Measurement And Analysis Of Mechanical Behavior Of The Meso-structure Of Concrete

To obtain the material mechanical properties, constitutive relation and failure regularity on concrete mesoscopic component including aggregate, mortar and adhesive layer, the concrete’s mechanical properties are measured and its mechanical behavior is studied on mesoscopic level through test and numerical analysis in this paper. It has a significant influence on the deep understanding of failure mechanism, the improvement of material properties, the guidance of material enhanced design, the development of new material and energy saving.Through the analysis of tensile and compression test of nonporous bluestone, the results including yield load, ultimate load, displacement, stress, strain and elastic modulus are obtained, at the same time, the tensile test data of drilling bluestone by drilling loading method compares with tensile test data of nonporous bluestone, which shows that the real ultimate stress of the rock can be reflected by drilling loading method correctly. The curves of yield load, ultimate load, displacement, stress, strain and elastic modulus are obtained under tensile and compression conditions respectively, through uniaxial compression test of nonporous mortar and uniaxial tensile test of drilling mortar by drilling loading method.The finite element model of bluestone is established and the influence of elastic modulus and poison’s ratio on stress and strain is analyzed, analysis result shows that elastic modulus has a weak influence on axial stress, and the influence on axial strain and principal stress is significant. However, poison’s ratio has a weak influence on axial stress and principal stress, but the little poison’s ratio, the larger axial strain and principal strain. Through the analysis of load mode of action on stress and strain including concentrated load, distributed load and uniform load, the appearance of similar extreme stress between conditions that under concentrated load and under distributed load is discovered, which proves the feasibility of measurement concentrated load mode on measuring the tensile stress of rock, and the extreme stress under uniform load is a quarter of the extreme stress under concentrated load. The function curve between stress concentration factor on the model hole edge and diameter aspect ratio can be established and fitted respectively by the analysis result of finite element model. It shows that peripheral stress faraway from dangerous interface is small and both the rule perforated rectangular and irregular drilling specimen are all effective.Under unidirectional uniform load, the inflection point of strain and displacement on interface indicates that material of bonding interface is different from mortar and aggregate by the numerical analysis of concrete aeromonas homogeneous mesoscopic model under uniaxial compression condition. The rapid changed stress also shows that this interface is weak and dangerous. The media surrounded the interface influences the distribution of displacement and stress, the stress changes rapidly as the proportion of mortar changes and it predicts that the change of stress trend slows down when the proportion of mortar transits slowly. The stress of bonding interface is minimum and the stress concentration appears at the corner of bonding interface, which shows that the aggregate forming arc irregularities will weaken the stress concentration.