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Size Effect of a Rock Fracture's Shear Property Estimated by Using a Fractal Model

用分形模型估算岩石裂隙剪切特性的尺寸效应

基本信息

批准号：
13450417
负责人：
MURATA Sumihiko
金额：
$ 0.7万
依托单位：
KYOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2003
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-13450417/
关键词：
rock fracture size effect shear property fractal model interlocking shear test syringe pump JRC

项目摘要

We have proposed a method to estimate the size effect on shear properties of rock fracture using JRC-diagram newly developed by us to estimate the surface roughness of a rock fracture rationally based on a fractal model. In order to confirm the validity of this our method for the JRC evaluation, simple shear testing equipment which consisted of precise syringe pump, hydraulic piston cell, rigid frame and shear box was newly designed and was set up, and shear test was carried out by using it. The specimens for the shear test were prepared artificially by the following way. First, numerical topography data of a fracture surface were created using Brown's method. ' Second, a fracture surface was carved on a modeling wax using a NC modeling machine and a matrix of silicon rubber was made. Finally, fracture specimen of mortal was made by molding. By this way, we succeeded in setting the interlocking asperity size, surface roughness, and material strength at will to any specimen. Three types of the specimen whose interlocking asperity size is 2mm, 4mm, and 6mm and whose size is 30mmx30mm, 60mmx60mm, and 90mmx90mm respectively were prepared. As a result of the shear tests for these specimens, the tendency in which the peak shear strength lowered with the increase in the interlocking asperity size was confirmed. For each specimen, JRC was evaluated by using JRC-diagram and the method presented by Barton et al., and they were compared to the JRC estimated from the experimental results. As the result, it was proven that JRC-diagram gives more correct JRC than Barton's. method. In addition, it was proven from the result of shear test for the specimens of sandstone and granite that JRC-diagram could give correct JRC, if the interlocking asperity size is correctly evaluated.

本文提出了一种基于分形模型的岩石断裂面粗糙度的JRC图尺度效应估计方法。为了验证该方法在JRC评价中的有效性，我们设计并搭建了由精密注射泵、液压活塞单元、刚性框架和剪切箱组成的简易剪切试验装置，并利用该装置进行了剪切试验。首先，使用布朗方法创建断裂表面的数值地形数据。第二步，用数控造型机在造型蜡上雕刻出断裂面，制作出硅橡胶基体。最后，用模压法制成人体骨折标本。通过这种方式，我们成功地设置互锁粗糙度的大小，表面粗糙度，和材料强度将任何标本。制备了三种类型的试样，其互锁粗糙度尺寸分别为2mm、4mm和6mm，尺寸分别为30mm × 30mm、60mm × 60mm和90mm × 90mm。作为对这些试样的剪切试验的结果，确认了峰值剪切强度随着联锁凹凸尺寸的增加而降低的趋势。对于每个样本，通过使用JRC图和巴顿等人提出的方法来评估JRC，并与实验结果估算的JRC进行了比较。结果表明，JRC图比巴顿图给出的JRC更准确。法此外，砂岩和花岗岩的剪切试验结果表明，如果能正确估计联锁微凸体的尺寸，JRC图可以给出正确的JRC。