RU2399715C1 - Pavement surfacing design - Google Patents

Abstract

FIELD: personal use articles.

SUBSTANCE: pavement surfacing design consists of a multilayer base, which includes drainage layer and two layers of principal material, and the upper and lower layers of asphalt concrete pavement. The thickness layers of pavement are selected in accordance with the thickness and density of the upper layer of asphalt concrete pavement, as well as the density of the layer by the following functional dependence: h_j=(-0.342i⁴+4.004i³-15.659i²+24.413i-11.417)*h₁*ρ₁/ρ_i, where i - is the serial number of the layer, ρ_i - is density of the i-layer, h₁ and ρ₁ - are thickness and density of the upper layer of the coating.

EFFECT: increase of operational integrity and durability of non-rigid multilayer pavement surfacing.

1 tbl, 3 dwg

Description

The invention relates to the construction of roads, namely, the construction of pavement.

Known designs of multilayer non-rigid pavements, consisting of various combinations of thicknesses and materials of the base layers and asphalt concrete pavement.

A known construction of pavement, including a base made of crushed stone and highly porous asphalt concrete and a two-layer asphalt concrete pavement with a thickness of the lower layer of 50 mm and an upper layer of 40 mm (Road asphalt concrete / L.B.Gezentsvej, N.V. Gorelyshev, AMBoguslavsky, I. V. Korolev under the editorship of L.B.Gezentsvei - 2nd ed., Revised and additional - M: Transport, 1985, p. 292).

A known construction, including a base in the form of a drainage layer, a crushed stone layer of low-strength limestone, gravel and a layer of coarse-grained asphalt concrete, on which is placed a coating of asphalt concrete with a surface treatment layer of black crushed stone-wedge with a grain size of up to 10 mm (see RF patent No. 2332535, IPC E01C 7/18, published on 08.27.2008).

Also known is the construction of pavement, including a base of re-compacted soil with a two-layer coating of asphalt concrete (see RF patent No. 2310031, IPC E01C 3/04, publ. 10.11.2007).

These analogues have a common drawback, namely the fact that the operational performance and durability of the pavement are significantly lower than the design parameters. This leads to the need for premature repairs. This is due to the fact that pavement designs are characterized by a high level of vibrational forces in the layers, which is one of the main causes of the destruction of pavements.

A known construction of pavement adopted as a prototype, consisting of a draining sand layer 30 cm thick, a layer of gravel mix 12 cm thick, a layer of crushed stone treated with cementitious materials, 8 cm thick, a layer of coarse porous asphalt concrete with a thickness of 6 cm and a fine-grained, dense coating asphalt concrete 5 cm thick (see Typical building constructions, products, units. Series 3.503-71. Road clothes of public roads. Design materials. P.53).

A disadvantage of the known structures, including the prototype, is the insufficient strength associated with an increased level of vibrational forces and vibration of the layers due to the lack of out-of-phase movements of adjacent layers that could damp each other's vibrations.

The technical problem solved by the invention is to reduce the level of vibrational forces in the layers of the pavement and, as a result, increase the performance and durability of the pavement.

The solution of the technical problem is achieved by the fact that in the construction of pavement, consisting of a multilayer base, including a drainage layer and two layers of carrier material, and the upper and lower layers of the asphalt concrete pavement, according to the invention, the thicknesses of the pavement layers are selected in accordance with the thickness and density of the upper layer asphalt concrete pavement, as well as the density of the corresponding layer according to the following functional dependence:

h _i = (- 0.342i ⁴ + 4.004i ³ -15.659i ² + 24.413i-11.417) h ₁ · ρ ₁ / ρ _i ,

where i is the sequence number of the layer; ρ _i is the density of the i-th layer; h ₁ and ρ ₁ - thickness and density of the upper coating layer.

The solution of the technical problem is due to the fact that in the process of occurrence of fluctuations in the layers of pavement, the oscillatory movement of adjacent layers that occurs after passing through automobile transport occurs in antiphase. Antiphase is provided by a certain ratio of the natural frequencies of the layers of the pavement, achieved by designing the thicknesses according to the proposed functional dependence. With the antiphase motion of adjacent layers, they mutually damp vibrations, which leads to a decrease in the level of destructive dynamic forces and an increase in the working capacity and durability of pavements.

