Analysis on the impact of the status of the fresh-old concrete bonding interface on dam safety

The bonding problem of interface between the fresh and old concrete is one of the main technological difficulties in the Heightening Project of Danjiangkou Dam in the South-to-North Water Diversion Project. At present, no mature experiences or engineering examples are found in China for concrete dam heightening. Because of the external environmental impacts of temperature change, aging and hydraulic fracturing on the interface between the fresh and old concrete, crack is likely to occur, which brings risks to the safe operation of the dam. In this article, the finite element direct force method was used to calculate the internal force. The safety of No. 1 dam monolith was calculated in accordance with the standard method for gravity dam in three conditions of fresh-old concrete bonding interface, i.e., perfect condition, cracked interface and cracked interface with water seepage. Suggestions for their solutions were also provided.