A distinctive feature of the developed approach is its high productivity, informative content and the absence of the need to select cores from the pavement of the highway.
The method combines instrumental measurements with the use of modern diagnostic shock loading units of the FWD type and mathematical modeling necessary to compare the ideal calculated deformation pattern with the results of field observations.
– The FWD shock loading unit is equipment for measuring the strength of highways, is a two-axle semi-trailer, on which a shock loading mechanism is mounted, reproducing the load corresponding to a classic vehicle, as well as a beam with geophone sensors located every 30 cm as you move away from the loading point, which allow you to register vertical deformation at a distance of up to 2.1 m from the impact point," explained Artem Tiraturyan.
As a result, it is possible to obtain the values of the actual stiffness of the asphalt concrete layer, the base layer and the working soil layer of the roadbed, which can be compared with the project and, in case of their deviation to the lesser side, assign repair measures aimed at improving those components and indicators that determine its overall strength characteristics on the road section under study.
According to Artyom Tiraturyan, a mathematical model developed jointly with the Department of Information Systems in Construction of DSTU simulates a similar design on a computer – the so-called calculated deflection bowl. The model allows you to set all the parameters necessary for calculations: the thickness of asphalt concrete layers, bases and soils.
– The peculiarity of the model is that it is built based on idealized parameters – the mechanical properties of each layer. At the end of the procedure, the calculated indicators are superimposed on the experimental ones," said Artem Tiraturyan.
The results of the study allow us to determine with which layer the problem has arisen and how it can be solved.
– For example, in case of a fall in the rigidity of the base, the overlap of the asphalt concrete layer will not be effective: in about a year the same defects will return. Until the problem with the soil is solved, replacing the base will not lead to the expected results. The soil may be waterlogged, or the operation of the drainage system may be disrupted," commented Artem Tiraturyan.
Conceptually, the idea of the approach implemented by DSTU scientists is not new, it has long been a well-known problem related to the inverse class. The main novelty of the solution is in the field of applied computational algorithms, which are not inferior, and in many ways surpass well–known world practices in this field.
The results have already been obtained that allow us to bring the applied technique to a qualitatively different level – to analyze the entire process of deformation of the pavement for a period of time corresponding to the contact of the car wheel with the coating.
The research is carried out within the framework of the grant from the President of the Russian Federation for state support of young Russian scientists - candidates of sciences (agreement № 075-15-2022-584).