Single-lane concrete pavement structure for preventing and treating center joint cracking and construction method

Abstract

The invention relates to the technical field of roadbed and pavement engineering, in particular to a single-lane concrete pavement structure for preventing and treating center joint cracking and a construction method. Comprising the following steps: 1, after the overall rolling construction of a base layer is finished, scarifying a base layer filler within a certain width and certain depth range of a road center line; 2, leveling is conducted, wherein redundant base layer materials are removed but not compacted; and 3, concrete surface layer construction is carried out. The concrete pavement slab is used for improving or avoiding the bending fracture damage caused by a three-point anti-bending stress mode that the middle part of a road is upwards supported and the two sides of the road are downwards formed by a traditional concrete pavement slab under the vehicle load. The underlying stress state of the concrete panel is improved, the bearing capacity of the concrete panel is improved to the maximum extent, technical construction is easy and convenient, the construction cost is low, and the effect is reliable.

Description

Technical Field

[0001] The invention relates to the technical field of roadbed and pavement engineering, and in particular to a single-lane concrete pavement structure for preventing and controlling center cracking and a construction method. Background Art

[0002] Cement concrete pavement is widely used in the process of road construction in my country, but a series of diseases of cement concrete pavement, such as cracks, broken boards, etc., seriously affect the service life of the pavement. This phenomenon not only wastes resources, but also affects the normal passage of traffic. Once the cement concrete pavement has broken boards, many advantages of the cement pavement will no longer exist, and the disadvantage of difficult maintenance will be very prominent. Due to the high stiffness of cement concrete, the fracture of the cement panel is a brittle fracture, which is sudden and difficult to repair once broken.

[0003] Previous research has focused on materials, cement concrete mix ratio, construction details control, etc. to prevent and treat such diseases. For example, the mix ratio of cement concrete must be strictly controlled, the joint cutting work must be carried out promptly and accurately after the cement concrete pavement construction is completed, and the quality of construction materials must be controlled. However, there is little research on improving the underlying conditions of cement concrete road panels.

[0004] There are many mechanisms and causes for cracks, broken boards and other defects in concrete pavement structures. Some broken boards are caused by the tensile stress generated by the initial shrinkage of concrete being hindered during construction, which exceeds the tensile strength of concrete; some are caused by the temperature warping stress generated by the large size of the board exceeding the bending tensile strength of concrete; there are also broken boards caused by excessive vehicle loads, stress concentration, etc., and there are also broken boards caused by damage to the filler, which leads to the bottom of the board being hollowed out, thus forming broken boards. Concrete pavement structure belongs to the category of elastic foundation plate theory. The lower part of the concrete road panel belongs to the elastic semi-space foundation, which has a great influence on the force of the concrete panel. The occurrence of the disease is closely related to the elastic semi-space foundation under the concrete panel.

[0005] Through extensive research, it was found that due to the narrow roadbed, road humps, roadbed creep, vehicle loads, etc., a large number of single-lane cement concrete slabs have a lot of defects concentrated in longitudinal cracks and broken slabs. Figure 1 As shown in the figure, under vehicle load, the concrete panel forms a three-point bending stress mode with the middle supporting upward and the two ends downward, which bends and breaks upward, resulting in cracks and broken panels in the center of the concrete panel. Therefore, how to change the stress mode of the concrete surface layer is a technical problem that needs to be solved in the prevention and treatment of such diseases of cement concrete panels. Summary of the invention

[0006] The purpose of the present invention is to improve the semi-space elastic foundation and its stress condition under the concrete pavement panel so as to solve the problems of cracks, broken panels and the like of the concrete pavement panel.

[0007] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0008] On the one hand, the present invention provides a single-lane concrete pavement structure for preventing and controlling center cracking, wherein an anti-cracking groove is opened on the surface of the base layer along the center line of the road, the anti-cracking groove is located below the concrete surface layer, and the interior of the anti-cracking groove is flat and free of fillers.

[0009] Furthermore, a layer of anti-seepage geotextile or film is provided between the anti-cracking groove and the concrete surface layer.

[0010] Furthermore, the width of the anti-crack groove is one third of the width of the concrete surface layer, and the depth of the anti-crack groove is 5-10 cm.

[0011] Furthermore, the anti-crack groove is located at the center below the concrete surface layer, and the length of the anti-crack groove is consistent with the concrete surface layer.

[0012] On the other hand, the present invention provides a construction method for a single lane concrete pavement structure for preventing and controlling center cracking, comprising the following steps:

[0013] Compacting: rolling and compacting the base layer;

[0014] After the grooving and overall rolling of the base layer are completed, loosen the base layer filler within a certain width and depth range of the road centerline;

[0015] Leveling, remove and level the excess base material.

[0016] Furthermore, when grooving, the excavation width is determined along the center line of the road, and the base filler within the range of one-third of the width of the road panel and a depth of 5 to 10 cm on the center line of the road is loosened from top to bottom using a backhoe excavator or manually.

[0017] Furthermore, after the trenching is completed, a layer of anti-seepage geotextile or film is covered on the anti-crack trench, and then the concrete pavement is poured.

