Monitoring Data Back Analysis and Safety Evaluation of the Second Channel Discharge Sluice, Gezhouba Project, on the Yangtze River

摘要

The Yangtze River is the longest river in China and the Gezhouba Key Water Control Project is the first large scale key water control project on the Yangtze River which has produced great economic and social benefits. Therefore, the safety and stability of the Gezhouba dam during operation after its construction are of great importance. A-mong the structures of the principal parts, the Second Channel Discharge Sluice is a vital one. On the one hand, the sluice is very important because it undertakes the main tasks of flood discharge, sand ejection, navigation control and water level control for electricity production; on the other hand, it is confronted with a number of difficulties because it is based on weak bed rocks, has multiple sluice ways, discharges water pereninially, its chamber floor and apron are immersed in deep water which complicates their maintenance, etc. For these reasons, to analyse the Second Channel Discharge Sluice is of representative significance. On the basis of safety monitoring of this sluice, this paper presents the results of analysis concerning its safety and stability. Firstly, the monitoring data accumulated for many years were back analysed and the various physical parameters characterizing the current state of operation of the structure were obtained; secondly, the operation behaviors of structure and its foundation under various possible operation states were numerically simulated in detail by the 3-D FEM and the deterministic model of key effect quantities at key locations was constructed and standards for safety monitoring were worked out to monitor and control the operation of the structure in the future ; and finally, the safety of structure was evaluated by the safety factor method and thereby the conclusion that the Second Channel Discharge Sluice is in a safe state of operation was drawn.