Practice of geo-radar research in the Republic of Kazakhstan

The article considers the issues of applying ground penetrating radar (GPR) technologies for engineering purposes concerning subsurface research. It describes the field of application of GPR research during road construction and operation and the advantages and disadvantages of this type of engineering survey. It presents comparative data on the accuracy (inaccuracy) of existing GPR control methods applied to determine the thickness of the monolithic pavement layers in Europe, CIS, and the USA. The main provisions of the GPR survey procedure are described, including four main stages: the analysis of initial materials of surveyed section and equipment preparation; GPR survey; geological verification; processing and interpreting of radargrams; and the preparation of a report. Geophysical works were performed using the geo-radar of the OKO series as part of the road measuring complex DVK-05 on the section of the Astana-Petropavlovsk A-1 highway with cement concrete pavement and on the section of the R-12 "Kokshetau - Atbasar" with asphalt pavement. The example of a radargram and the core sample of a cement concrete pavement taken during geological verification of the thickness of a monolithic layer is presented. Graphs of variation in the thickness of pavement layers by radargrams of longitudinal passages in the indicated road sections with the assumptions about the nature of the heterogeneity of the obtained values are given. The obtained results on the thickness of monolithic layers (cement concrete and asphalt concrete) were assessed on the criteria of quantitative deviation from the required standard value. Recommendations were provided to address positive deviations in the thickness of monolithic pavement layers at various stages of the road survey.