| The high slope shallow slope unloading fracture, weathering is strong, and it plays as a continuum and dielectric property difference, seismic response is complicated. The paper has described the geological structure characteristics of the area of the west slope of Qingchuan Dongshan in detail and analyzed the topographic features and rock mass structure of the slope based on the geological survey and indoor data analysis. According to the seismic monitoring data of the slope of Qingchuan Dongshan and the slope geological structure, seismic response characteristics of the slope influenced by slope height, frequency of excellence, topography, and the influence of the epicenter distance has been analyzed. On the basis of which, an improved DDA program is used to establish the analysis model of the west slope of Dongshan, and the influence factors of slope ground motion are analyzed by numerical simulation method. At the same time, the DDA program is used to analyze the influence of different input wave period, joint and soft interlayer on seismic wave propagation. The following conclusions and understanding are obtained through the analysis:(1) According to the monitoring data of Qingchuan Donghsan, combined with numerical simulation analysis shows that when the elevation is less than a certain value, peak seismic acceleration of the linear slope increases with the elevation, peak horizontal acceleration in the direction perpendicular to the ridge direction is much larger than which along the ridge, and the peak acceleration amplification factor of the vertical ridge can increase up to 3.12 times.(2) When the earthquake wave is affected by the external disturbance and the natural frequency of rock mass is close to the natural frequency, the vibration response of the slope rock mass will increase dramatically. When the epicentral distance is far, the seismic P wave energy attenuation amplitude ratio is smaller than that of S wave, and when it arrived at the monitoring points, the seismic wave horizontal acceleration amplification coefficient is greater than that of vertical direction; when the epicentral distance is near, the S wave energy is higher than the P wave energy, as it arrive at the monitoring point, the seismic wave of vertical acceleration amplification coefficient is greater than that of the horizontal direction.(3) Seismic wave propagation through fault and other weak interlayer, under certain conditions will be a certain degree of amplification. Seismic wave will also be magnified by the terrain, the slope of the prominent position and the thin ridge of the vertical direction of the ridge is often more prone to instability sliding. Acceleration amplification coefficient curve in profile of "T"- shaped slope is often convex, in the turning part of the "T"- shaped slope the acceleration amplification coefficient is small.(4) Through the establishment of the generalized numerical model analysis showed that: when the slope angle, slope height is relatively lower, the acceleration amplification coefficient increases with the height and depth of the level, slope height increased to a certain value, the acceleration amplification coefficient no longer increases with the elevation, but shows a circadian change. When the slope angle increases to a certain value, the acceleration amplification factor of the slope is not increased with the increase of the slope angle too.(5) Slope rock is hard or incoming seismic waves with longer periods, the slope acceleration amplification coefficient is larger; when there is a face of jointed rock mass, rock elastic modulus is greater, joint with elastic wave transmission effect is stronger, reflection is weak; when the joint spacing to wavelength ratio is smaller, the seismic wave transmission coefficient is small, the slope dynamic response characteristics affect larger, the ratio reached a critical value, transmission coefficient is the biggest and the slope dynamic response characteristics impact to a minimum.(6) Slope in the presence of different physical and mechanical properties of the lithological interface, if the lithology of the lower part of the interface is the upper lithology hard, with the increase of the two kinds of rock elastic modulus difference, peak acceleration of transmission wave reduce more obvious; otherwise when the interface following lithology is upper soft, with the increase of the two kinds of rock elastic modulus difference, peak acceleration of transmission wave amplification is more obvious; if the existence of weak intercalated layer, the thickness of soft interlayer and its surrounding rock wave impedance ratio is larger, the transmission effect is small when the seismic waves pass through the weak interlayer. |
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