Figure 3. (a)
The relationship between the
contact temperature of the contact surface and friction coefficient of
the loess. (b) The relationship between the contact temperature of the
contact surface and friction coefficient of the fault geomaterial. (c)
The relationship between the ambient temperature and friction
coefficient of the loess under different sliding velocities. (d) The
relationship between the ambient temperature and friction coefficient of
the fault geomaterial under different sliding velocities.
4.2 Strengthening and
weakening effects of friction
Before the contact temperature reaches the phase transition temperature,
the friction coefficient will show different trends with the increase of
sliding velocity, i.e., gradually decreasing (weakening effect),
basically unchanged, and progressively increasing (strengthening
effect). This is since the difference between the creep activation
energy in the normal and tangential directions of the geomaterial.
This difference indicates the relative ease with which creep occurs in
the normal and tangential directions. When the difference between the
activation energy of tangential and normal creep is small, the friction
coefficient is a very slight change with the slow increase of the
sliding velocity. This means that the tangential and normal creep
processes are similar in difficulty, resulting in almost constant
friction coefficient, as shown in Figure 4.