Stress And Stability Analyses Of Compound RFC-CSG Dam

Ordinary gravity dams have been booming with the rapid development of the concrete construction technology, the construction machinery and the related theory. In recent years, some new types of dams, such as cemented sand and gravel (CSG) dam and rock-fill concrete (RFC) dam are proposed.This paper proposes a new idea that uniting RFC material and CSG material to build dams. RFC material is used in the upstream side. So that, seepage control measures at the upstream face of CSG dam can be eliminated; the dam size can be reduced and the construction speed can be accelerated. CSG material is used in the downstream side,which may fully utilize the material strength. More importantly, the large size rocks in the excavated riverbed sand and gravel can be used to make RFC marerial, and the rest can be used to make CSG material. Thus the local material can be fully used and the negative impact on the environment can be reduced.Taking a gravity dam as an example, this paper carries out preliminary study on the behavior of compound RFC-CSG dams. First, by using material mechanics method, the effect of the upstream face slope and the interface slope between two materials on the stress and stability of the dam is analyzed. And some dams that the stability and strength fit the requirements are given. Then, the stability of the RFC part is analyzed by taking the CSG part as granular and RFC part as retaining wall. Finally, the sensitivity analysis on the interface of the dam and the bedrock and the interface of two materials is implemented by using nonlinear finite element method. The following clusions are drawn:(1) When upstream and downstream slopes of the compound material dam are fixed, the dam stability decreases monotonically with the increase of the interface slope. But the dam stress is not change monotonically with the change of the interface slope. There is a turning point. In order to reduce the dam size, save construction costs, appropriate interface slope should be selected by taking stability and strength requirements into account. (2) When the upstream face of the compound material dam is tilted slightly to the upstream, the dam stability increases. But the dam stress reduces, so that it is not conducive to meet the code requirements.(3)To ensure the safety of dam, the stability of the RFC part should be analyzed by taking the CSG part as granular and RFC part as retaining wall along with the design of compound material dam.(4)The dam and bedrock interface, especially dam heel, dam toe, and the transition zone of the interface of two materials prone to yield. So, special attention should be paid to these parts.