Experimental study of the effect of fracture size on closure behavior of a tensile fracture under normal stress
Experimental study of the effect of fracture size on closure behavior of a tensile fracture under normal stress
复制标题
DOI：
10.1016/j.ijrmms.2008.11.008
复制
发表时间：
2009-04
影响因子：
7.2
通讯作者：
A. Giwelli;K. Sakaguchi;K. Matsuki
中科院分区：
文献类型：
--
作者：
A. Giwelli;K. Sakaguchi;K. Matsuki
在垂直于层面的砂岩中用钢楔产生37.5mm×37.5mm ~ 260 mm × 260 mm的拉伸裂缝，并在实验室中测量了这些裂缝在高达10 MPa的正应力下的闭合情况，以研究裂缝尺寸对闭合行为的影响。在测试之前，通过使用具有激光轮廓仪的非接触式表面轮廓测量系统测量上表面和下表面的形貌来确定孔径分布，并且通过使用标准快速傅里叶变换（FFT）来计算初始孔径和表面高度的功率谱密度（PSD）。实验结果表明，在给定的正应力下，闭合度随裂缝尺寸的增大而显著增大。然而，正应力和闭合之间的关系，归一化的标准偏差（SD）的初始孔径，几乎是独立的裂缝尺寸，因为SD的初始孔径也随着裂缝尺寸的增加。因此，在正常应力下裂缝闭合的尺寸效应取决于初始孔径的SD。
Tensile fractures that measured from 37.5mm×37.5mm to 260mm×260mm were created in sandstone perpendicular to the bedding plane by intending steel wedges, and closure of these fractures under normal stresses of up to 10MPa was measured in the laboratory to investigate the effect of fracture size on closure behavior. Prior to the tests, the aperture distributions were determined by measuring the topography of the upper and lower surfaces using a non-contact surface profile measurement system with a laser profilometer, and the power spectral densities (PSDs) of the initial aperture and the surface heights were calculated by using a standard fast Fourier transform (FFT). The experimental results showed that at a given normal stress, closure significantly increases with an increase in fracture size. However, the relation between normal stress and closure, normalized by the standard deviation (SD) of the initial aperture, is almost independent of the fracture size, since the SD of the initial aperture also increases with fracture size. Thus, the size effect on the closure of a fracture under normal stress is governed by that on the SD of the initial aperture.