基于数字散斑技术的垂直裂缝扩展实验  

Experiments of vertical fracture propagation based on the digital speckle technology

作　　者：刘合[1] 王素玲[2] 姜民政[2] 张一鸣[2] 

机构地区：[1]中国石油勘探开发研究院 [2]东北石油大学机械科学与工程学院

出　　处：《石油勘探与开发》2013年第4期486-491,共6页Petroleum Exploration and Development

基　　金：国家自然科学基金(51004023)

摘　　要：利用砂/泥岩相似材料进行垂直裂缝扩展实验,采用数字散斑相关技术分析加载过程试样中应力应变场,以分析垂直裂缝的扩展特性。实验结果表明:在界面层强度较高时,裂缝从低强度材料一侧扩展比从高强度一侧扩展更易发生偏转,当界面粘接强度较弱时,无论裂缝从高强度材料一侧还是从低强度材料一侧扩展,经过界面时,均极易发生界面脱胶,导致裂缝经界面后错动传播;裂缝穿过界面前,扩展路径越长,经过界面后越易发生偏转;预制裂缝越短,裂缝经界面时越易发生偏转。引起裂缝偏转的主要原因在于层状介质间材料的力学性能差异,其导致界面层处产生了剪切应变,剪切应变可诱导Ⅱ型剪切裂缝的产生,致使裂缝扩展转向,界面处产生的剪切变形越大,裂缝偏转的角度越大。The vertical crack propagation behavior for sandstone/mudstone layered specimen made by the similar material was analyzed. The stress and strain field was obtained using Digital Speckle Correlation Method to analyze the propagation characteristics of vertical cracks. The test shows that the higher the strength of the interface layer, the more susceptible the crack deflects from the side of the low-strength than from the side of the high-strength of the material. It is easy for the interface to unglne when the interracial adhesion strength is weak, which results in the dislocation propagation after the crack passing the interface. The longer the growth path is before the crack passing the interface, the more likely it deflects after passing the interface. Similarly, the shorter the initial prefabricated crack is, the more susceptible it deflects after the crack passing the interface. The main factor of the deflection is the difference in the properties of the composite materials, resulting in a larger shear strain of the interracial layer. The shear strain can induce type Ⅱ shear fracture, so it is the main factor leading to crack deflection. The bigger the shear deformation is, the more intensive the crack deflection is.

关 键 词：垂直裂缝 砂 泥岩界面 裂缝扩展 裂缝转向 数字散斑实验 

分 类 号：TE357.1[石油与天然气工程—油气田开发工程]