THE RESEARCH ON THE TECHNICAL STATE OF RETAINING WALLS OF HYDRO SCHEMES IN THE JONAVA DISTRICT

Abstract

There are 12 ponds in the Jonava district territory and 3 ponds in the Rukla military base territory. All dams in the district were built in 1978–1989 for irrigation, recreation, fisheries, runoff control or other purposes. 8 earth dams located in the Jonava district were selected for the research. Research aim and objectives:
- to assess the state of retaining walls of Jonava district dams;
- to investigate and assess the state of the Jonava district dams;
- to assess the changes in the concrete strength of concrete and reinforced concrete retaining walls of Jonava district dams.

Methods used to investigate the state of the dams: documentation analysis; visual method; non-destructive method to determine the concrete strength (instrumental), the state was assessed according to the standard methodology specified in the technical construction regulation STR 1.03.07:2017. Based on the investigations’ results, the state of the flood spillway outlet structures (retaining walls) of the hydro schemes of Beržai, Lokys, Šveicarija and Užusaliai ponds in the Jonava district deteriorated the most, with a score of 8.1–9.2. According to the technical state assessment (carried out following STR 1.07.03:2017) results, reconstruction works are necessary for the Beržai, Lokys, Šveicarija and Užusaliai hydro schemes in the Jonava district, and repair works are necessary to eliminate the defects and damage in the hydro schemes of the Jonava city ponds I–IV. Based on the investigations’ results, it was found that the concrete of the retaining walls of the Beržai, Užusaliai, Jonava I and II hydro schemes has weakened the most, at least by one strength class, when comparing the results of investigations done in 2017 and 2020 with the results of 2023 investigations. In the other hydro schemes, the concrete of the retaining walls weakened less.