CN111455768A - Flexible roadbed asphalt concrete structure and construction method thereof - Google Patents
Flexible roadbed asphalt concrete structure and construction method thereof Download PDFInfo
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- CN111455768A CN111455768A CN202010362229.5A CN202010362229A CN111455768A CN 111455768 A CN111455768 A CN 111455768A CN 202010362229 A CN202010362229 A CN 202010362229A CN 111455768 A CN111455768 A CN 111455768A
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- E—FIXED CONSTRUCTIONS
- E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
- E01C—CONSTRUCTION OF, OR SURFACES FOR, ROADS, SPORTS GROUNDS, OR THE LIKE; MACHINES OR AUXILIARY TOOLS FOR CONSTRUCTION OR REPAIR
- E01C7/00—Coherent pavings made in situ
- E01C7/08—Coherent pavings made in situ made of road-metal and binders
- E01C7/32—Coherent pavings made in situ made of road-metal and binders of courses of different kind made in situ
- E01C7/325—Joining different layers, e.g. by adhesive layers; Intermediate layers, e.g. for the escape of water vapour, for spreading stresses
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- E—FIXED CONSTRUCTIONS
- E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
- E01C—CONSTRUCTION OF, OR SURFACES FOR, ROADS, SPORTS GROUNDS, OR THE LIKE; MACHINES OR AUXILIARY TOOLS FOR CONSTRUCTION OR REPAIR
- E01C7/00—Coherent pavings made in situ
- E01C7/08—Coherent pavings made in situ made of road-metal and binders
- E01C7/18—Coherent pavings made in situ made of road-metal and binders of road-metal and bituminous binders
- E01C7/185—Isolating, separating or connecting intermediate layers, e.g. adhesive layers; Transmission of shearing force in horizontal intermediate planes, e.g. by protrusions
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- E—FIXED CONSTRUCTIONS
- E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
- E01C—CONSTRUCTION OF, OR SURFACES FOR, ROADS, SPORTS GROUNDS, OR THE LIKE; MACHINES OR AUXILIARY TOOLS FOR CONSTRUCTION OR REPAIR
- E01C7/00—Coherent pavings made in situ
- E01C7/08—Coherent pavings made in situ made of road-metal and binders
- E01C7/18—Coherent pavings made in situ made of road-metal and binders of road-metal and bituminous binders
- E01C7/24—Binder incorporated as an emulsion or solution
Abstract
A flexible roadbed asphalt concrete structure comprises a subbase layer, a base layer, an anti-fatigue asphalt layer, a tension-compression transition layer, an asphalt middle-lower surface layer and an asphalt upper surface layer; the subbase layer is arranged at the bottommost layer of the roadbed asphalt concrete structure; the base layer is arranged on the upper layer of the subbase layer; the anti-fatigue asphalt layer is arranged on the upper layer of the base layer; the tension-compression transition layer is arranged on the upper layer of the fatigue asphalt mixing layer; the middle and lower asphalt layers are arranged on the upper layer of the tension-compression transition layer; the upper asphalt layer is arranged on the upper layer of the middle and lower asphalt layers. The invention determines the structural scheme of the waterproof anti-rutting asphalt upper surface layer, the asphalt middle and lower surface layers, the tension-compression transition layer and the anti-fatigue asphalt layer, and designs and demonstrates three structural form parameters of the structural scheme, thereby providing the flexible base asphalt pavement with excellent performance.
Description
Technical Field
The invention relates to the field of pavement construction, in particular to a flexible roadbed asphalt concrete structure and a construction method thereof.
Background
The harbor district road uses the cement road surface in order to satisfy the heavy load demand more, and the abundant seam structure on cement road surface provides abundant route for moisture gets into the road surface structure inside, causes the weak and the coming to nothing of structural foundation from this. Once the cement pavement is weak in foundation and is empty, the service life of the cement pavement is rapidly reduced, and the cement pavement is very difficult to maintain after being damaged, which is characterized by large engineering quantity, long construction period and high cost.
