JP2519350B2 - Damping pavement structure - Google Patents

Description

Description: [Object of the Invention] (Field of Industrial Application) The present invention relates to a road pavement structure, and more particularly to a vibration-damping pavement for reducing traffic vibration.

(Prior Art) The vibration generated when a vehicle travels on a road propagates as a surface wave (Rayleigh wave) to the surroundings, but this traffic vibration causes discomfort and insomnia to the residents, and it is used in education, medical care, and industry. The Vibration Control Law sets a requested limit value for reasons such as obstacles. On roads with more traffic vibration, road managers are required to take measures at the request of residents.

It has been clarified that the factors of road traffic vibration include vehicle weight, speed, pavement road flatness (step), pavement structure (embankment, cut), ground softness and structure. There is. As measures on the road side, (a) dig a groove along the vehicle travel route in the propagation route of the surface wave generated when the vehicle travels on the road, and form a surface wave blocking region with air or other material. Generally, a construction method, (b) a construction method for strengthening the structure of the pavement, and (c) a construction method for repairing (overlaying) a new pavement material (generally an asphalt mixture) to improve the flatness of the road surface.

In addition, from the traffic side, the current situation is that vehicle speed restrictions and lane restrictions for large vehicles are also being implemented.

(Problems to be Solved by the Invention) As described above, on the road side, (a),
Although road traffic vibrations are being reduced by the countermeasures of (b) and (c), not only the construction cost is high, but there is still a problem in terms of securing land and maintaining security for (a).

Regarding (b), there are cases in which the roadbed is improved, or the pavement is simply thickened, but in both cases, the effect varies greatly and lacks stability.

Regarding (c), there was a problem that the road condition could be easily restored to the original condition due to shared traffic and could not be maintained stably for a long time.

Therefore, an object of the present invention is to provide a vibration-damping pavement structure capable of stably reducing traffic vibration for a long time.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, in the present invention, the upper surface of an existing road is paved with iron ore having a specific gravity of 4 or more by 50% by weight or more and a density of A heavy asphalt mixture of 3.3 t / m ³ or more is formed in a layer of 3 cm or more.

In addition, in the road pavement structure consisting of the surface layer, the base layer, and the roadbed layer, the curing period is 28
While forming a concrete layer with a compressive strength of 100 kg / m ² or more per day, it contains 50 wt% or more of iron ore with a thickness of 3 cm or more and a specific gravity of 4 or more and a surface with a heavy asphalt mixture with a density of 3.3 t / m ³ or more. Form the layers.

In addition, a thickness of 2 cm on top of the heavy asphalt mixture layer
As described above, an asphalt mixture layer having a density of 1.5 to 2.5 t / m ³ or more is formed.

(Operation) According to such a vibration-damping pavement structure, the heavy asphalt mixture uses at least 50% by weight of iron ore having a specific gravity of 4.0 or more, and the density thereof is usually 3.
It can be increased to 3t / m ³ or more. In this case, if the specific gravity of the iron ore is, for example, about 4.5, the density can be increased to about 4 t / m ³ by the same construction method.

On the other hand, the heavy asphalt mixture has a large mass due to its high density, and has a density of 4 t / m ³
In that case, the thickness effect of the conventional pavement is approximately doubled. As a result, the amount of vibration transmitted from the tires when the vehicle is traveling to the surrounding area is significantly reduced.

(Embodiment) A concrete explanation will be given below with reference to the drawings. Fig. 1 shows a first embodiment in which the upper surface of the existing road 1 contains iron ore having a specific gravity of 4 or more by 50% by weight or more. The weight asphalt mixture layer 3 having a density of 3.3 t / m ³ or more is 3 cm or more.

There are various types of iron ores depending on the mineral composition, the type of minerals, the place of origin, and the like. In addition to the mass of the point of interest of the present invention, it has strength, durability, and weather resistance as road materials. Is desirable. Iron ores can be roughly classified into magnetite and hematite, which can be used in any case, but magnetite which has no chemical change and has a large specific gravity is most preferable.

Note that it is also possible to use magnetite in combination with ferrite having a similar chemical composition and iron ore.

As a result, the vertical vibration acceleration level a in the transverse direction of the road shown in FIG. 4 was observed. As is clear from this observation result, the vibration acceleration level was 4 to 5 dB lower than that before the construction (symbol c). This is a physical quantity of 1 / 1.6-1.
Equivalent to 8. In the section where the asphalt mixture having a thickness of 10 cm and a density of 2.35 t / m ³ was laid on the existing pavement, the effect was only 0 to 2 dB as indicated by the symbol b.

The iron ore of this heavy asphalt mixture is magnetite, adjusted to the particle size shown in Fig. 6, and mixed with asphalt at about 150 ° C by an asphalt plant at the same as the ordinary asphalt mixture, and then by the normal asphalt pavement construction system. It was constructed. The specific gravity of magnetite is 4.853. The composition was 3% by weight of asphalt (stress asphalt 60/80) with respect to 97% of magnetite, and the compaction density was 4.250 t / m ³ . As a result, the Marshall stability is 1050 kg, and the dynamic stability, DS by the wheel tracking test, is 950 times / mm.
was gotten. FIG. 2 shows a second embodiment, which has a heavy asphalt mixture layer 3, a general asphalt mixture layer 7, a concrete layer 9, a roadbed layer 11 and a roadbed 13 from the top, and the roadbed layer 11 has a particle size adjustment. It is composed of an upper layer roadbed 11a made of crushed stone and a lower layer roadbed 11b made of mountain sand.

