The Replacement Measures and Study of Reinforcing Effects of the Coal Mined-out Area of Dukouba Dam Abutment

The coal mined out area in sandstone is an outstanding problem for Dukouba arch dam's abutment stability.To determine the concrete replacement depth of coal mined-out area in the abutment,this paper conducted numerical simulation by employing finite element method,and compared in detail the dam and deformation characteristics of Dujouba dam under operation condition of original foundation and the three reinforcement conditions,whose concrete replacement depths of coal mined out area are separately 50m,80m and 100m during normal storage period.The comparison shows that the dam stress and deformation are strongly affected by the coal mined out area in abutment,reinforcement measures must be taken.Compared with the original foundation conditions,when the replacement depth reaches 80m,the distribution of dam stress and deformation have been significantly improved,the tensile stresses on upstream dam surface are decreased remarkably.The overload bearing capacity of the dam and foundation are increased to meet the design requirements.