ANALYSIS OF CONSTRUCTION STATUS OF NAVIGABLE GATEWAY № 3 OF NOVINKINSKY HYDROELECTRIC COMPLEX
The main results of investigations of the state of the navigable lock No. 3 of the Novinkinsky hydrounit of the FBU«Administration «Volgo-Balt» are presented. The analysis of design, construction and operational documentation, field measurements and observations, results of previous surveys was carried out. The evaluation of the filtration regime in the base and backfill soils was carried out; the asymmetry of the depression curves was recorded on the left and right sides of the chamber. Sediments and horizontal movements of the gateway structures, their mutual displacement, are estimated. It was noted that the largest movement, both in the vertical and horizontal directions, was subjected to the camera section № 13 and the lower head of the lock. The presence of a crack in the concrete massif of the left base of the lower head of the lock is fixed. The dynamics of the development of the crack from the moment of its detection to the present time has been analyzed. The processes of soil removal into the chamber during its filling and emptying through the destroyed axial key in the bottom near section № 13 are described. It was noted that the measures for carburizing the base of the chamber with the aim of stopping the removal of soil into the interior of the cell to date have not led to a positive result. The possible causes of super-project movements of Section № 13 and the lower head of the lock are discussed, as well as the appearance and development of a crack in the bottom of the lower head. Such reasons could be the numerous subsidence of the soil on the site of the hydrosystem, caused, apparently, by a change in the process of exploiting the characteristics of the soil of the base-these are weak sandy soils in which decompensation may develop during the development of suffusion processes. Another possible reason is the poor quality of the works at the construction stage of the lock: poor performance of works on backfilling (failure to fill the layer seal, use of non-design soils), as well as poor quality of concrete caused by the use of local soil as a filler and a violation of concreting technology. Recommendations are given on the directions of further studies of the state of the structures of the hydrounit