Study On Elastic-Plastic Stress And Bearing Capacity Of Longtan RCC Gravity Dam

The purpose of this study is to seek a new rational method for stress computation andbearing capacity analysis, which is a common problem in the design of Longtan RollerCompacted Concrete (RCC) Gravity Dam. According to the up-to-date developments inthe field of modern concrete and rock elastic-plastic mechanics, a study on the stresses andbearing capacity of Longtan RCC gravity dam is conducted through the elastic-plasticincrement theory. As a result, stresses and strength safety coefficient of the dam, itsprogressive failure process and tendency of loss-of-stability type is obtained. The study isfocused on the elastic-plastic constitutive theory formulated in strain space with thesoftening plastic features of the materials considered and the calculation of elastic-plasticfinite elements through increment method. Based on the above outcomes, the stress statusand progressive failure process of the dam are analyzed. This method of analysis can fullyreflect the characteristics of concrete materials and overcome the difficulties inloading/unloading judgment for softening plastic constitutive equation. In addition, itserves as a more convenient approach to study the bearing capacity of the gravity dam dueto the improved theory. In accordance with the blemish, softening, expansion and otheractual characteristics of RCC, the thesis innovatively proposes to introduce suchsystematic approaches into the gravity dam study on its progressive failure progress,failure mechanism, bearing capacity, and safety margin as the stability theory and thesafety margin principle that tends to increase the guaranteed ratio of materials for theshearing strength and the tangential strength. Thus a new method for analyzing andcalculating the stability of the gravity dam is established and a criterion to judge theloss-of-stability of gravity dams provided. Meanwhile, a comparison with the safetymargin method of proportional reduction for the friction coefficient and shear-frictioncoefficients carried out. Through the comparison, it is concluded that the bearing capacityof the gravity dam should be controlled by the outcomes derived from the stability theory.The stability theory can reflect the physical mechanism of loss-of-stability of gravity damresulting from the blemish and softening of RCC materials, and according to it the safetymargin factor at the critical conditions prior to the dam losing stability can be directlyobtained. Therefore, the analysis on the bearing capacity of RCC gravity dam isestablished on a precise mechanics basis. This study completes the theory andmethodology for studying the bearing capacity of gravity dam and also promotes theimprovement of the stress and bearing capacity study level for concrete gravity dams.