Contains a model for assessing the technical condition of pavement, based on the main working hypothesis of the study on the existence of a functional relationship between the results of instrumental diagnostics of pavement, including electro-physical parameters of pavement materials and pulse signals of GPR, and road pavements design strength and reliability characteristics. The proposed model is based on: methods of GPR diagnostics of pavement; methods of numerical modeling of stress-strain state (SS-state) of the pavement construction; statistical and probabilistic methods for assessing the technical condition of the pavement structure. The solution of the problem of detection, positioning and identification of subsurface cracks in the layers of pavement is proposed and criteria for assessing the technical condition of pavement - technical condition index by involving the theoretical and probabilistic approach and methods of statistical processing of instrumental measurements, which allowed to take into account variations in the parameters of pavement layers, heterogeneity of stress-strain and assess the reliability of pavement design.
Laboratory experiments and tests on public roads confirmed the theoretical provisions of the method of assessing the technical condition of non-rigid pavement, which involves the results of GPR diagnostics, and proved the adequacy of the developed models. The relative error in determining the depth of the cracks is from 1 % to 7 %.
According to the results of numerical modeling of SS-state of the pavement structure, it was possible to establish: the most dangerous position of the load relative to the through and hidden crack; the crack opening width and the minimum modulus of elasticity of the crack filling material, which reduces the tensile stresses on the soft fiber of the package of upper pavement layers. The connection between the indicators of heterogeneity of the pavement structure, are determined by the results of GPR diagnostics and numerical modeling, the index of the technical condition of the pavement structure and its limit values. Limit values of coefficient of variation and index of technical condition of road construction for roads of different categories are determined, based on the provisions of reliability theory, risk theory and regulatory documents requirements and allow to determine the reliability of road pavements with cracks in the upper layers and reinforced base layers.
Methods of GPR diagnostics and assessment of technical condition of non-rigid pavements with the use of GPR sounding data are developed. The practical method of searching, positioning and identification of the subsurface cracks in the upper layers of non-rigid pavement includes the procedure for GPR survey and processing of the pulsed signals of GPR during solving the problems of defectoscopy of non-rigid pavements. The method of assessing the condition of non-rigid pavement using GPR sounding data is based on the results of GPR diagnostics and numerical simulation of SS-state of non-rigid pavement with cracks in the upper layers and reinforced base layers and allows to assess the technical condition of pavement design taking into account its heterogeneity state; risk of destruction; reliability of construction of road pavements; the coefficient of variation of the pavement technical condition index.
The expected economic effect of reducing the cost of inspection of non-rigid pavement due to the use of non-destructive method of GPR diagnostics is 690.04 UAH / km. If the volume of surveys reaches 100 km / year, the expected economic effect from the introduction of the method of GPR diagnostics will be 455,004 thousand UAH / year 100 km. The potential economic effect of the introduction of the method of assessing the technical condition of pavement with the use of GPR sounding data is provided by reducing transport and operating costs (293,754 thousand UAH / km year), increasing the service life of pavement due to the completeness of GPR diagnostics, the ability to assess structural reliability road clothing.
Key words: construction of non-rigid pavement, technical condition, subsurface crack, GPR, diagnostics, technical condition index, coefficient of variation, reliability.
