MODELING OF ROCK FRICTION .1. EXPERIMENTAL RESULTS AND CONSTITUTIVE EQUATIONS
MODELING OF ROCK FRICTION .1. EXPERIMENTAL RESULTS AND CONSTITUTIVE EQUATIONS
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DOI：
10.1029/jb084ib05p02161
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发表时间：
1979-01-01
影响因子：
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通讯作者：
DIETERICH, JH
中科院分区：
文献类型：
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作者：
DIETERICH, JH
在加利福尼亚州雷蒙德的花岗闪长岩地面上进行的直接剪切实验，在约 6 MPa 的法向应力下，证明了竞争时间、位移和速度效应控制着岩石摩擦。提出滑动表面之间的接触点数量的强度决定了摩擦强度，并且接触数量随着位移而连续变化。先前的实验表明，触点的强度随着触点的使用年限而增加。目前的实验表明，需要与表面粗糙度成正比的特征位移来改变接触的数量。因此，在滑动过程中，接触点的平均寿命以及摩擦强度随着滑动速度的增加而降低。只要位移减少了触点的平均寿命，位移就会减弱，从而可能出现不稳定滑动。除了由位移依赖性和时间依赖性引起的速度依赖性之外，实验还表明，每当滑移速度增加时，摩擦力会出现竞争性但短暂的增加。还观察到滑动表面在低于稳态滑动应力的情况下发生蠕变。开发的本构关系允许对作为表面粗糙度函数以及不同时间和速度历史的摩擦与位移数据进行定量模拟。实验中的不稳定滑移是由这些本构效应和实验系统的刚度控制的。有人认为类似的特性控制着地震的不稳定性。
Direct shear experiments on ground surfaces of a granodiorite from Raymond, California, at normal stresses of ∼6 MPa demonstrate that competing time, displacement, and velocity effects control rock friction. It is proposed that the strength of the population of points of contacts between sliding surfaces determines frictional strength and that the population of contacts changes continuously with displacements. Previous experiments demonstrate that the strength of the contacts increases with the age of the contacts. The present experiments establish that a characteristic displacement, proportional to surface roughness, is required to change the population of contacts. Hence during slip the average age of the points of contact and therefore frictional strength decrease as slip velocity increases. Displacement weakening and consequently the potential for unstable slip occur whenever displacement reduces the average age of the contacts. In addition to this velocity dependency, which arises from displacement dependency and time dependency, the experiments also show a competing but transient increase in friction whenever slip velocity increases. Creep of the sliding surface at stresses below that for steady state slip is also observed. Constitutive relationships are developed that permit quantitative simulation of the friction versus displacement data as a function of surface roughness and for different time and velocity histories. Unstable slip in experiments is controlled by these constitutive effects and by the stiffness of the experimental system. It is argued that analogous properties control earthquake instability.