Study On Mechanical Properties And Damage Mechanism Of Basalt Fiber High Performance Concrete Based On Meso-mechanics

Basalt fiber is a new kind of environmentally friendly,green and high-performance fiber material.So the research of basalt fiber concrete has practical significance.In recent years,scholars have conducted a lot of researches on BFRC,most of which are macroscopic experimental studies,and few numerical simulation studies on its microscopic scale.For the composite material of basalt fiber concrete,the properties of meso components have a great influence on its mechanical properties and damage and failure mechanism,such as the distribution of meso aggregate,the properties of component materials,and the mechanical properties of interface transition zone.Therefore,in this paper,the elastic modulus and damage and failure mechanism of basalt fiber concrete were numerically simulated at the mesoscopic scale.The contents are as follows:(1)Establish the microscopic homogenization model of BFRC,use m-t theory to predict the elastic modulus of basalt fiber concrete,and establish the microscopic random aggregate model of BFRC to calculate its elastic modulus by mechanical formula.The above two results are compared with the actual experimental results to verify their reliability.It is found that the influence of fiber content,length and BFRC elastic modulus can be ignored.The shape of aggregate has no significant effect on the elastic modulus of BFRC.(2)Perform the insertion step of cohesive force unit in Abaqus with the model of divided units.In aggregate interface transition zone,mortar units,three mesoscopic structure of interfacial transition zone into different Cohesive unit,resulting to simulate the damage process of BFRC and validate the results.(3)Based on the bond crack model,the uniaxial tension and compression performance of BFRC and damage and damage process were studied under the conditions of 18 mm fiber length0%、0.11%、 0.2%、0.3% fiber content and different fiber lengths.The optimal content and length of the fiber are obtained,and the influence of basalt fiber with different content and length on the damage mechanism of concrete is obtained.(4)Based on the bond crack model,the BFRC bending performance and damage and damage process were studied under the conditions of 12 mm fiber length,0%、0.11%、 0.15%、0.2%、0.25% and different fiber lengths.The optimum fiber content and length were determined,and the damage process of three point bending and four point bending of basalt fiber concrete beams was analyzed.