RU2405882C1 - Method for forecasting of condition of motor roads with asphalt coats and assignment of justified timings of repair works - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: thermal properties of asphalt coat are determined, namely, specific heat capacity C_h, free energy increment δF, coefficient of free energy deficit k_def, besides, initial value is value of specific heat capacity of asphalt coat in the beginning of operation, and change of this value is monitored in process of operation, curves of specific heat capacity and increment of free energy dependence on time are periodically built, starting from initial values with account of reference points, at the same time free energy deficit increment is determined, using the following formula:

where m - value that is numerically equal to material density, mass dimension, g; T - temperature of coat material (in calculations T=20°C), °C;

-initial value of C_h, J/(kg·°C); then free energy deficit coefficient k_def is calculated using the following formula:

, where \δF\ - module of free energy increment at this moment of time, δF_max - maximum value of this increment for the period of operation; k_def is considered as criterion that determines timing of repair works completion, and if current value k_def(t) is higher than rated value

i.e.

conclusion is made on the necessity to perform repair works. Besides rated value of free energy deficit coefficent

in the beginning of operation is accepted within the limits of numerical values from 3 to 6, depending on conditions of road surface operation and type of asphalt, and current specific heat capacity C_h is determined at least once a year; at the same time after each other operating stage, when selecting technology of repair works, rated value of free energy deficit coefficient is determined at the moment of another repair completion, which has a trend of decreasing (not increasing) compared to previous value, and limits of specific heat capacity C_h with time take values from 975 to 1578 J/(kg·°C), depending on conditions of road surface operation and type of asphalt.

EFFECT: increased efficiency of forecasting condition of motor roads with asphalt coats and assignment of justified timings of repair works.

5 cl, 2 dwg

Description

The invention relates to the field of diagnostics and assessment of the condition of roads with asphalt concrete coatings, namely, to predict the condition of asphalt concrete pavement and the appointment of reasonable terms for repair work.

There is a method for predicting the condition of roads with asphalt concrete pavement, which determines the evenness of the asphalt concrete pavement and judging the deterioration of the evenness state of the operational and technical condition of the asphalt concrete pavement (ODN 218.1.052-2002. Strength assessment of non-rigid pavements (instead of VSN 52-89). - M .: Informavtodor, 2002, - 65 p.).

However, this method is not effective enough, since the evenness indicator is only an external manifestation of the internal processes occurring in the road surface, and only indirectly evaluates its condition, without indicating a residual resource.

The closest in technical essence and the achieved effect is a method for predicting the status of asphalt concrete pavement, which determines the degree of strength as the ratio of the actual elastic modulus of the coating material to the calculated one (ODN 218.0.006-2002. Rules for the diagnosis and assessment of the condition of roads (instead of VSN 6-90 ). - M.: Informavtodor, 2002, - 139 p.)

However, this method of predicting the status of asphalt concrete pavement is not effective enough and does not provide a reasonable assignment of the overhaul life of an asphalt concrete pavement, since the dynamics of cumulation of residual deformations, changes in the ratio of the residual and elastic components of compression deformation during aging of the pavement are not taken into account. Since under actual operating conditions, the asphalt concrete pavement undergoes multiple stresses with the accumulation of residual deformations.

The objective of the invention is to increase the efficiency of forecasting the condition of roads with asphalt concrete pavements and the appointment of reasonable terms for repair work on asphalt concrete pavements.

This is achieved by the fact that in the method for predicting the condition of roads with asphalt concrete pavements and assigning reasonable terms for repair work on asphalt concrete pavements, according to which the strength coefficient is determined equal to the ratio of the actual elastic modulus of the asphalt concrete pavement to the calculated (required) one, while the thermal properties of the asphalt concrete pavement are determined, namely, the specific heat _Cm free energy increment δF, the free energy deficit ratio k _dEF, wherein as the initial value, take the specific heat capacity of the asphalt concrete coating at the beginning of operation and monitor the change in this value during operation, plot the specific heat and the increment of free energy versus time, based on the initial values taking into account reference points, and determine the increment of the free energy deficit according to the formula

- начальное значение величины С_т, Дж/(кг·°С);where μ is a quantity numerically equal to the density of the material, the dimensions of the mass, g; T is the temperature of the coating material (in the calculations T = 20 ° C), ° C;

- the initial value of the quantity C _t , J / (kg · ° C);

then calculate the coefficient of deficit of free energy k _def according to the formula

,

,

- модуль приращения свободной энергии в данный момент времени, δF_max - максимальное значение этого приращения за период эксплуатации; k_деф рассматривают как критерий, определяющий срок производства ремонтных работ и при текущем значении k_деф(t) больше нормативного значения

, то есть

, делают заключение о необходимости проведения ремонтных работ.Where

is the free energy increment modulus at a given moment in time, δF _max is the maximum value of this increment during the operation period; k _{def is} considered as a criterion that determines the period of repair work and at the current value of k _def (t) is greater than the standard value

, i.e

, make a conclusion about the need for repairs.