Compared with a cement concrete pavement, the asphalt pavement has the advantages of continuity, no joint and high flatness; the method has a series of advantages of low noise, low dust emission and the like, and the reformation of the cement pavement into the asphalt pavement is a necessary development trend. However, the conventional asphalt pavement adopts a semi-rigid base asphalt pavement, and the design requirements of heavy-duty roads in harbor areas are difficult to meet due to a plurality of defects of the asphalt pavement. From the perspective of materials, the problem of high-temperature stability is always an important problem troubling asphalt pavements, and the traffic characteristics of heavy load, low speed, frequent steering and frequent acceleration and deceleration in port areas provide a rigorous requirement on the anti-rutting performance of asphalt pavements. From the structural point of view, the thickness of a pavement structure of a semi-rigid base asphalt pavement is about 60-80 cm (40-60 cm base layer + 18-20 cm asphalt surface layer), and the pavement structure is sensitive to heavy load and overload, so that if the long-term service life is ensured, the structure can be further thickened, the consumption of non-renewable resource crushed stone aggregates is very large, and especially under the conditions of environmental protection and strict restriction on the exploitation of the crushed stone aggregates in China at present, the sustainable development requirements of environmental protection and resource saving at present are difficult to meet; the traditional semi-rigid base asphalt pavement in China has the problems of heavy load and overload sensitivity and the defect of typical reflection cracks. The problem of heavy load and overload of the harbor district road can accelerate the damage of the semi-rigid base asphalt pavement, and the service life of the semi-rigid base asphalt pavement is obviously shortened. More importantly, the reflection cracks are inherent defects of the semi-rigid base layer, and the problem of the reflection cracks inevitably occurs to the pavement structure after the pavement structure is paved for 1-2 years, so that an effective way is provided for water to enter the pavement structure, and the damage of the pavement structure is further accelerated. From the perspective of mechanical properties, the mechanical properties of the semi-rigid base layer are easily affected by factors such as environment, construction, heavy load and the like, and the service life and the service state of the semi-rigid base layer are difficult to accurately estimate and judge due to the continuous change of the strength of the semi-rigid base layer and the complexity of internal damage development, which is also a core reason that the design precision of the current semi-rigid base layer asphalt pavement is insufficient and the decision of later maintenance is difficult. From the operation maintenance angle, semi-rigid base course is the main bearer layer of bituminous paving, and the emergence of its disease can produce fatal influence to the life of whole pavement structure, because semi-rigid base course's disguise makes to lack effectual assessment means to its performance state at present, also lacks effectual treatment means to its structural disease, leads to being difficult to carry out effectual maintenance to the pavement structure, in case take place to destroy the later stage maintenance difficulty, maintenance cycle length, and maintenance cost height.
The thickness of the pavement structure of the flexible base asphalt pavement is about 50-55 cm (15cm graded broken stone base and 35-40cm asphalt surface), the thickness of the asphalt pavement layer can be further reduced in a limited range according to the requirement of structural durability, and the total consumption of broken stone aggregates can be greatly reduced. The flexible base asphalt pavement has good water tightness and water stability, is low in sensitivity to heavy load and overload, more importantly, can effectively avoid the joint defect of a cement pavement and the reflection crack defect of the traditional semi-rigid base asphalt pavement, and can show more excellent service performance and long-term service durability through reasonable structure and material optimization design. The structure stress mechanism and damage evolution rule of the flexible base asphalt pavement are more definite, design precision and later maintenance decision precision are improved, the flexible base asphalt pavement is reasonably designed and maintained, and the service life of the flexible base asphalt pavement can reach more than 50 years. The main bearing layer of the flexible base asphalt pavement is on the asphalt surface layer, the judgment, evaluation and maintenance promotion of the performance state are concentrated in the range of the asphalt surface layer, the maintenance decision precision and maintenance efficiency are relatively higher, and the maintenance cost is lower. And maintenance in the long-term use process is mainly concentrated on the asphalt pavement, so that the maintenance is more convenient and faster, and the efficient cyclic recycling of the asphalt pavement material in the maintenance process is more favorably realized, thereby further realizing resource saving and economic saving. Therefore, compared with a semi-rigid base asphalt pavement, the flexible base asphalt pavement has more remarkable life cycle benefits and social environmental protection benefits.
Aiming at the concrete pavement of which the base course and the roadbed basically lose due structural strength, the reconstruction scheme adopted for reconstructing the pavement into the asphalt pavement mainly comprises two schemes: (1) crushing and excavating the original cement slabs so as to newly repair the asphalt pavement; (2) carrying out rubblization treatment on the original cement slabs, reserving a rubble layer as a roadbed or a pavement base, and paving the asphalt pavement on the basis. Considering the comprehensive consideration of the production amount of waste materials, environmental interference factors, construction period factors, construction efficiency, construction cost and the like, the second scheme is adopted for road surface modification, and a flexible asphalt road surface structure suitable for old cement concrete road surface modification needs to be designed.
