两种晶粒大理岩的力学性质研究

矿物结构是影响岩石力学特性的根本因素。对晶粒0.5～1 mm细晶微风化大理岩和晶粒0.2～0.5 mm粉晶风化大理岩，进行了超声波测试和单轴、常规三轴压缩试验。粉晶大理岩晶粒尺度较小，滑移界面较多，粘接强度稍有变化就显著影响变形，即单轴压缩强度离散性较小而杨氏模量离散性较大，杨氏模量是细晶大理岩的1/3 左右，而单轴压缩强度仅低20 %。细晶大理岩的杨氏模量与围压无关，粉晶大理岩的杨氏模量随围压而增大，但进入延性变形阶段后两种大理岩的三轴强度完全相同。岩样的剪切破坏角都是随围压增大而减小，最后达到Coulomb准则确定的数值。在较高围压下，试样的承载极限与应力路径、材料强度以及内部的缺陷关系不大。晶粒的摩擦决定了大理岩的强度、变形特性。

A study of mechanical property of two marbles with different crystal sizes

The texture of mineral particle is the key point to the mechanical property of rocks. Two kinds of marbles are uniaxial and triaxial compressed. One is slightly weathered with fine-crystal in size of 0.5mm～1mm, the other is weathered with silt-crystal in size of 0.2mm～0.5mm. The silt-crystal marble has much internal boundary to slip during compressing, so the Young’s modulus willbe changed greatly with the cohesion, and the dispersion of Young’s modulus is greater than that of strength. On the other hand, the fine-particle marble is 3 times in Young’s modulus but only 20% in uniaxial strength more than the silt-particle marble. In pseudo-triaxial compression, the Young’s modulus increases with confining pressure for silt-crystal marble, but it is nearly the same as fine-crystal marble. The triaxial strengths of the two marbles in ductile deformation are closed each other. The angle of shear failure increases with the confining pressure and finally reaches the value from Coulomb criterion The supporting capacity of marble specimen is only related to the confining pressure and no matter with the loading path, material strength and flaws. The internal friction between crystals determines the strength and deformation of marble.