Abstract: Arch dam is a shell structure in space with complex shape. Large tensile stress would lead to instability or even failure of the arch dam. Engineering experiences show that the maximum principal stress of arch dam often appears at the abutment, and tensile stress in the abutment directly affects the safe operation of dam. In the aim of effectively reducing the tensile stress of arch dam, a concrete backfill measure for the over excavation of bank slope is proposed, and the stress conditions of dam abutment in temperature rise and drop conditions in the presence of backfill are compared with those in the absence of backfill. ANSYS the finite element equivalent stress method was employed to establish the integral finite element models of arch dam subjected to hydrostatic pressure, silt pressure, uplift pressure, gravity, thrust of radial gate and so on. Results indicate that backfill could effectively improve the force situation of abutment and reduce the tensile stress in the abutment. The results offer reference for the design and construction of reducing tensile stress in the abutment of arch dam.

Key words: arch dam, concrete backfill, equivalent stress, tensile stress in abutment, finite element model