Disclosure of Invention
In order to solve the existing problems, the invention discloses a flexible roadbed asphalt concrete structure, which has the following specific technical scheme: a flexible roadbed asphalt concrete structure comprises a subbase layer, a base layer, an anti-fatigue asphalt layer, a tension-compression transition layer, an asphalt middle-lower surface layer and an asphalt upper surface layer;
the subbase layer is arranged at the bottommost layer of the roadbed asphalt concrete structure, the original cement pavement slab is subjected to in-situ crushing through a rubblization process, and the crushed rubble layer is rolled on site to be used as the subbase layer of the pavement structure;
the base layer is arranged on the upper layer of the subbase layer and adopts graded broken stones; the structure layer is used for supporting the structure layer of the asphalt mixing layer and is used for bearing the flexible transition effect from asphalt to a cement board crushed layer, the hidden danger of reflection cracks existing in the later period when the crushed insufficient macadam surface particles of the subbase layer are larger is eliminated, and the uneven settlement existing on the surface after the subbase layer is crushed and compacted is filled;
the anti-fatigue asphalt layer is arranged on the upper layer of the base layer; the anti-fatigue asphalt layer is made of AC-13 asphalt concrete; the anti-fatigue asphalt layer laid on the upper layer of the base layer is a main bending and stretching deformation area in the roadbed structure and is used as a leveling layer of the base layer, and the anti-fatigue performance of the roadbed structure is improved and is used as an anti-fatigue layer of the asphalt pavement;
the tension-compression transition layer is arranged on the upper layer of the fatigue asphalt mixing layer; the tension-compression transition layer adopts one of ATB-25 asphalt macadam and AC-20 asphalt concrete and is used as a tension-compression transition area between the anti-fatigue asphalt layer and the upper asphalt layer, so that the direct action of load on the upper asphalt layer is reduced to generate higher pressure, and the tensile stress borne by the lower asphalt layer is reduced;
the asphalt middle and lower surface layer is arranged on the upper layer of the tension-compression transition layer; the middle and lower layers of the asphalt adopt one or two of AC-20 asphalt concrete and AC-25 asphalt concrete; the asphalt has excellent anti-rutting performance and excellent water-tight performance, and the main rutting development area of the pavement is controlled in the lower surface layer of the asphalt;
the asphalt upper surface layer is arranged on the upper layer of the asphalt middle and lower surface layers; the upper asphalt layer is made of AC-16 asphalt concrete; the road bed structure has good compactness, and can prevent rainwater and sprinkled water from entering the interior of the road bed structure.
Further, the design thickness of the underlayer is 20-30 cm.
Further, the design thickness of the base layer is 15 cm.
Further, the design thickness of the anti-fatigue asphalt layer is 6-8 cm.
Furthermore, the anti-fatigue asphalt layer adopts modified asphalt as a cementing material.
Further, the design thickness of the tension-compression transition layer is 10-12 cm.
Further, the designed thickness of the lower layer in the asphalt is 8-15 cm.
Furthermore, modified asphalt is adopted as a cementing material for the middle and lower layers of the asphalt.
The further upper layer of bitumen is designed to have a thickness of 4-5 cm.
Furthermore, the upper asphalt layer adopts high-modulus anti-rutting asphalt as a cementing material.
Furthermore, the anti-fatigue asphalt layer, the tension-compression transition layer, the asphalt middle and lower surface layer and the asphalt upper surface layer form an asphalt mixing layer.
Further, the lower middle asphalt layer and the upper asphalt layer form an anti-rutting layer.
According to the flexible roadbed asphalt concrete structure, the construction method of the flexible roadbed asphalt concrete structure is provided:
(1) crushing and compacting the original cement concrete pavement through rubblization modification of the cement pavement to form a subbase layer;
①, punching and presplitting a single cement concrete slab by adopting a hydraulic hammer;
② crushing the concrete slab by adopting multi-hammer crushing equipment;
(2) laying graded crushed stone on the base layer to form a base layer;
(3) paving AC-13 asphalt concrete on the base layer to form an anti-fatigue asphalt layer, wherein the AC-13 asphalt concrete is paved twice and has a two-layer structure;
(4) laying one of ATB-25 asphalt macadam and AC-20 asphalt concrete on the anti-fatigue asphalt layer to form a tension-compression transition layer;
(5) laying one or two of AC-20 asphalt concrete and AC-25 asphalt concrete on the tension-compression transition layer to form an asphalt middle lower surface layer;
(6) laying AC-16 asphalt concrete over the middle and lower asphalt layers to form an upper asphalt layer;
the construction method is further improved in that after the original cement concrete pavement is crushed and compacted, graded broken stones are laid to form a base layer, emulsified asphalt is spread on the top surface of the base layer to serve as a permeable layer, and 50% of slow-breaking emulsified asphalt is spread according to the dosage of 2.5-3.5 (kg/square meter).
Further, the construction method of the invention is improved in that AC-13 asphalt concrete is laid on the base layer to form the fatigue-resistant asphalt layer.
Furthermore, the construction method is improved in that one of quick-cracking or medium-cracking emulsified asphalt and modified emulsified asphalt is adopted as a bonding layer between the anti-fatigue asphalt layer and the tension-compression transition layer.
