Experimental Study On Dynamic Biaxial Compression Test And Damage Constitutive Model Of Full-graded Concrete

In the actual engineering,most of the hydraulic structures such as gravity dams and arch dams all adopt three-graded or full-graded concrete.The hydraulic structures are generally working under biaxial or triaxial stress state during the period of use.And the concrete is a rate sensitive material,it is unavoidable subjected to dynamic loading in practical application.So it is very important to develop the mechanical properties of full-graded concrete under dynamic loading.And the researchers around the would have gradually turned the study of the static mechanical properties of concrete into dynamics,and extended to the study of concrete damage gradually.Therefore,based on the above reasons,the ultimate strength,deformation,stress-strain relationship of full-graded concrete under dynamic biaxial compression were studied in this paper,and the damage constitutive model under dynamic biaxial compression with damage theory was proposed.The dynamic biaxial compression test of full-graded concrete was carried out under the stress ratio of 1:0,1:0.25,1:0.5,1:0.75.1:0,and the strain rate of 10-5/s,10-4/s,10-3/s,10-2/s was studied.The specific researching contents and conclusions are summarized as follows:(1)A dynamic biaxial compression test was carried out on full-graded concrete.The failure modes,ultimate compressive strength,elastic modulus and stress-strain curves of the specimens were analyzed.The strength failure criteria was established in the principal stress space and octahedral stress space respectively.The relationship between ultimate strength of full-graded concrete and strain rate and stress ratio was analyzed.(2)Combined with different types of concrete test data of other researchers,comparative analysis was made between the full-graded concrete and the normal concrete,the saturated aggregate concrete and the wet screened concrete on the same testing machine.The results show that different types of concrete exhibit cracks at 0°-40° with different main stress directions,and the ultimate strength of different types of concrete shows a direct proportional relationship with the strain rate.The stress-strain curves of different types of concrete have a general trend.The strength criterion relationship can better reflect the strength relationship betweendifferentconcretesandfull-gradedconcrete.(3)The dynamic damage factor and static constitutive model were combined to establish the dynamic damage constitutive model for concrete.The dynamic characteristics and damage models of concrete under different load types were studied.The results show that the damage constitutive model can well reflect the stress-strain relationship of full-graded concrete.