| In the early tests of rock friction, two forms of frictional sliding, unstablesliding (stick-slip) and stable sliding (creep-slip), had been observed.Experimental researches showed that rock’s stick-slip phenomenon was muchsimilar to seismogenic process, and then found the two had the samemechanism. Therefore, study on rock’s stick-slip has practical significance infault stability and earthquake nucleation.On the basis of experimental observations of rock friction, Dieterich andRuina empirically developed constitutive laws called rate-and state-dependentfriction laws, which according to the different evolutions on state variables, hastwo versions—the slip law and the slow law. The stick-slip phenomenon ofspring-slider model with single degree of freedom could be accuratelydescribed by using one state variable. In the model, the parameter (a-b) controlsthe sliding stability under small perturbations. If (a-b)>0, the model showsvelocity-harden movement, in which friction strength increases with slip rate;if (a-b)<0, velocity-weaken phenomenon will occur, in which friction strengthand slip rate change in the opposite directions. Considering the model underQuasi-static state and dynamic state respectively, we can obtain the model’sstability condition and its critical value.Seismogenic process along a fault’s interface, simply described as a stable-sliding–stable cycle, is similar to the modle’s stick-slip, and so the stabilitycondition is. In this paper, two main questions, which caused the stick-slipphenomenon and how parameters affected on the stable period, were discussedby numerical simulation on the model.In the last part, Xianshuihe-Xiaojiang fault zone, which is concerned byseismologists due to its frequent seismic activity and strong tectonic movement,was studied on the time distribution of M≥7.0earthquakes and the averagerecurrence interval of characteristic earthquakes in this fault zone. Then,several groups of the model’s parameters were given in order to fit the resultsbelow. |
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