Hydraulic characteristics of rough fractures in linear flow under normal and shear load
Hydraulic characteristics of rough fractures in linear flow under normal and shear load
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DOI：
10.1007/s00603-002-0028-y
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发表时间：
2002-10-01
影响因子：
6.2
通讯作者：
Cho, TF
中科院分区：
文献类型：
--
作者：
Lee, HS;Cho, TF
建立了一套能同时测量裂隙流量、法向位移和剪切位移的水力-力学试验系统，用于研究粗糙拉伸裂隙的水力特性。在各种正常和剪切载荷下使用分裂器人工产生的粗糙岩石裂缝上进行了线性流动的实验室水力试验。在测试之前，通过使用激光轮廓仪测量上部和下部断裂表面的形貌来确定孔径分布。初始孔径分布的实验变差函数被分为四组地质统计模型，虽然整体实验变差函数可以很好地拟合指数模型。当正应力增加到5 MPa时，粗糙岩石裂隙的渗透率随正应力的增加呈指数衰减。在单调剪切加载过程中的水力行为显着影响的膨胀发生，直到剪切应力达到峰值强度。随着膨胀程度的增加，粗糙断口试样的渗透率增加更多。然而，超过约7至8毫米的剪切位移，渗透率逐渐达到最大阈值。凹凸体退化和断层泥产生的综合影响阻碍了平均裂缝孔径的随后扩大，是导致这种现象的主要原因。循环剪切加载过程中的渗透率变化表现出一些不规则的变化，特别是在第一个剪切加载周期后，由于粗糙度退化和生产的凿孔材料的复杂的相互作用。分析了水力孔径与机械孔径之间的关系，探讨了三次定律适用的机械孔径范围。
A hydro-mechanical testing system, which is capable of measuring both the flow rates and the normal and shear displacement of a rock fracture, was built to investigate the hydraulic behaviour of rough tension fractures. Laboratory hydraulic tests in linear flow were conducted on rough rock fractures, artificially created using a splitter under various normal and shear loading. Prior to the tests, aperture distributions were determined by measuring the topography of upper and lower fracture surfaces using a laser profilometer. Experimental variograms of the initial aperture distributions were classified into four groups of geostatistical model, though the overall experimental variograms could be well fitted to the exponential model. The permeability of the rough rock fractures decayed exponentially with respect to the normal stress increase up to 5 MPa. Hydraulic behaviours during monotonic shear loading were significantly affected by the dilation occurring until the shear stress reached the peak strength. With the further dilation, the permeability of the rough fracture specimens increased more. However, beyond shear displacement of about 7 to 8 mm, permeability gradually reached a maximum threshold value. The combined effects of both asperity degradation and gouge production, which prohibited the subsequent enlargement of mean fracture aperture, mainly caused this phenomenon. Permeability changes during cyclic shear loading showed somewhat irregular variations, especially after the first shear loading cycle, due to the complex interaction from asperity degradations and production of gouge materials. The relation between hydraulic and mechanical apertures was analyzed to investigate the valid range of mechanical apertures to be applied to the cubic law.