Risk Analysis And Maintenance Strategy Study Of Earth-rock Dam Based On Reliability

The earth-rock dam is a kind of dam which is used earlier and more widespread. It plays an important role in solving floods, drought and water shortage, developing national economy and protecting the people's life. However, the majority of exiting earth-rock dams was built in the 1950s and 1960s, left many potential safety problems due to lack of experience and unscientific construction methods. After several decades of operation, part of them has entered the old stage and problems exiting in design and construction have gradually exposed. In addition, operational guidance cannot follow, causing many dangerous reservoir. The overtopping number of earth-rock dam is largest and the overtopping rate is highest. The proportion of earth-rock dam in dam crash accidents reaches 70.5%. Once the dam crashes, immeasurable losses will be caused to the country and people's life and property safety. Based on the above reasons, the dam safety has been receiving the domestic and foreign universal attention.Generally the dam safety identification is based on engineering data, test results and field sampling-site inspection. The identification results did not consider the uncertainty of various factors affecting the dam. In fact, the safety and reliability of earth dam design and operation depends on its ability to bear external load. But the load and resistance functioned on earth-rock dam are stochastic quantity, leading to crash risk. This uncertainty can be better considered using risk analysis theory. We can use probability theory to calculate the dam accident risk for safety evaluation.The risk analysis is an effective tool to evaluate and improve the safety of the embankment dam. It can study the dam weakness or deficiencies combining engineering judgment, improve awareness of crash reason and the consequences of dam overtopping and provide scientific basis to decision-making.In this paper, the author used risk analysis based on reliability to study the dam risk. Taking the Heihushan dam reservoir as research background, landslides and floods overtopping were selected as the main failure models and the reliability of Heihushan dam was analyzed.Method of determining the optimal inspection interval for earth dam was explored. Firstly the author studied method of determining the optimal inspection interval for degenerated system, and then took earth-rock dam as degenerated system and made the maintenance strategy with the least-cost as object function during the lifetime so as to determine earth dam maintenance time.Determining the key maintenance place. Based on the finite element thought, the author worked out computer program using Matlab and obtained the stress field distribution of earth dam. Taking the biggest shearing stress theory as control criterion, the key maintenance place was determined. And then suitable engineering measures were adopted to solve the existing crack and stable problem.