The concrete layer 9 has a thickness of 15 cm or more and 40 cm or less
On 28th, it is a commercial concrete (slump 3 cm) with a compressive strength of about 100 kg / cm ² or more.

The general asphalt mixture layer 7 is a mixture of coarse aggregate, fine aggregate, filler, and asphalt in a predetermined dense particle size mixing ratio. Heavy asphalt mixture layer 3 has a thickness of 3c
Contains 50% by weight or more of iron ore with a specific gravity of 4 or more at m or more,
It has a density of 3.3 t / m ³ or more.

As a result, as shown in FIG. 5, the structure A using concrete is 5 to 7 dB smaller than the pavement structure B of a general asphalt mixture (1 / 1.8 to 1 / 2.3 in physical quantity), and a great effect was obtained. . Further, in A, the vibration acceleration level is smaller than that in the structure C in which the surface layer is usually an asphalt mixture and the concrete layer is the lower layer, and the effect is clear.

That is, it is known that the vibration damping property of heavy asphalt mixture is higher than that of concrete (for example, application of by-product ferrite to civil engineering, Journal of Japan Society of Civil Engineers, May 1987 issue, P35-40). Due to the interaction between the property and the weight, a vibration low frequency effect is further generated.

In vibration engineering, the ratio (ρ ₁ E ₁ / ρ ₂ E ₂ = α) of impedance (density, ρ × elastic modulus, E) is set to be larger than 1 or smaller than 1 by the following formula due to the multilayer structure. It is well known that vibration reduction can be expected (provided there are two layers).

U = 2Acos (2πf ₁ H / V ₂ ) ・ {cos ² (2πf ₁ H / V ₂ ) + α ² sin ² (2πf ₁ H / V ₂ )} ^-1/2・ exp [i (2πft-ε) ] U: Boundary displacement A: Incident wave amplitude f ₁ : Incident wave frequency H: Layer thickness V ₂ : Wave velocity α: P ₂ V ₂ / P ₁ V ₁ P ₁ : 1 layer density t: Time ε: tan ^-1 α tan ₂ πf · H / V _{2 As} can be judged from now on, the concrete layer 9 below
The effect of using can be theoretically explained.

FIG. 3 shows the third embodiment, which has a density of about 2.0 t / m.
The open-graded asphalt mixture 15 of ³ has a structure having a water permeability that Da設the upper surface of the weight asphalt mixture 3. By investigating the acoustic characteristics of the car running by this, the frequency range (500 to 1000Hz), which is considered to be 2 to 4dB and tire noise before and after construction, in addition to the prevention of water splash due to the permeability of rainwater
A large temperature absorption characteristic was observed. This trial shows that this coating structure has not only vibration characteristics, but also drainage and temperature absorption characteristics, and so-called wide environmental improvement effects can be expected.

[Effects of the Invention] As described above, according to the vibration control pavement structure of the present invention, a great reduction effect of road traffic vibration can be obtained as compared with the conventional case of overlay repair using an asphalt mixture.

Furthermore, by using this heavy asphalt mixture as the surface layer and using the lower concrete layer, a greater effect of reducing traffic vibration is obtained than when using the heavy asphalt mixture layer only for the surface layer and when using the conventional asphalt mixture layer. It is possible to improve the drainage property and the sound absorbing property.

[Brief description of drawings]

FIG. 1 is a sectional view of a pavement structure according to a first embodiment of the present invention,
The figure is a sectional view of the pavement structure in which the concrete layer is provided at the roadbed position of Example 2, FIG. 3 is the pavement structure in which the open-grained asphalt mixture is added to the pavement structure of FIG. 1, and FIG. 4 is the vertical vibration acceleration level. Fig. 5 is a diagram showing the relationship with the transverse distance, Fig. 5 is a diagram showing the relationship between the vertical vibration acceleration level and the transverse distance when a large vehicle runs on a step, and Fig. 6 is an iron ore (magnetite) of an asphalt mixture. It is a particle size distribution map of. 1 …… Existing pavement 3 …… Heavy asphalt mixture layer 9 …… Cement concrete layer 15 …… General asphalt mixture layer

Claims (3)

(57) [Claims] 1. A heavy asphalt mixture containing 50% by weight or more of iron ore having a specific gravity of 4 or more and having a density of 3.3 t / m ³ or more is formed in a layer of 3 cm or more on the upper surface of an existing road pavement. Vibration control pavement structure. 2. In a road pavement structure consisting of a surface layer, a base layer, and a subbase layer, a curing period is 15 cm or more and 40 cm or less below the base layer.
On the 28th, while forming a concrete layer with a compressive strength of 100 kg / m ² or more, 50% by weight of iron ore with a thickness of 3 cm or more and a specific gravity of 4 or more
A vibration-damping pavement structure characterized in that a surface layer is formed from a heavy asphalt mixture having the above content and a density of 3.3 t / m ³ or more. 3. The thickness of the heavy asphalt mixture layer is 2c on the upper surface.
The vibration-damping pavement structure according to claim 1 or 2, wherein an asphalt mixture layer having a m or more and a density of 1.5 to 2.5 t / m ³ or more is formed.