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岩样为大理岩,进行了围压20MPa、不同轴压的常规三轴压缩试验和核磁共振测试试验,测得大理岩在三轴压缩后的应力-应变曲线、弛豫时间T2谱分布和孔隙度,建立了孔隙度与损伤度之间的函数关系。结果表明,(1)孔隙度和轴压比的拟合函数显示,随着轴压的增加,大理岩孔隙度呈指数增长;轴压比小于70%时,大理岩产生弹性变形,孔隙度增长较小,轴压比处于70%~90%阶段时,大理岩以塑性变形为主,孔隙度明显增大,轴压比大于90%时,大理岩产生强烈扩容,孔隙度成倍增长;(2)大理岩内部裂隙数量和裂纹开度均随着轴压的增大而不断增大;(3)损伤度与孔隙度或轴压比的函数关系表明,随着轴压比的增大,大理岩的损伤度不断增大,相同外荷载产生的有效应力也不断增大。
The rock samples were marble, and the triaxial compression tests and NMR tests of the confining pressure of 20 MPa and different axial pressures were carried out. The stress-strain curves of marble after triaxial compression and T2 distribution of relaxation time and Porosity, established a functional relationship between porosity and damage degree. The results show that: (1) The fitting function of porosity and axial compression ratio shows that the porosity of marble increases exponentially with the increase of axial pressure. When the axial compression ratio is less than 70%, the marble deforms elastically and the porosity increases When the axial compression ratio is in the range of 70% -90%, the plastic deformation of the marble is dominant, and the porosity is obviously increased. When the axial compression ratio is more than 90%, the marble has a strong expansion and the porosity multiplies. ( 2) The number of internal cracks and crack opening in marble both increase with the increase of axial pressure; (3) The relationship between damage degree and porosity or axial pressure ratio shows that with the increase of axial compression ratio, The damage degree of marble increases continuously, and the effective stress generated by the same external load also increases continuously.