Experimental Study On The Strength And Deformation Of Dam Concerete Under Biaxial Stress

Nowadays, although there are some research materials about the failure criterions and constitutive models for hydraulic mass concrete all over the world, most of them focus mainly on the uniaxial stress state, when it comes to multiaxial stress state, experimental research and literatures are rare at present. In addition, whether or not the existing failure criterions are suitable for use in hydraulic mass concrete remains questionable.The above-mentioned circumstance is unfavorable for the design of gravity dams. Combined with the actual project(Xiluodu Dam project),this paper has carried out systemic experiments on strength and deformation characteristics of wet-screend concrete cubic specimens under biaxial stress states and obtained some relative results, including failure condition, damage mechanism,peak stress,peak strain and constitutive relationship curves. Based on the experimental results, this paper develops an appropriate failure criterion model and a suitable constitutive model for the concrete of wet-screened second gradation. Comparison between the proposed model and the experimental results indicates good agreement. The major contributions of work are summarized as follows:1A new test method for evaluating the tensile strength in multiaxial compression-tension is developed. This method adopts a glued double-plated manner combined with a plastic brush. Lots of experiment results in this paper have demonstrated that this method can reduce the restraint effect caused by adhesive force between concrete and the glued plate to the compression defomation of specimens under multiaxial compression-tension stress states. It is a reasonable multiaxial compression-tension method characterized by its convenience,uniform stress distribution, enough validity and higher stability.2Tests on uniaxial compression and tension of wet-screened second grade concrete are carried out respectively. The uniaxial compression constitutive model proposed by Saenz has been used to simulate the experiment data. The fitting model coincides well with experimental data.Meanwhile, the simple straight line model is properly used to simulate the rising step of the tension stress strain relationship.3The strength and deformation of wet-screened two grade concrete under biaxial tension-tension, compression-tension and compression-compression stress state is studied systemically. Ultimate strength envelope graph of concrete under biaxial stress state is obtained by means of regressive analysis on test data. The nonlinear elastic total constitutive model and the nonlinear elastic incremental model have been used to simulate the biaxial stress-strain relationship and both of them could well describe the experimental curves. The calculated results have good accuracy which are suitable in analysis of practical engineering.