The invention is illustrated by drawings, where figure 1 shows a multilayer construction of pavement; figure 2 presents the calculated vibrational spectrum of vibrational forces implemented in the design of pavement of the prototype; and figure 3 is the same for the proposed design of pavement. Figures 2 and 3 show the spectra of dynamic forces F = f (t) in the upper coating layer of dense asphalt concrete (solid line) and in the lower coating layer of porous asphalt concrete (dashed line), where t is the time.

The design of the pavement consists of an asphalt concrete pavement and a base (not indicated in the drawing). Asphalt concrete coating consists of upper and lower layers 1 and 2, respectively. Moreover, the upper layer 1 consists of a layer of dense asphalt concrete, and the lower layer 2 is made of porous asphalt concrete. The base includes two layers of carrier material in the form of layer 3 of black crushed stone and layer 4 of fractionated crushed stone, as well as a drainage layer 5.

Each of the i-layers 2, 3, 4, 5 of the pavement structure is characterized by a thickness h _i , ρ _i. Moreover, the thickness h _{i is} selected in accordance with the thickness h ₁ , density ρ _{1 of the} upper layer of the asphalt concrete pavement and density of the i-th layer.

Selection is carried out according to the following functional dependence:

h _i = (- 0.342i ⁴ + 4.004i ³ -15.659i ² + 24.413i-11.417) * h ₁ * ρ ₁ / ρ _i ,

where i is the sequence number of the layer; ρ _i , is the density of the i-th layer; h ₁ and ρ ₁ - thickness and density of the upper coating layer.

The proposed functional dependence was derived by calculation on the basis of the optimal ratio of the natural frequencies of the layers of the pavement, taking into account the inertia of the layers and the process of developing vibrations from top to bottom in the road structure. The necessary set of natural frequencies distributed over the layers of the pavement was approximated by a polynomial dependence. Since the vibration frequencies are functions of the masses and stiffnesses of the layers of the pavement, the masses and stiffnesses were also distributed among the layers and their polynomial approximation. The corresponding mathematical transformation was obtained the desired functional dependence for calculating the thicknesses of the pavement layers of the structure under consideration.

The design parameters of the pavement of the prototype and the invention are presented in the table.

Table Layer number Thickness cm Density, kg / m ³ prototype invention one 5,0 5,0 2400 2 6.0 6.9 2300 3 8.0 7.8 2000 four 12.0 29.3 1800 5 30,0 38,4 1850

For comparison, we calculated the dynamic forces arising in these structures after passing a truck at a speed of 90 km / h. The spectra of dynamic forces shown in FIG. 2 and FIG. 3 in two adjacent coating layers show that the number of antiphase movements in the prototype does not exceed 59%, while in the construction according to the invention this value is 88%. The calculation of the average dynamic forces in the coating according to these spectra reveals that in the proposed design of pavement these forces are approximately 2 times less than that of the prototype. So, in the prototype, in the layer of dense asphalt concrete, the average dynamic forces are 5.7 kN, in the layer of porous asphalt concrete - 8.2 kN. In the structure according to the invention, these forces are 2.7 kN and 4.0 kN, respectively.

Thus, the invention, by selecting the optimal ratio of the thicknesses of the layers, carried out by calculation according to the functional dependence, allows to reduce the level of vibrational forces in the layers of the pavement, which leads to an increase in the working capacity and durability of the pavement.

Claims (1)

The construction of pavement, consisting of a multilayer base, including a drainage layer and two layers of carrier material, and the upper and lower layers of asphalt concrete pavement, characterized in that the thicknesses of the layers of pavement are selected in accordance with the thickness and density of the upper layer of asphalt pavement, as well as the density of the corresponding layer according to the following functional dependence:
h _i = (- 0.342i ⁴ + 4.004i ³ -15.659i ² + 24.413i-ll, 417) h ₁ · ρ ₁ / ρ _I ,
where i is the sequence number of the layer; ρ _i is the density of the i-th layer; h ₁ and ρ ₁ - thickness and density of the upper coating layer.

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