, в начале эксплуатации принимают в пределах числовых значений от 3 до 6, в зависимости от условий эксплуатации дорожного покрытия и типа асфальтобетона, а текущую удельную теплоемкость С_т определяют не реже одного раза в год; при этом после каждого эксплуатационного этапа при выборе технологии ремонтных работ определяют нормативное значение коэффициента дефицита свободной энергии на момент окончания очередного ремонта, которое имеет тенденцию к уменьшению (невозрастанию) по сравнению с предыдущим значением, а пределы удельной теплоемкости С_т от времени принимают значения от 975 до 1578 Дж/(кг·°С), в зависимости от условий эксплуатации дорожного покрытия и типа асфальтобетона.Moreover, the normative value of the coefficient of deficit of free energy

, at the beginning of operation, they are accepted within the range of numerical values from 3 to 6, depending on the operating conditions of the road surface and the type of asphalt concrete, and the current specific heat capacity С _t is determined at least once a year; in this case, after each operational stage, when choosing a technology for repair work, the standard value of the coefficient of free energy deficit at the time the next repair is completed is determined, which tends to decrease (not increase) compared to the previous value, and the specific heat limits С _t take values from 975 from time to time up to 1578 J / (kg · ° С), depending on the operating conditions of the road surface and the type of asphalt concrete.

A comparative analysis with the prototype shows that in the claimed method, the thermophysical characteristics of the asphalt concrete coating are determined, namely, specific heat C _t , increment of free energy δF, coefficient of free energy deficit k _def , and the specific heat capacity of asphalt concrete coating at the beginning of operation is taken as the initial value and control the change in this value during operation, build graphs of the specific heat and the increment of free energy over time based on the initial values, taking into account the reference points, this determines the increment of the free energy deficit according to the formula

,

,

- начальное значение величины С_т, Дж/(кг·°С);where μ is a quantity numerically equal to the density of the material, the dimensions of the mass, g; T is the temperature of the coating material (in the calculations T = 20 ° C), ° C;

- the initial value of the quantity C _t , J / (kg · ° C);

then calculate the coefficient of deficit of free energy k _def according to the formula

,

,

, делают заключение о необходимости проведения ремонтных работ.where | δF | is the free energy increment modulus at a given moment in time, δF _max is the maximum value of this increment during the operation period; _{kdef is} considered as a criterion that determines the period of repair work and at the current value of _kdef (t) is greater than the standard value of _kdef (t), i.e.

, make a conclusion about the need for repairs.

в начале эксплуатации принимают в пределах числовых значений от 3 до 6, в зависимости от условий эксплуатации дорожного покрытия и типа асфальтобетона, а текущую удельную теплоемкость С_т определяют не реже одного раза в год; при этом после каждого эксплуатационного этапа при выборе технологии ремонтных работ определяют нормативное значение коэффициента дефицита свободной энергии на момент окончания очередного ремонта, которое имеет тенденцию к уменьшению (невозрастанию) по сравнению с предыдущим значением, а пределы удельной теплоемкости С_т от времени принимают значения от 975 до 1578 Дж/(кг·°С), в зависимости от условий эксплуатации дорожного покрытия и типа асфальтобетона.Moreover, the normative value of the coefficient of deficit of free energy

at the beginning of operation, they are accepted within the range of numerical values from 3 to 6, depending on the operating conditions of the road surface and the type of asphalt concrete, and the current specific heat capacity С _t is determined at least once a year; in this case, after each operational stage, when choosing a technology for repair work, the standard value of the coefficient of free energy deficit at the time the next repair is completed is determined, which tends to decrease (not increase) compared to the previous value, and the specific heat limits С _t take values from 975 from time to time up to 1578 J / (kg · ° С), depending on the operating conditions of the road surface and the type of asphalt concrete.

Thus, the claimed technical solution meets the criterion of "NOVELTY."

