A (en) * | 2019-03-12 | 2019-05-14 | 中铁北京工程局集团有限公司 | A kind of base material bilayer company paving construction technology |
| CN111625911A (en) * | 2020-06-04 | 2020-09-04 | 中国科学院长春光学精密机械与物理研究所 | Modeling method for simulating screw connection |
-
1985
- 1985-07-10 CN CN 85105302 patent/CN1007168B/en not_active Expired
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2011079468A1 (en) * | 2009-12-31 | 2011-07-07 | 中交第一公路勘察设计研究院有限公司 | Method for protecting roadbeds in frozen soil area and pavement structure |
| CN109750574A (en) * | 2019-03-12 | 2019-05-14 | 中铁北京工程局集团有限公司 | A kind of base material bilayer company paving construction technology |
| CN111625911A (en) * | 2020-06-04 | 2020-09-04 | 中国科学院长春光学精密机械与物理研究所 | Modeling method for simulating screw connection |
| CN111625911B (en) * | 2020-06-04 | 2023-03-31 | 中国科学院长春光学精密机械与物理研究所 | Modeling method for simulating screw connection |
Also Published As
| Publication number | Publication date |
|---|---|
| CN1007168B (en) | 1990-03-14 |
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