Furthermore, the construction method of the invention is improved in that one of quick-cracking or medium-cracking emulsified asphalt and modified emulsified asphalt is adopted as a sticky layer between the tension-compression transition layer and the middle and lower asphalt layers.
Furthermore, the construction method of the invention is improved in that one of modified asphalt or modified emulsified asphalt is adopted as a sticky layer between the lower surface layer and the upper surface layer of the asphalt, and the using amount is not less than 1L/square meter.
The invention has the beneficial effects that:
aiming at carrying out rubble transformation on a broken concrete pavement in a harbor area, the invention provides a combined rubble transformation scheme of hydraulic hammer drilling and presplitting and multi-hammer breaking on the original concrete pavement, thereby avoiding the process of excavating and transferring the original concrete structure, avoiding repeated construction on a base structure and reducing the construction period and the construction cost; and a good subbase structure is formed on the modified asphalt layer, and the subbase structure is stable.
Aiming at using factors such as large load capacity of a port area road surface, a common low-speed form of a road automobile and the like, the invention considers the mechanical property, key function and performance requirement, long-term performance decay rule and damage characteristic of an asphalt concrete surface layer, and predicts the road performance of a rubblized and modified flexible asphalt road surface structure based on an asphalt road surface performance prediction model established by a mechanical experience method, wherein the road performance comprises track depth development prediction and asphalt surface layer fatigue life prediction, determines a structural scheme of a waterproof anti-track asphalt upper surface layer, an asphalt middle and lower surface layer, a tension and compression transition layer and an anti-fatigue asphalt layer, designs and demonstrates three structural form parameters of the structural scheme, and provides the flexible base asphalt road surface with excellent performance.
Drawings
Fig. 1 is a sectional view of an asphalt concrete structure according to example 1 of the present invention.
Fig. 2 is a sectional view of a bituminous concrete structure according to example 2 of the present invention.
Fig. 3 is a sectional view of a bituminous concrete structure according to example 3 of the present invention.
FIG. 4 is a table showing the calculated parameters of the asphalt concrete structure according to example 1 of the present invention.
FIG. 5 is a graph of the shear stress of an asphalt mix at different loads in a highway asphalt design specification.
FIG. 6 is a bar graph of the standard load, actual axial load and tensile-compressive transition layer bottom tensile stress in examples 1-3 of the present invention.
FIG. 7 is a bar graph of the standard load, actual axial load and tensile-compressive transition layer bottom tensile strain in examples 1-3 of the present invention.
FIG. 8 is a graph of the tensile stress distribution of the bottom of the tension compression transition layer of example 1 of the present invention.
FIG. 9 shows the permanent set of the asphalt mixture layer in example 1 of the present invention.
FIG. 10 shows the permanent set of the asphalt mixture layer in example 2 of the present invention.
FIG. 11 shows the permanent set of the asphalt mixture layer in example 3 of the present invention.
FIG. 12 shows the fatigue life of examples 1 to 3 of the present invention.
List of reference numerals:
an underlayer 1;
a base layer 2;
an anti-fatigue asphalt layer 3;
the transition layer 4 is drawn and pressed;
an asphalt middle lower layer 5;
and an asphalt upper layer 6.
Detailed Description
In order to make the technical scheme of the invention clearer and clearer, the invention is further described with reference to the accompanying drawings, and any scheme obtained by carrying out equivalent replacement and conventional reasoning on the technical characteristics of the technical scheme of the invention falls into the protection scope of the invention.
Example 1
The flexible roadbed asphalt concrete structure can be seen by combining the attached drawings, wherein:
the subbase layer is crushed and compacted on the original cement concrete pavement, and the thickness of the subbase layer after rubblization is 25 cm;
spreading 50% slow-breaking emulsified asphalt on the top surface of the subbase layer, wherein the dosage is 3 kg/square meter;
paving graded broken stones on the subbase layer to form a base layer, wherein the base layer is paved with the graded broken stones, and the paving thickness is 15 cm;
spreading 50% slow-breaking emulsified asphalt on the top surface of the base layer, wherein the dosage is 2.5 kg/square meter;
laying an anti-fatigue asphalt layer on the base layer, wherein the anti-fatigue asphalt layer is formed by laying AC-13 asphalt concrete, the AC-13 asphalt concrete is laid twice, the laying thickness is 2 layers by 4cm, and the total thickness of the anti-fatigue asphalt layer is 8 cm;
spreading modified emulsified asphalt on the top surface of the fatigue-resistant asphalt layer to serve as a bonding layer;
laying a tension-compression transition layer on the anti-fatigue asphalt layer, wherein ATB-25 asphalt macadam is laid on the tension-compression transition layer, and the laying thickness is 10 cm;
spreading medium-cracked emulsified asphalt on the top surface of the tension-compression transition layer to serve as a bonding layer;
paving an asphalt middle and lower surface layer on the tension-compression transition layer, wherein the asphalt middle and lower surface layer is paved with AC-20 asphalt concrete with the paving thickness of 8 cm;
the top of the lower layer of asphalt is spread with modified emulsified asphalt as adhesive layer in the amount of 1.5L/sq m.
