The frictional and micromechanical effects of grain comminution in fault gouge from distinct element simulations
The frictional and micromechanical effects of grain comminution in fault gouge from distinct element simulations
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断层泥中颗粒粉碎的摩擦和微机械效应来自不同元素模拟
DOI：
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发表时间：
2006
期刊：
影响因子：
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通讯作者：
J. Morgan
中科院分区：
文献类型：
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作者：
Yong;J. Morgan
[1] 天然断层带在断层和剪切过程中经历普遍的颗粒粉碎，导致断层泥特性逐渐变化。我们使用离散元法 (DEM) 模拟石英凿的粉碎过程，以研究颗粒粉碎和相关的颗粒特性动态变化对颗粒剪切带摩擦和微观力学行为的影响。圆形和三角形颗粒由圆形颗粒簇构成，通过一些易断裂的键连接，允许颗粒破裂和粉碎。 DEM 实验是通过在 5 至 100 MPa 的法向应力范围内剪切由不同强度的圆形或三角形颗粒组成的相同颗粒组合来进行的。结果表明，应变破碎主要通过改变晶粒形状和尺寸来改变不同变形机制的分配。颗粒粉碎可能会降低或增加凿痕强度，具体取决于颗粒形状变化的方向和程度。晶粒棱角的增加导致断层泥的摩擦强度显着增加，而晶粒伸长率的增加则导致摩擦强度下降。最终强度是由断裂引起的强度降低与晶粒形状和晶粒尺寸分布变化引起的强度变化之间竞争的结果。我们的模拟还表明，窄粒度凿岩中颗粒粉碎的强度和概率受到形状、强度（例如，由于矿物学）和正应力的影响。
[1] Natural fault zones undergo pervasive grain comminution during faulting and shearing, producing progressive changes in fault gouge properties. We simulate the comminution process of quartz gouge using the distinct element method (DEM) to examine the influences of grain comminution and associated dynamic changes in grain characteristics on the frictional and micromechanical behavior of granular shear zones. Rounded and triangular grains are constructed from clusters of circular particles, connected by some breakable bonds, allowing for grain fracture and comminution. DEM experiments are conducted by shearing identical granular assemblages composed of either rounded or triangular grains of different strengths over a range of normal stresses from 5 to 100 MPa. The results show that grain comminution with strain changes the partitioning of different deformation mechanisms, mainly by changing grain shape and size. Grain comminution may decrease or increase gouge strength, depending on the direction and degree of change in grain shape. Increases in grain angularity lead to significant increases in frictional strength of fault gouges, while increases in grain elongation tend to decrease in frictional strength. The final strength results from the competition between strength reduction by fracturing and strength variation by changes in grain shape and grain size distribution. Our simulations also demonstrate that the intensity and probability of grain comminution in narrow grain size gouges is affected by shape, strength (e.g., due to mineralogy), and normal stress.