A comparison of the proposed method with other technical solutions shows that there is a known method for predicting the condition of roads with asphalt concrete pavements, which determine the evenness of the asphalt concrete pavement and judge the operational and technical condition of the asphalt concrete pavement by deterioration of the evenness (ODN 218.1.052-2002. Strength assessment of non-rigid road clothes (instead of VSN 52-89). - M .: Informavtodor, 2002, - 65 p.).

However, this method is not effective enough, since the evenness indicator is only an external manifestation of the internal processes occurring in the road surface, and only indirectly evaluates its condition, without indicating a residual resource. This allows us to conclude that the technical solution meets the criterion of "INVENTIVE LEVEL".

An example embodiment of the invention.

In the method for predicting the condition of an asphalt concrete pavement, in addition to the physicomechanical characteristics of the material of the asphalt concrete pavement (density, elastic modulus, adhesion coefficient), thermal properties are also determined (measured and calculated): specific heat capacity, free energy deficit coefficient. Moreover, the value (value) of specific heat at the beginning of operation is taken as a basic parameter, this value is monitored during operation at least once a year, after which, taking into account the reference points, graphs of the specific heat and free energy variation versus time are constructed. Then determine the current value of the coefficient of deficit of free energy. When the inequality is fulfilled, when the current value of the coefficient of free energy deficit becomes more than the normative, they make a conclusion about the need for repair work, the type and technological features of which are determined after additional visual research and economic opportunities.

Upon completion of the construction of the road asphalt concrete pavement, the initial (initial) value of the base value of its material is determined - specific heat in accordance with the requirements of GOST 23250-78 (GOST 23250-78. Building materials. Method for determining specific heat. - M .: Publishing house of standards, 1979, - 8 p.).

The initial value of the density of the material of the road surface and the total change in flatness are also determined. The values of these two values must satisfy the normative values.

Using the recommended algorithms (MA Zavyalov, Thermodynamic theory of the life cycle of road asphalt pavement: Monograph. - Omsk: SibADI, 2007, - 283 pp.), Using the Mathcad software product, the initial values of the values needed to monitor and predict the state of the pavement and appointment of reasonable terms for repair activities. Values are placed in a table. For example:

Quantities Type of asphalt concrete fine-grained dense asphalt concrete, type A, grade I (road category 1-B) fine-grained dense asphalt concrete type B, grade I (road category I-A) specific heat, J / (kg · ° С) 1047 980 ductility coefficient one one density, kg / m ³ 2650 2500 technological coefficient 0.2 0.19 modulus of elasticity, MPa 3120 2700 variation of free energy, J 2100 2400 normative coefficient of free energy deficit 3.14 3.75 coated wheel grip 0.6 0.65

The elastic modulus of the coating material is calculated from the following expression

,

,

where ρ is the density of the material; g is the acceleration of gravity; h is the thickness of the pavement layer; k _{T, V} = d (lnT) / dV = dT / (TdV), numerical values of k _{T, V} are taken from the tables of work (Zavyalov M.A. Thermodynamic theory of the life cycle of road asphalt concrete pavement: Monograph. - Omsk: SibADI, 2007 . - S.218-221] T - temperature, V - volume, t - time; t ₀ - initial time.

These values are also entered in the operational passport of the road. In the process of monitoring the state of the material of the road surface in order to correct the current values characterizing this state, the value of the specific heat of the material is periodically determined experimentally. Considering the obtained value of the specific heat capacity as a reference point, the dependences of the specific heat on the operating time are adjusted based on the analysis of their quasilinearity in the reference points. Such correction is carried out at least once a year.

In Fig. 1, the graphs of the dependences of specific heat and free energy variations on time are plotted based on the initial values indicated in the table with reference points. The following time dependences are given (FIG. 1): 1 and 2 — free energy variations, J; 3 and 4 - the specific heat, J / (kg · ° C), for road asphalt pavements, considered in the table, respectively; 5 - the value of specific heat, built taking into account the reference points; 6 and 7 — theoretical and “adjusted” coefficient of free energy deficit (in Fig. 1 - the left scale; for clarity of the image, the coefficient value is multiplied by 10 ³ ).

It is established that the time point for the start of repair work is characterized by a deficit of free energy, its negative increment. The free energy increment F of the coating material is calculated from the following expression (MA Zavyalov, Thermodynamic theory of the life cycle of road asphalt concrete pavement: Monograph. - Omsk: SibADI, 2007, - 283 p.)

,

,

- начальное значение величины С_т.where C _t - specific heat; μ is a quantity numerically equal to the density of the material, the dimensions of the mass, T is the temperature,

- the initial value of C _t.

