The nanoscale elastic moduli and hardness of the constituent minerals of the Class II Kuru granite and the Class I Fauske marble were experimentally investigated. The aims were to correlate the microcrack patterns with the nanomechanical properties of the minerals, and to help understand the important roles of the nanomechanical properties of the minerals in brittle and ductile behaviors. Cylindrical rock specimens were uniaxially loaded to various stress levels in both the pre- and post-peak stages. The specimens were then unloaded to zero, and two thin sections –– one parallel with and the other perpendicular to the loading direction –– were prepared from each specimen. Nano-indentation tests were conducted on the thin sections to measure the elastic moduli and hardness of the major constituent minerals in the rocks. The test results showed that both the elastic moduli and hardness of the minerals abruptly decreased when the applied stress was above 80 % of the uniaxial compressive strength of the rock in the pre-peak stage and also in the entire post-peak stage. At the same time, the values of the two properties became more scattered with increasing damage to the minerals. The number of intragranular cracks was significantly less in the harder quartz and microcline than in the softer calcite. The abundant intragranular cracks in the calcite dissipated most of the strain energy in the Class I marble, such that the rock was not burstable after failure. A small number of intragranular cracks were created in the quartz and microcline in the Class II granite, such that most of the strain energy in the minerals was released to eject rock after failure. Intragranular cracking is thus a key factor in determining whether a rock is burst-prone or not.

中文翻译：

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延展性 Fauske 大理岩和脆性 kuru 花岗岩中组成矿物在进行性破坏过程中的纳米力学性能变化


实验研究了 II 类 Kuru 花岗岩和 I 类 Fauske 大理岩的组成矿物的纳米级弹性模量和硬度。目的是将微裂纹图案与矿物的纳米力学性能相关联，并帮助理解矿物的纳米力学性能在脆性和延展性行为中的重要作用。圆柱形岩石试样在峰前和峰后阶段均受到不同应力水平的单轴载荷。然后将试样卸载到零，并从每个试样制备两个薄片 - 一个平行于加载方向，另一个垂直于加载方向。对薄片进行了纳米压痕测试，以测量岩石中主要组成矿物的弹性模量和硬度。试验结果表明，在峰前阶段和整个峰后阶段，当施加的应力超过岩石单轴抗压强度的 80 % 时，矿物的弹性模量和硬度均急剧下降。同时，随着矿物损伤的增加，这两种特性的价值变得更加分散。较硬的石英和微斜面的晶内裂纹数量显著少于较软的方解石。方解石中丰富的晶内裂纹耗散了 I 类大理岩中的大部分应变能，使岩石在破坏后不会爆裂。II 类花岗岩中的石英和微斜长岩中产生了少量晶内裂纹，因此矿物中的大部分应变能在破坏后被释放出来以喷射岩石。因此，晶内开裂是决定岩石是否容易爆裂的关键因素。