And (3) paving an asphalt upper surface layer on the middle and lower asphalt layers, wherein AC-16 asphalt concrete is paved on the asphalt upper surface layer, and the paving thickness is 5 cm.
Example 2
The flexible roadbed asphalt concrete structure can be seen by combining the attached drawings, wherein:
the subbase layer is crushed and compacted on the original cement concrete pavement, and the thickness of the subbase layer after rubblization is 25 cm;
spreading 50% slow-breaking emulsified asphalt on the top surface of the subbase layer, wherein the dosage is 3 kg/square meter;
paving graded broken stones on the subbase layer to form a base layer, wherein the base layer is paved with the graded broken stones, and the paving thickness is 15 cm;
spreading 50% slow-breaking emulsified asphalt on the top surface of the base layer, wherein the dosage is 2.5 kg/square meter;
laying an anti-fatigue asphalt layer on the base layer, wherein the anti-fatigue asphalt layer is formed by laying AC-13 asphalt concrete, the AC-13 asphalt concrete is laid twice, the laying thickness is 2 layers by 4cm, and the total thickness of the anti-fatigue asphalt layer is 8 cm;
spreading modified emulsified asphalt on the top surface of the fatigue-resistant asphalt layer to serve as a bonding layer;
laying a tension-compression transition layer on the anti-fatigue asphalt layer, wherein ATB-25 asphalt macadam is laid on the tension-compression transition layer, and the laying thickness is 12 cm; spreading medium-cracked emulsified asphalt on the top surface of the tension-compression transition layer to serve as a bonding layer;
paving an asphalt middle and lower surface layer on the tension-compression transition layer, wherein the asphalt middle and lower surface layer is paved with AC-20 asphalt concrete with the paving thickness of 10 cm;
the top of the lower layer of asphalt is spread with modified emulsified asphalt as adhesive layer in the amount of 1.5L/sq m.
And (3) paving an asphalt upper surface layer on the middle and lower asphalt layers, wherein AC-16 asphalt concrete is paved on the asphalt upper surface layer, and the paving thickness is 5 cm.
Example 3
The flexible roadbed asphalt concrete structure can be seen by combining the attached drawings, wherein:
the subbase layer is crushed and compacted on the original cement concrete pavement, and the thickness of the subbase layer after rubblization is 25 cm;
spreading 50% slow-breaking emulsified asphalt on the top surface of the subbase layer, wherein the dosage is 3 kg/square meter;
paving graded broken stones on the subbase layer to form a base layer, wherein the base layer is paved with the graded broken stones, and the paving thickness is 16 cm;
spreading 50% slow-breaking emulsified asphalt on the top surface of the base layer, wherein the dosage is 2.5 kg/square meter;
laying an anti-fatigue asphalt layer on the base layer, wherein the anti-fatigue asphalt layer is formed by laying AC-13 asphalt concrete, the AC-13 asphalt concrete is laid twice, the laying thickness is 2 layers by 4cm, and the total thickness of the anti-fatigue asphalt layer is 8 cm;
spreading modified emulsified asphalt on the top surface of the fatigue-resistant asphalt layer to serve as a bonding layer;
laying a tension-compression transition layer on the anti-fatigue asphalt layer, wherein ATB-25 asphalt macadam is laid on the tension-compression transition layer, and the laying thickness is 12 cm;
spreading medium-cracked emulsified asphalt on the top surface of the tension-compression transition layer to serve as a bonding layer;
paving an asphalt middle-lower surface layer on the tension-compression transition layer, wherein the asphalt middle-lower surface layer is of a two-side structure, and paving AC-25 asphalt concrete with the paving thickness of 8 cm; then paving AC-20 asphalt concrete with the paving thickness of 7 cm;
the top of the lower layer of asphalt is spread with modified emulsified asphalt as adhesive layer in the amount of 1.5L/sq m.
And (3) paving an asphalt upper surface layer on the middle and lower asphalt layers, wherein AC-16 asphalt concrete is paved on the asphalt upper surface layer, and the paving thickness is 5 cm.
(1) And (3) checking the stability of the roadbed asphalt concrete structure:
the shear stress distribution state of the asphalt pavement can reflect the rutting development state of the asphalt pavement to a certain degree. The shear stress calculation is carried out on the standard load (100kN axle weight and 700kPa tire pressure) and the actual axle load (250kN axle weight and 900kPa tire pressure) of the road surface structure designed on the asphalt road surface by utilizing finite element software ABAQUS, and the structure calculation parameters are shown in figure 4.