, рассматривается как нормативный критерий, определяющий срок производства ремонтных работ. Иначе говоря, момент времени, в который текущее значение k_деф(t) становится больше нормативного значения

, то есть

.The introduced coefficient of free energy deficit, equal to the ratio of the absolute value of the increment of free energy at a given time to the maximum value of this increment for the entire period of operation

, is considered as a normative criterion that determines the period of repair work. In other words, the point in time at which the current value of k _def (t) becomes greater than the standard value

, i.e

.

The normative value of the coefficient of free energy deficit is obtained within numerical values from 3 to 6, depending on the operating conditions of the road surface and the type of asphalt concrete (figure 2). For example, the coefficient of free energy deficit for asphalt concrete of type A and the first category takes a value close to the left border, for porous asphalt concrete and the second category of road to the right border.

и

.In figure 2. the dependence of the coefficient of free energy deficit k _def on the operating time of the coating is constructed. The following cases were considered: 1 - coarse-grained porous asphalt concrete grade II (road category I-B, traffic intensity of 7-10 thousand aut./day); 2 - fine-grained dense asphalt concrete of type A, grade I (road category I-B, traffic intensity of 15-20 thousand aut./day); 3 - fine-grained dense asphalt concrete of type B, grade I (road category IA, traffic intensity> 20 thousand aut./day); 4 - fine-grained dense asphalt concrete of type B, grade I (road category II, traffic intensity of 5-7 thousand aut./day). For lines 1 and 2, the values of the normative deficit coefficient are calculated, respectively

and

.

Make a conclusion about the need for repair work, the type and technological features of which are determined after additional visual research and economic opportunities. Wherein:

- after each operational stage, when choosing a technology for repair work, the standard value of the coefficient of free energy deficit at the time of the end of the next repair is determined, which tends to decrease (not increase) compared to the previous value, and therefore, the design life after each repair is also reduced;

- there comes a time when the coefficient of free energy deficit assumes obviously low values and to carry out repair work, starting from the construction stage, becomes impractical and economically unprofitable; it is necessary to return to the design phase again.

Thus, the proposed method can improve the efficiency of forecasting the condition of roads with asphalt concrete pavements and the appointment of reasonable terms for repair work.

Claims (5)

1. A method for predicting the condition of roads with asphalt concrete pavements and assigning reasonable terms for repair work, which determine the strength coefficient equal to the ratio of the actual elastic modulus of the asphalt concrete pavement to the calculated (required) one, characterized in that the thermal properties of the asphalt concrete pavement are determined, namely, specific heat C _t , increment of free energy δF, coefficient of deficit of free energy k _def , and take as the initial value the specific heat capacity of the asphalt concrete pavement at the beginning of operation and monitor the change in this value during operation, build graphs of the specific heat and the increment of free energy over time, based on the initial values taking into account reference points, while determining the increment of the free energy deficit by the formula:

where µ is a quantity numerically equal to the density of the material, the dimensions of the mass, g;
T is the temperature of the coating material (in the calculations T = 20 ° C), ° C;
FROM

- the initial value of the value of C _t , J / (kg · ° C),
then calculate the coefficient of free energy deficit k _def according to the formula:

,
where | δF | - module increment of free energy at a given time;
δF _max - the maximum value of this increment for the period of operation,
k _{def is} considered as a criterion that determines the period of repair work, and at the current value of k _def (t) is greater than the standard value k

, i.e., k _def (t)> k

, make a conclusion about the need for repairs. 2. A method for predicting the condition of roads with asphalt concrete pavements and the appointment of reasonable terms for repair work according to claim 1, characterized in that the standard value of the coefficient of free energy deficit k

at the beginning of operation, they are accepted within the range of numerical values from 3 to 6, depending on the operating conditions of the road surface and the type of asphalt concrete. 3. A method for predicting the condition of roads with asphalt concrete pavements and the appointment of reasonable terms for repair work according to claim 1, characterized in that the current specific heat capacity C _t is determined at least once a year. 4. A method for predicting the condition of roads with asphalt concrete pavements and assigning reasonable terms for repair work according to claim 1, characterized in that after each operational stage, when choosing a technology for repair work, the normative value of the coefficient of free energy deficit at the time of completion of the next repair is determined, which has a tendency to decrease (non-increase) in comparison with the previous value. 5. A method for predicting the condition of roads with asphalt concrete pavements and assigning reasonable terms for repair work according to claim 1, characterized in that the specific heat limits С _t take values from 975 to 1578 J / (kg · ° C) depending on the conditions operation of the road surface and type of asphalt concrete.

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