Reduction of friction on geological faults by weak-phase smearing
Reduction of friction on geological faults by weak-phase smearing
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DOI：
10.1016/j.jsg.2013.03.008
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发表时间：
2013-06
影响因子：
3.1
通讯作者：
E. Rutter;A. Hackston;E. Yeatman;K. Brodie;J. Mecklenburgh;S. E. May
中科院分区：
文献类型：
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作者：
E. Rutter;A. Hackston;E. Yeatman;K. Brodie;J. Mecklenburgh;S. E. May
大多数常见的地壳岩石类型显示出0.6或更高的摩擦系数，但当应力状态为不利方向时（即，对于给定的正应力，断层面上的分解剪应力较低），某些断层在滑动时一定很弱。低摩擦矿物和高孔隙流体压力的作用，无论是单独或组合，经常被调用来解释这种滑动，但分散的弱相的体积分数往往似乎是存在于断层泥的量太小，产生显着的机械弱化。通过人工断层泥的力学试验和运行产物的显微结构研究，证明了机械涂抹可以大幅度增加滑移面上嵌入的弱相（石墨）的有效面积，且滑移面上弱相面积的扩大遵循线性混合规律。这允许初始分散的弱相的相对小的体积分数具有不成比例的大的效果，只要涂抹集中到狭窄的平面滑移区中或集中到它们的互连网络中。
Most common crustal rock types display friction coefficients of 0.6 or higher, but some faults must be frictionally weak as they slip when the stress state is unfavourably-oriented (i.e. the resolved shear stress is low for a given normal stress across the fault surface). A role for low-friction minerals and high pore fluid pressures, either separately or in combination, is frequently invoked to explain such slip, but volume fractions of dispersed weak phases often seem to be present in fault gouge in amounts too small to produce significant mechanical weakening. By means of mechanical tests on synthetic fault gouge and microstructural study of run products, we show that the effective area of an embedded weak phase (graphite) on a slip plane can be substantially increased by mechanical smearing, and that the enlarged area of the weak phase on the slip plane follows a linear mixing law. This allows a relatively small volume fraction of the initially dispersed weak phase to have a disproportionately large effect, provided the smearing is concentrated into a narrow planar slip zone or into an interconnected network of them.