The distribution conditions of the shear stress of the asphalt mixing layer under the action of the standard load and the two overload loads in the highway design specification are calculated by using finite element software and are shown in figure 5.
According to the graph shown in the attached figure 5, the tensile-compression transition layer shear stress of ATB-25 asphalt macadam is only 0.15MPa, the area with larger shear stress is mainly distributed on the upper middle layer, and the anti-rutting layer formed by 5cm of AC-16 asphalt concrete and 8cm of AC-20 asphalt concrete can provide enough high-temperature stability; however, under the condition of heavy load on the road surface, the maximum value of the shear stress is far larger than that of the shear stress generated by the standard load, and the influence depth of the shear stress is far larger than that of the standard load. The shear stress at the position 6cm away from the top surface of the tension-compression transition layer on the road surface reaches the shear stress of the top surface of the tension-compression transition layer under the standard load, but the track resistance of the tension-compression transition layer is poor, and the 6cm away from the upper part of the tension-compression transition layer under the heavy load condition of the road surface generates larger permanent deformation.
Taking a shear stress critical value of a road surface rutting caused under the action of a standard load of a road as a standard, wherein the rutting occurs within 8cm from a road surface; comparing with the attached figure 5, when the vehicle is overloaded to 40 tons and 60 tons of the whole vehicle, the shear stress of the anti-rutting layer is attenuated to the critical value, the influence depth of the rutting is 17cm and 20cm, and the temperature drop of the anti-rutting layer is considered to be slightly reduced, and the influence depth of the rutting is reduced to 15-20 cm.
Namely, the pavement thickness of the anti-rutting layer is at least 15cm by considering the factors of heavy load and overload of the pavement, and the pavement thickness of the anti-rutting layer reaches 20cm for further considering the factors of rutting increase caused by the vehicle-mounted running speed of the pavement.
In the embodiment 1, the thickness of the anti-rutting layer formed by the middle lower layer of the asphalt and the upper layer of the asphalt is 13cm, so that the anti-rutting requirement of the road surface without overload can be completely met, and the anti-rutting requirements of the road surface with overload and vehicle-mounted low-speed running of the road surface cannot be met.
In the embodiment 2, the thickness of the anti-rutting layer formed by the middle and lower asphalt layers and the upper asphalt layer is 15cm, so that the anti-rutting requirements of heavy load and overload of the pavement can be completely met, and the anti-rutting requirements of vehicle-mounted low-speed running of the pavement cannot be met.
In the embodiment 3, the thickness of the anti-rutting layer formed by the middle lower layer of the asphalt and the upper layer of the asphalt is 20cm, so that the anti-rutting requirements of heavy load and overload of the road surface and vehicle-mounted low-speed running of the road surface can be completely met.
(2) Checking the fatigue resistance of the roadbed asphalt concrete structure:
the fatigue life of the asphalt mixing layer is generally controlled by using the tensile stress or tensile strain of the tension-compression transition layer. The pairs of the tensile stress and the tensile strain of the tensile-compression transition layer of the standard load (100kN axle weight, 700kPa tire pressure) and the actual axle load (250kN axle weight, 900kPa tire pressure) designed on the asphalt pavement by using the finite element software ABAQUS are respectively shown in the attached drawings 6 and 7;
under the action of 60 tons of overloaded vehicles, the tensile stress of the bottom of the tension-compression transition layer of the pavement structure in the embodiment 1 reaches more than 1.0MPa, which is far higher than the requirement of the tensile stress in normal highway design; in examples 2 and 3, compared with example 1, a thicker tensile-compression transition layer structure is used, and although the tensile stress of the tensile-compression transition layer bottom and the tensile force of the tensile-compression transition layer bottom are both reduced, the tensile stress and the tensile strain of the asphalt mixed layer bottom of examples 2 and 3 still have higher values for the load of overload to 60 tons.
Therefore, a design of a targeted anti-fatigue layer for the tension-compression transition layer bottom is needed. Taking the embodiment 1 with the maximum tensile stress value and the maximum tensile force value of the tensile and compressive transition layer bottom as an example, the tensile stress distribution of the tensile and compressive transition layer bottom of the embodiment 1 is shown in fig. 8;
as shown in the attached figure 8, within the range of 6cm of the bottom of the tension-compression transition layer of the embodiment 1, the tensile stress of the bottom of the tension-compression transition layer is more than 0.5MPa, when the tensile stress of the material reaches 0.5MPa, the tension-compression transition layer is broken due to fatigue, and therefore 8cm of AC-13 asphalt concrete is paved as the fatigue-resistant asphalt layer on the bottom surfaces of the tension-compression transition layers of the embodiments 1, 2 and 3.
