Experimental And Theoretical Study On The Static And Dynamic Mechanical Properties Of Dry And Saturated Concrete

Concrete is a typical heterogeneous brittle material, widely used in the national economic construction and national defense construction.The study on mechanical properties of concrete under the action of water, has a very significant value and significance, in project underground and underwater engineering etc. Based on the experiment about quasi static and dynamic mechanical properties of dry and saturated concrete, damage evolution equations of concrete are established, and the concrete constitutive model with damage is carried out,which is the main research topic of this thesis.The study focuses on the different confining pressure triaxial compression tests and uniaxial compression tests on dry and saturated concrete.And SHPB experiments were taken on dry and saturated concrete by split Hopkinson bar device. According to the test data,the stress-strain curve, relationship between strain at peak stress and confining pressure, strength and deformation properties are analyzed,to acquire the static and dynamic mechanical characteristics and rules of dry and saturated concrete under different confining pressure and different strain rate. In same confining pressure, saturated concrete compressive strength is lower, the peak strain larger.The nonlinear curves of dry and saturated concrete are different. The dry and saturated concrete has obvious strain rate effect. The stress-strain curve representing ascending under moderate strain rate is steeper than quasi-static curve. The increased amplitude of dynamic strength of saturated concrete, which have a stronger sensitivity about strain rate, is nearly twice of that of dry concrete. There is a threshold sr among strain rate. Only when the strain rate is greater than the threshold?., the dynamic strength of saturated concrete is stronger than that of dry concrete. Based on the experimental results, analyzing the influence mechanism, the equation of the relationship between concrete strength and strain rate is given, which may predict the relationship between the strength of the varied saturation concrete and strain rate. Based on the simplified damage evolution equation of single axis by using Hsieh-Ting-Chen four parameter failure criterion, a damage constitutive model with concrete is established, whose parameters are easy to get, and the constitutive relation curve and test curve model under different conditions are basically the same.