[0018] Furthermore, during leveling, the filler in the slot is removed without compaction.

[0019] Beneficial effects: The present invention improves the underlying stress state of the concrete panel, maximizes the bearing capacity of the concrete panel, and solves the problems of cracks, broken panels and other defects of the concrete pavement panel. The method of the present invention is simple to construct, low in construction cost and reliable in effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the specific implementation of the present invention or the technical solution in the prior art, the following will conduct a mechanical analysis and description of the drawings required for the specific implementation or prior art description. The drawings described below are some implementations of the present invention.

[0021] Figure 1 This is a schematic diagram of the stress on the traditional cement concrete panel of a single lane.

[0022] Figure 2 This is a schematic diagram of the stress on a single-lane concrete pavement structure for preventing and controlling center cracking.

[0023] Figure 3 This is the mesh division effect diagram of the loose groove model of the cement concrete pavement base.

[0024] Figure 4 Schematic diagram of the position of the finite element standard load.

[0025] Figure 5 The maximum tensile stress and maximum vertical displacement of a single lane cement concrete slab vary with the width of the loose groove.

[0026] Figure 6 The maximum tensile stress and maximum vertical displacement of the single-lane cement concrete slab vary with the depth of the loose groove.

[0027] Figure 7 This is a graph showing how the maximum tensile stress and maximum vertical displacement of a single-lane cement concrete slab change with axle load. DETAILED DESCRIPTION

[0028] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] like Figure 2 As shown, this example is a single-lane concrete pavement structure for preventing and controlling center cracking. Specifically, an anti-cracking groove is opened on the surface of the base layer along the center line of the road. The anti-cracking groove is located below the concrete surface layer, and the interior of the anti-cracking groove is flat and free of fillers.

[0030] Preferably, a layer of impermeable geotextile or film is provided between the anti-cracking groove and the concrete surface layer.

[0031] Preferably, the width of the anti-crack groove is one third of the width of the concrete surface layer, and the depth of the anti-crack groove is 5-10 cm.

[0032] Preferably, the anti-crack groove is located at the center below the concrete surface layer, and the length of the anti-crack groove is consistent with the concrete surface layer.

[0033] The construction method of the above-mentioned pavement structure is as follows:

[0034] Pre-construction preparations include ensuring smooth construction roads and arranging storage areas for construction machinery and materials.

[0035] After the overall rolling construction of the second base layer is completed, the measurement and positioning are carried out, the leveling and laying out are carried out, and the excavation width is determined along the center line of the road. A backhoe excavator or manual work is used from top to bottom to loosen the base filler within one-third of the road panel width and a certain depth of 5 to 10 cm on the center line of the road.

[0036] Third, use a leveling machine or manually remove and level the excess filler in the loose groove, but do not compact it.

[0037] To prevent leakage of cast-in-place pavement concrete, a layer of impermeable geotextile or film can be covered on the loose groove.

[0038] Fourth, carry out construction and maintenance of concrete road panels according to relevant concrete pavement construction technical specifications.

[0039] Using ANSYS finite element software calculation as the theoretical basis, the model is established as follows Figure 3 As shown in the figure, the load type used in this test is the standard axle load of a single-axle double-wheel group. According to the load stress equivalence principle, the double-circle uniformly distributed load can be converted into a rectangular load to facilitate grid division. The axle weight is 100KN, the tire inflation pressure, that is, the vehicle axle weight is 0.7MPa, and the wheel equivalent contact area is represented by a rectangular area of ​​tire size 0.23m×0.16m. The inner distance between the two wheels is 0.16m, the front and rear wheelbase of the wheels is 2.6m, and the static load position is as follows: Figure 4 shown.

[0040] The loose groove size structure of the single lane cement concrete base is further described in detail below.

[0041] Effect of loose groove width on mechanical response of single lane cement concrete slab structure

[0042] According to the specification, the width of cement concrete surface layer should be 3.0m~4.5m, the length-to-width ratio should be 1~1.35, and the plane area should not be greater than 25m 2 . According to the on-site investigation, the width of the single-lane cement concrete surface layer is 3.5m. The "Highway Cement Concrete Pavement Design Code" stipulates that the length of the cement concrete surface layer should be 4.0m to 6.0m, with a length of 4.0m and a thickness of 0.22m. The width of the loose groove is selected as 1 / 2, 1 / 3, 1 / 4, and 1 / 5 of the plate width respectively. The depth is selected as 10cm. The bending tensile stress and vertical displacement of the overall surface layer slab are selected as the evaluation indicators of the mechanical response of the pavement structure.

[0043] Depend on Figure 5(a) A significant positive correlation can be observed. As the width of the loose groove increases from 0.7m to 1.75m, the maximum tensile stress increases from 0.641MPa to 0.718MPa. The maximum increase in the maximum tensile stress value reaches 8.45%. Figure 5 (b) The maximum vertical displacement shows an inverted V-shaped change. The vertical displacement increases by 0.003mm from 0.7m to 1.17m, and decreases by 0.001mm from 1.17m to 1.75m. In the subsequent design, the width of the loose groove of the single lane concrete base is selected as 1 / 3 of the panel width.