(3) Checking the permanent deformation of the asphalt mixed layer with the roadbed asphalt concrete structure:
the layering is of the form: the surface layer is divided into one layer from 10mm to 20 mm; a second asphalt mixture layer, wherein the thickness of each layer is not more than 25 mm; a third asphalt mixture layer, wherein the thickness of each layer is not more than 100 mm; and the fourth layer and the asphalt mixture layer below the fourth layer are used as a layered layer. (quoted from the design Specification for road asphalt pavement)
Obtaining the rutting test permanent deformation of each layer of asphalt mixture according to the rutting test under the standard condition, and calculating the layered permanent deformation and the total permanent deformation of the asphalt surface layer:
in the formula: raThe total permanent deformation of the asphalt surface layer is mm;
Rai: i-th delamination set, mm;
n: the number of layers;
Tpefpermanent deformation equivalent temperature of the asphalt mixture layer, DEG C; t ispef＝Tξ+0.16ha，TξIs a reference equivalent temperature;
Ne3designing the accumulated action times of the axle load as equivalent;
hii-th delamination thickness, mm;
h0the thickness of the rut test piece is mm;
R0ipermanent deformation in rut test, mm;
kRi: the correction coefficient is calculated by the following equation:
d1＝-1.35×10-4ha 2+8.18×10-2ha-14.50
d2＝8.78×10-7ha 2-1.50×10-3ha+0.90
Zithe depth of the ith layer of the asphalt mixture layer is mm; the first layer is 15mm, and the rest layers are road surface depth from the center of the layer.
haThickness of bituminous mixture layer, mm.
piThe vertical compressive stress of the ith layering top surface of the bituminous mixture is MPa; calculated according to the theory of elastic layered system.
FIG. 9, FIG. 10 and FIG. 11 show the permanent set values of the asphalt mixture layers of examples 1, 2 and 3, respectively.
(4) Checking the fatigue cracking of the asphalt upper surface layer of the roadbed asphalt concrete structure:
the fatigue cracking life of the asphalt mixture layer is calculated according to the tensile strain of the asphalt mixture layer obtained by the structural analysis of the pavement and according to the following formula:
in the formula: nf1 is fatigue cracking life (number of axles) of the asphalt mixture layer;
β is a target reliability index;
adjusting coefficient for seasonal frozen soil area;
kb is fatigue loading mode coefficient, calculated as:
ea-dynamic compression modulus (MPa) of asphalt mixture at 20 ℃;
VFA ═ asphalt saturation (%) of asphalt mix;
ha ═ asphalt mix layer thickness (mm);
a, the bottom tensile strain of an asphalt mixture layer is 10-6; calculated from the elastic layer system.
The fatigue checking results of example 1, example 2 and example 3 are shown in fig. 12.
As shown in fig. 12, the fatigue life of the asphalt mixture layer for road surfaces of example 1 was already long, and the fatigue life of the asphalt mixture layers of examples 2 and 3 was further improved.
The invention has the beneficial effects that:
aiming at carrying out rubble transformation on a broken concrete pavement in a harbor area, the invention provides a combined rubble transformation scheme of hydraulic hammer drilling and presplitting and multi-hammer breaking on the original concrete pavement, thereby avoiding the process of excavating and transferring the original concrete structure, avoiding repeated construction on a base structure and reducing the construction period and the construction cost; and a good subbase structure is formed on the modified asphalt layer, and the subbase structure is stable.
Aiming at using factors such as large load capacity of a port area road surface, a common low-speed form of a road automobile and the like, the invention considers the mechanical property, key function and performance requirement, long-term performance decay rule and damage characteristic of an asphalt concrete surface layer, and predicts the road performance of a rubblized and modified flexible asphalt road surface structure based on an asphalt road surface performance prediction model established by a mechanical experience method, wherein the road performance comprises track depth development prediction and asphalt surface layer fatigue life prediction, determines a structural scheme of a waterproof anti-track asphalt upper surface layer, an asphalt middle and lower surface layer, a tension and compression transition layer and an anti-fatigue asphalt layer, designs and demonstrates three structural form parameters of the structural scheme, and provides the flexible base asphalt road surface with excellent performance.
