Geomechanical model tests on global stability of an arch dam at Dagangshan

The geomechanical model test is an effective method to study the global stability of arch dams. The geomechanical model test on the arch dam with foundation reinforcement at Dagangshan in the similar scale of 250:1 was conducted. The deformation and strength of jointed rock mass, the discontinuous structural surfaces and the reinforcement measures were simulated through the masonry technique of small blocks. The water load imposed on the dam surface was controlled by the hydraulic jacks. The strains and displacements were collected and saved automatically and effectively with a data acquisition system of high accuracy. The high water pressure method was employed for the overload failure test. The stress and displacement distributions of the scaled dam were obtained and the failure processes of the scaled dam and the abutment were explored. Three factors of the global overload safety K1, K2 and K3, were used to evaluate the global stability of dams. The comparative analysis between the geomechanical model test and the numerical simulation based on the deformation reinforcement theory indicated that the global stability of the arch dam at Dagangshan was relatively high. The weak areas controlling the global stability of the arch dam was located.