[0044] Effect of loose groove depth in base layer on mechanical response of single lane cement concrete slab structure

[0045] The length of the loose groove is consistent with the normal road surface length, the width is 1 / 3 of the concrete slab width, and the depth is 5cm, 10cm, 15cm, and 20cm respectively. The influence of the loose groove depth on the mechanical response of the single-lane cement concrete slab structure is analyzed, and only the loose groove depth is adjusted while other parameters remain unchanged.

[0046] like Figure 6 As shown in (a), as the groove depth increases from 5 cm to 20 cm, the maximum tensile stress first decreases from 0.665 MPa to 0.662 MPa, and then begins to rise to 0.672 MPa. Figure 6 (b) It can be seen that the change of the loose groove depth has little effect on the maximum vertical displacement of the panel. The maximum vertical displacement changes in the range of only 0.001mm when the loose groove depth ranges from 5cm to 20cm. In the subsequent design, the loose groove depth of the single lane concrete base is selected as 10cm.

[0047] Six different axle loads were selected for the vehicle load size and the wheel pressure was selected from 0.4MPa to 0.7MPa. The corresponding calculation results are shown in Table 1.

[0048] Table 1 Calculation results of tire ground pressure stress under different overload conditions

[0049]

[0050] The axle load increases by 20% of the design standard, and other parameters remain unchanged. The maximum tensile stress σ of the single-lane cement concrete slab with or without loose groove y max and the maximum vertical displacement w L max The calculation results are shown in Table 2.

[0051] Table 2 Calculation results of mechanical response of single lane cement concrete slab as a function of slab length

[0052]

[0053] From Table 2 and Figure 7It can be seen that:

[0054] (1) The axle load has a significant effect on the maximum tensile stress and maximum vertical displacement of the loaded plate. As the design axle load increases from 100KN to 200KN, the maximum tensile stress of the single-lane cement concrete plate is 0.846MPa and the maximum vertical displacement is 3.069mm when the overload rate is 0%. When the overload rate is 100%, the maximum tensile stress of the single-lane cement concrete plate is 1.51MPa and the maximum vertical displacement is 3.839mm. The maximum tensile stress of the loaded plate increases by an average of 12.4%, and the maximum vertical displacement increases by an average of 15.9%. Therefore, overloading has a great influence on the stress and displacement in the pavement structure, and is one of the main factors causing the fracture of cement concrete pavement.

[0055] (2) The loose groove significantly improves the maximum tensile stress and displacement of the single-lane concrete slab under overload. Under different design axle loads, the maximum tensile stress and maximum vertical displacement of the lane concrete slab with loose groove are reduced compared with the single-lane concrete slab without loose groove. The maximum tensile stress is reduced by 0.333MPa, and the average reduction is 28.4%. The maximum vertical displacement is reduced by 0.037mm, and the average reduction is 1.1%. In comparison, the vertical displacement has little effect. Therefore, the loose groove in the base layer can significantly improve the tensile stress of the single-lane concrete slab under overload conditions, and has a certain improvement on the vertical displacement of the single-lane concrete slab.

[0056] The embodiments of this specific implementation are all preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention.

Claims

1. A single lane concrete pavement structure for preventing and controlling center cracking, characterized in that: An anti-crack groove is opened on the surface of the base layer along the center line of the road. The anti-crack groove is located below the concrete surface layer, and the interior of the anti-crack groove is flat and free of fillers.

2. A single lane concrete pavement structure for preventing and controlling center cracking as claimed in claim 1, characterized in that: A layer of anti-seepage geotextile or film is arranged between the anti-crack groove and the concrete surface layer.

3. A single lane concrete pavement structure for preventing center cracking as claimed in claim 1, characterized in that: The width of the anti-crack groove is one third of the width of the concrete surface layer, and the depth of the anti-crack groove is 5-10 cm.

4. A single lane concrete pavement structure for preventing center cracking as claimed in claim 1, characterized in that: The anti-crack groove is located at the center below the concrete surface layer, and the length of the anti-crack groove is consistent with the concrete surface layer.

5. A construction method for a single lane concrete pavement structure for preventing and controlling center cracking, characterized in that: The steps include: Compacting: rolling and compacting the base layer; After the grooving and overall rolling of the base layer are completed, loosen the base layer filler within a certain width and depth range of the road centerline; Leveling, remove and level the excess base material.

6. A construction method for a single lane concrete pavement structure for preventing and controlling center cracking as claimed in claim 5, characterized in that: When trenching, determine the excavation width along the center line of the road, and use a backhoe excavator or manual labor from top to bottom to loosen the base filler within one-third of the road panel width and a depth of 5 to 10 cm along the center line of the road.

7. A construction method for a single lane concrete pavement structure for preventing and controlling center cracking as claimed in claim 5, characterized in that: After the trenching is completed, a layer of anti-seepage geotextile or film is covered on the anti-crack trench, and then the concrete pavement is poured.

8. A construction method for a single lane concrete pavement structure for preventing and controlling center cracking as claimed in claim 5, characterized in that: When leveling, the filler in the groove is removed without compacting.

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