Physical Model Test On Seismic Dynamic Response Characteristics Of Counter-tilt Combinational Rock Slopes

China is a quake-prone country and earthquake had caused great losses to the people’s life and property. But an earthquake always triggers large amounts of secondary geological disasters, such as landslides, debris flows, rock falls and etc.,which cause great loss even beyond the direct damage.The Guantan landslide, which is located in the right bank of the Jushui river in Jushui town of Anxian country in Sichuan province, failed in May 12, 2008 after the earthquake and is a typical landslide that reacted to after-earthquake effect. The landslide is happened in counter-tilt rock slope with weak rock base, which forms the boundary of dolomite rocks in the upper part and the mudstone in the lower part. The counter-tilt slope tends to be stable, but such large-scale landslide disaster still happens under the earthquake dynamic effect. So, it is very important to study the seismic dynamic response characteristics of counter-tilt combinational rock slopes.Traditional physical model test of slope(such as centrifuge and shaking table) is expensive, complex operation and not widely used. So, I design a simple physical model test device with steel frame and heavy ball in this paper. Based on the geological conditions, I made a physical model of slope based on the prototype of the Guantan landslide, and researched on its dynamic response characteristics. Moreover, I rebuilt another two different angles of slope physical model based on the former model and discussed the influence of the wave amplitude, frequency and slope angle on dynamic response characteristics of the model. This experiment verifies some conclusion, and has obtaines some new understanding, mainly including:(1) The vertical peak acceleration of the incident wave generated by the heavy ball knocks steel plate is larger than the horizontal one, and the attenuation of vertical acceleration in the model is stronger than the horizontal acceleration. Drop height which has little effect on the frequency is in proportion to the incident wave amplitude, and the material of the ball decides the frequency. The amplitude and frequency of the incident wave generated by the steel ball are greater than sand ball, especially in the horizontal direction. The frequency of the incident wave produced by steel ball was significantly higher than the sand ball.(2) The dynamic response manifested free face amplification to the seismic wave, and with the measuring point closing to the surface, the acceleration amplification coefficient P is larger that means the amplification effect is more significant. Moreover, the amplification effect for the horizontal and vertical acceleration is not much difference.(3) The dynamic response manifested vertical amplification to the seismic wave and with the measuring point closing to the top of the slop, the acceleration amplification coefficient P is larger that means the amplification effect is more significant. Moreover, in the lower part of the slope model, the vertical acceleration amplification effect is stronger than vertical acceleration and in upper part, vertical acceleration amplification effect is more significant.(4) Dynamic response characteristics of the model are affected by the amplitude of the incident wave: in front loading test, amplitude has little effect on the acceleration amplification and distribution; in back loading test, the acceleration amplification coefficient had no obvious regularity with the variation of the amplitude, but the overall acceleration amplification coefficient increases with the increasing of the amplitude. So, the direction of the incident wave has great influence on seismic response of the slope.(5) Dynamic response characteristics of the model are affected by the frequency of the incident wave: in both front loading and back loading test, the frequency of the incident wave has little effect on the numerical value of horizontal acceleration amplification coefficient PX, but it changes the distribution laws; However, for vertical acceleration amplification coefficients PY, the frequency of the incident wave has little effect on the distribution laws, but PY increases with the increasing of frequency.(6) Dynamic response characteristics are different in slope models with different dip angle. But the horizontal acceleration amplification coefficient does not have a obvious rule in three models because of the influence of the distance of measuring point and the vibration source, the change of the sensor position in this experiment.