Abstract:

A new model test device for simulating the dynamic response of long and large tunnel crossing active fault is proposed; and a new tunnel seismic test method by changing the vibration characteristics of model box, where the vibration characteristics of model box is decided by changing the parameters of combined spring under device platform bottom, is designed to simulate the dynamic characteristics and failure mechanism of the tunnel crossing seismogenic fault. The new model test device can not only solve the problem of forced vibration in traditional test method, but also can simulate the process of the formation displacement caused by fault dislocation decreasing gradually from the location of seismogenic fault to far end of the model box, and then simulate the longitudinal vibration characteristics from fault section to normal section when long tunnel crosses active fault. The vibration frequency and dislocation displacement of the fault can be changed by changing the stiffness coefficient of single spring and number of spring units, etc. Furthermore, the regression formulas of vibration frequencycombined spring stiffness and dislocation displacementcombined spring stiffness can be obtained. By using the formulas obtained, the different combined spring modes can be obtained; and hence the test conditions of different vibration frequencies and dislocation displacements can be simulated in subsequent experiments.

Key words: large and long tunnel, active fault, seismogenic fault, model test, vibration frequency, dislocation displacement