The dissertation work presents a new solution to the topical questions of the method of forecasting the humidity-like mode of the drainage of the road construction layer under the action of the super-normative load. A brief analysis of the proposed outline of the year-round cycle of the water-thermal regime of the pavement of roads is given. For each period, different types of humidification have been identified, which make the maximum contribution to the water supply to the drainage layer. In order to eliminate, in a timely manner, the factors changing road conditions by increasing the volume of heavy traffic, it is necessary to forecast the humidity of the drainage construction (DC).
Considering this, a study was made of the drainage layers on the experimental installation of a road structure conforming to the parameters of the category III road. The work of two types of drainage structures was studied: with crushed and sandy layers, with filtration coefficients of 100 m / day and 4.5 m / day, respectively. The operating mode of two types of shallow drainage constructions differed: a draining layer made of soap rubble, fr. 20-40 mm, had an average discharge intensity of 0.0645 l / min, and a medium grain sand layer of 0.0029 l / min. A shallow, sandy drainage structure was seen as working on a drying principle, but actually worked on a absorption principle.
To forecast the volume of water entering the drainage layer due to heavy vehicle loads and the corresponding change in the humidity of the entire road structure during the most unfavourable period of the year, the characteristics describing this process have been defined. Accordingly, the process of soil drying during thawing and drying was analysed.
A three-dimensional road construction model with a draining layer by finite elements is provided for carrying out a numerical experiment. The software-calculation suite SCAD Office has been chosen to create a calculation model of the elements of the road. Road models of categories I-IV were constructed along the boundary of the extreme lane with a shoulder and slope 1:1.5 gradient. The construction of the finite-element grids is conditioned by the size of the wheel stamp on the statistical load of the A2 group, which is regulated by state standards. To obtain the most possible deformations for carrying out numerical experiments, it is decided not to limit the movement of the nodes along the contour of the model.
For roads of categories I to IV in the conditions of the 1st road-climatic zone of Ukraine, with the over-normative load from the wheel of the design car 86.25 kN on the road structures with the wetted sandy drainage layer, The migration of moisture from the bottom upwards will occur from the soil of the subgrade to the carriageway, from the thickness of 50 to 80 cm, from the shoulder to the thickness of 60 to 90 cm, depending on the overall thickness of road pavement; the proportion of the excess pressure applied to the water pressure varies from 5.4 to 7.4 litres per m2.
The work also presents the results on the effectiveness of the methodology for taking project decisions on the selection of parameters of structures for water and thermal regulation. The proposed updated method makes it possible to eliminate the stages of the collection of baseline data on the climatic conditions of the construction area over the many years of observation (air temperature, soil, wind speed and snow height) and statistical processing of these data in order to perform the calculations according to the normative method. All these elements of the design can be replaced by the simplified use of maps of the calculated freezing depth of the road structure for different road categories. On the basis of the completed cluster analysis, a road-climate map was constructed on which the territory of Ukraine is divided into five zones. The introduction of the results of the development makes it possible to optimize the parameters of the shallow drainage structure (including the thickness of the drainage layer) taking into account changes in climatic characteristics.
The proposed definition of the reserve thickness of the draining layer for accommodating the additional excess water due to the squeezing thereof under the influence of the super-normative load is proposed.
