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本文对济南辉长岩经历不同应力途径后岩石晶粒内的微破裂特征的观测进行了研究.实验中岩石样品首先承受较高的围压(使应力差达到岩石强度的80%),然后分别按 A,B,C 三种途径进行实验.三种途径已在另一文中作了叙述(见地震学报第2卷第3期237页).实验结束后,将岩石样品切开,制成标准薄片及光片.通过显微镜的观测发现,三种应力途径所引起的微破裂性质明显不同.在 B 型实验中,长石晶粒内的微裂纹表现得短小,其长度多数不超过长石晶粒短轴的长度.整个岩石样品内微裂纹的分布密集于较小的范围内.在 C型实验中,倾斜裂纹数量增多,长石晶粒中的裂纹比 A 和 B 实验更长和更多,出现一种“星”状的微裂纹.观测到的辉长岩的微观现象可能说明与岩石标本“过密”、“超膨胀”现象有关.
In this paper, the study on the characteristics of micro-fractures in the grains of Jinan gabbro subjected to different stress pathways is carried out.In the experiment, the rock samples are first subjected to high confining pressure (the stress difference reaches 80% of the rock strength) The experiments were carried out in three ways: A, B and C. The three approaches were described in another article (see Seismological Survey Vol. 2, No. 3, p. 237). After the experiment, the rock samples were cut and made into a standard The results of microscopic observation show that the micro-cracks caused by the three stress paths are obviously different.In the B type experiment, the micro-cracks in the feldspar grains are short and their length does not exceed that of feldspar The length of the short axis of the grain. The distribution of the micro-cracks in the whole rock sample is densely distributed in a small range. In the C-type experiment, the number of oblique cracks increased and the cracks in the feldspar grains were longer and more than the A and B experiments , A “star” -like microcrack appears.The microscopic observation of gabbro may indicate that it is related to the phenomena of “over-dense” and “super-expansion” of rock specimens.