Claims (10)
1. A flexible roadbed asphalt concrete structure is characterized by comprising a subbase layer, a base layer, an anti-fatigue asphalt layer, a tension-compression transition layer, an asphalt middle-lower surface layer and an asphalt upper surface layer;
the subbase layer is arranged at the bottommost layer of the roadbed asphalt concrete structure, the original cement pavement slab is subjected to in-situ crushing through a rubblization process, and the crushed rubble layer is rolled on site to be used as the subbase layer of the pavement structure;
the base layer is arranged on the upper layer of the subbase layer and adopts graded broken stones; the structure layer is used for supporting the structure layer of the asphalt mixing layer and is used for bearing the flexible transition effect from asphalt to a cement board crushed layer, the hidden danger of reflection cracks existing in the later period when the crushed insufficient macadam surface particles of the subbase layer are larger is eliminated, and the uneven settlement existing on the surface after the subbase layer is crushed and compacted is filled;
the anti-fatigue asphalt layer is arranged on the upper layer of the base layer; the anti-fatigue asphalt layer is made of AC-13 asphalt concrete; the anti-fatigue asphalt layer laid on the upper layer of the base layer is a main bending and stretching deformation area in the roadbed structure and is used as a leveling layer of the base layer, and the anti-fatigue performance of the roadbed structure is improved and is used as an anti-fatigue layer of the asphalt pavement;
the tension-compression transition layer is arranged on the upper layer of the fatigue asphalt mixing layer; the tension-compression transition layer adopts one of ATB-25 asphalt macadam and AC-20 asphalt concrete and is used as a tension-compression transition area between the anti-fatigue asphalt layer and the upper asphalt layer, so that the direct action of load on the upper asphalt layer is reduced to generate higher pressure, and the tensile stress borne by the lower asphalt layer is reduced;
the asphalt middle and lower surface layer is arranged on the upper layer of the tension-compression transition layer; the middle and lower layers of the asphalt adopt one or two of AC-20 asphalt concrete and AC-25 asphalt concrete; the asphalt has excellent anti-rutting performance and excellent water-tight performance, and the main rutting development area of the pavement is controlled in the lower surface layer of the asphalt;
the asphalt upper surface layer is arranged on the upper layer of the asphalt middle and lower surface layers; the upper asphalt layer is made of AC-16 asphalt concrete; the road bed structure has good compactness, and can prevent rainwater and sprinkled water from entering the interior of the road bed structure.
2. A flexible roadbed asphalt concrete structure as claimed in claim 1, wherein the design thickness of the fatigue resistant asphalt layer is 6-8 cm.
3. The flexible roadbed asphalt concrete structure of claim 1, wherein the design thickness of the tension-compression transition layer is 10-12 cm.
4. A flexible road-based asphalt concrete structure according to claim 1, characterized in that the designed thickness of the lower layer in the asphalt is 8-15 cm.
5. A flexible roadbed asphalt concrete structure as claimed in claim 1, wherein the middle and lower asphalt layers adopt modified asphalt as a cementing material.
6. A flexible road-based asphalt concrete structure according to claim 1, characterized in that said asphalt upper layer uses high modulus rutting resistant asphalt as a cementing agent.
7. The flexible roadbed asphalt concrete structure of claim 1, wherein a construction method of the flexible roadbed asphalt concrete structure is provided:
(1) crushing and compacting the original cement concrete pavement through rubblization modification of the cement pavement to form a subbase layer;
①, punching and presplitting a single cement concrete slab by adopting a hydraulic hammer;
② crushing the concrete slab by adopting multi-hammer crushing equipment;
(2) laying graded crushed stone on the base layer to form a base layer;
(3) paving AC-13 asphalt concrete on the base layer to form an anti-fatigue asphalt layer, wherein the AC-13 asphalt concrete is paved twice and has a two-layer structure;
(4) laying one of ATB-25 asphalt macadam and AC-20 asphalt concrete on the anti-fatigue asphalt layer to form a tension-compression transition layer;
(5) laying one or two of AC-20 asphalt concrete and AC-25 asphalt concrete on the tension-compression transition layer to form an asphalt middle lower surface layer;
(6) AC-16 asphalt concrete is laid over the middle and lower asphalt layers to form an upper asphalt layer.
8. The construction method of the flexible roadbed asphalt concrete structure according to claim 7, wherein when the original cement concrete pavement is crushed and compacted and graded broken stones are laid to form a base layer, emulsified asphalt is spread on the top surface of the base layer to serve as a permeable layer, and 50% of slow-breaking emulsified asphalt is spread according to the dosage of 2.5-3.5 (kg/square meter).
9. The construction method of the flexible roadbed asphalt concrete structure as claimed in claim 7, wherein one of cracked or middle-cracked emulsified asphalt and modified emulsified asphalt is adopted as the adhesive layer between the tension-compression transition layer and the asphalt middle lower layer.
10. The method of claim 7, wherein one of modified asphalt and modified emulsified asphalt is used as a bonding layer between the lower asphalt layer and the upper asphalt layer, and the amount of the bonding layer is not less than 1L/m.
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| CN113550190A (en) * | 2021-08-02 | 2021-10-26 | 云南云岭高速公路工程咨询有限公司 | Construction method of highway asphalt concrete |
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Application publication date: 20200728 |