摘要
本文研究了玄武岩纤维增强珊瑚骨料混凝土(BFCAC)的三轴力学性能,分析了玄武岩纤维(BF)和孔结构对BFCAC三轴力学性能的影响,建立了BFCAC的强度准则.结果表明,BFCAC的峰值偏应力和弹性模量随着围压非线性增加,两者的围压效应随BF掺量的增加而增大.围压和BF掺量的增加均提高了BFCAC的临界应变和延性变形,但较大围压作用弱化了BF对珊瑚骨料混凝土延性变形的影响.BFCAC的泊松比随BF掺量和围压增大分别增大和减小.BF和围压提升了BFCAC的体积收缩变形,降低了其体积膨胀变形.围压一方面使BFCAC由劈裂破坏逐渐转变为剪切破坏和挤压塑性流动破坏,另一方面,围压也提高了BF与珊瑚骨料混凝土基体间的粘结性能.BFCAC破坏时,裂缝均贯穿珊瑚骨料,且在较高围压时,珊瑚骨料发生孔隙坍塌.BFCAC的小孔不具有分形特征,中孔和大孔的分形特征较为明显,且其孔结构分形维数随BF掺量的增加而增大.孔结构分形维数与三轴力学性能的关系表明,BFCAC的三轴力学性能不仅受BF本身的影响,也受BF对CAC孔结构的影响.建立了BFCAC的改进非线性M-C强度准则,不仅能够准确计算BFCAC的三轴强度变化规律,而且能够有效体现BF和孔结构特征对BFCAC三轴强度的影响.
Abstract
The triaxial mechanical behaviour of basalt fibre-reinforced coral aggregate concrete(BFCAC)was investigated in this study.The results show that an increase in the confining pressure and basalt fibre(BF)content causes an increase in the ductile deformation of BFCAC.The BF and confining pressure can increase the contraction volume deformation of BFCAC and reduce its expansion volume deformation.The confining pressure effect of the peak deviatoric stress and elastic modulus of BFCAC increases with BF content.The Poisson ratio of BFCAC increases as the BF content increases and decreases as the confining pressure increases.In addition,confining pressure causes BFCAC to transform from splitting failure to shear failure and extrusion plastic flow failure.When BFCAC is damaged,all the cracks penetrate through the coral aggregate.The relationship between the pore structure fractal dimension and the triaxial mechanical properties shows that the triaxial mechanical properties of BFCAC are affected by the BF as well as the BF's effect on the pore structure.Finally,an improved nonlinear M-C strength criterion for BFCAC is established.
基金项目
National Natural Science Foundation of China(52222806)
National Natural Science Foundation of China(52278216)
Natural Science Foundation of Shaanxi Province,China(2019JQ-481)
NETL
NSTL
维普
万方数据