A Study on Microscopic Deformation Behavior of Rocks under Compression

岩石受压微观变形行为研究

基本信息

批准号：
07455405
负责人：
ISHIJIMA Yoji
金额：
$ 5.06万
依托单位：
HOKKAIDO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1997
项目状态：
已结题

项目摘要

Uniaxial compression tests and triaxial compression tests under confining pressure of 5 MPa were carried out on cylindrical specimens of lnada granite, whose axis coincided with rift or grain plane. Load was removed when circumferential strain reached certain values. P-wave velocity of loaded specimens in axial and radial directions was measured. Replicas of sections, whose normal coincided with loading axis, were observed undera microscope.P-wave velocity in the axial direction for specimens were larger than that for unloaded specimens in uniaxial case. On the other hand, that decresed slightly with triaxial loading. P-wave velocity in the radial directions decreased in the both uniaxial and triaxial cases. That in R-and G-direction was small than that in H-direction. P-wave velocity in the uniaxial case was smaller than that in the triaxial case with reference to circumferential strain value at unloading. They showed similar behaviors with reference to permanent circumferential strain value.The thin section method with a blue resin and the replica method were used in order to observe cracks. Determination of mineral type with the replica method was difficult. However, preparation of replica is easy and the method enables observation of cracks in opaque minerals.Crack density was evaluated with the scan-line method. The crack density increased with circumferential strain magnitude at unloading. That in triaxial casa was smaller than that in uniaxial case with reference to circumferential strain value at unloading. On the other hand, they showed similar behaviors with reference to permanent circumferential strain. In the uniaxial case, cracks that oriented to rift or grain plane dominated. Crack directivity was not observed in the triaxial case. P-wave velocity decreased with crack density. Rate of the decrease in the triaxial case was larger than that in the uniaxial case. Effects of measuring direction (wave path and scan line) was not observed.

对轴线与裂谷或粒面重合的lnada花岗岩圆柱形试件进行了5 MPa围压下的单轴压缩试验和三轴压缩试验。当周向应变达到一定值时去除负载。测量了加载样本在轴向和径向上的纵波速度。在显微镜下观察法线与加载轴重合的切片复制品。单轴情况下，试件轴向纵波速度大于未加载试件。另一方面，随着三轴载荷的增加，该值略有下降。在单轴和三轴情况下，径向 P 波速度均降低。 R方向和G方向的值比H方向的值小。参考卸载时的周向应变值，单轴情况下的纵波速度小于三轴情况下的纵波速度。它们在永久周向应变值方面表现出相似的行为。使用蓝色树脂薄片法和复制法来观察裂纹。用复制法测定矿物类型很困难。然而，复制品的制备很容易，并且该方法可以观察不透明矿物中的裂纹。裂纹密度采用扫描线法进行评估。裂纹密度随着卸载时周向应变大小的增加而增加。参考卸载时的周向应变值，三轴情况下的值小于单轴情况下的值。另一方面，它们在永久圆周应变方面表现出类似的行为。在单轴情况下，以裂谷或晶面取向的裂纹占主导地位。在三轴情况下没有观察到裂纹方向性。纵波速度随着裂纹密度的增加而降低。三轴情况下的下降率大于单轴情况下的下降率。没有观察到测量方向（波路和扫描线）的影响。