Study On The Effect Mechanism Of Seismic Slope

The instability and damage of the rock slope under the earthquake are often very serious consequences, which can cause immeasurable loss to the country and the people.How to predict and evaluate the slope stability under the earthquake and reveal the dynamic response of the seismic slope instability mechanism is particularly important.Most of the researches on seismic geological hazards are based on the relationship between the distribution of earthquake disaster and earthquake magnitude, seismic intensity, slope height and slope angle. After the Wenchuan earthquake, the landslide geological hazard characteristics through statistical process has found that a large number of landslide obvious "back slope effect", namely the development of density was significantly greater than the head slope on one side of the back slope side of the seismic wave propagation of landslide. The back slope effect of slope sliding direction is generally through a lot of statistical investigation, qualitative analysis from the geology, the lack of research and Analysis on the formation mechanism of the quantitative, but generally consider the reflection, and seismic wave in the slope of the propagation of refraction, so from the propagation theory of seismic waves were analyzed on the back slope effect.Seismic slope failure is a static and dynamic part of the comprehensive effect, the research usually use static and dynamic finite element analysis, but the calculation precision is easily affected by the grid model, size and boundary, and cannot directly reflect effectively the dynamic mechanism of slope under earthquake. In this paper, the basic theory of seismic wave reflection and transmission theory and solid elastic mechanics based on the consideration of structural plane and slope caused by the wave field separation and superposition, the simplified calculate slope point in a dynamic stress instead of using dynamic finite element calculation of dynamic stress, and then the finite element calculation of gravity field the static stress combination, a new method for calculating the dynamic safety factor of time history is derived. Then the P wave and SV wave with different incident angles of rock slope and slope to a certain angle with different slope angles using this method, the theoretical method to calculate the dynamic variation with different incident angles and angle of slope stress. Finally, the dynamic stress of substitution (3-63)?(3-67), complete the calculation process of the dynamic safety factor,and gives the minimum (average) variation of dynamic safety coefficient with different incident angles, which reveals the back slope effect. Through the study to obtain specific results and understanding as follows:(1) For the same conditions of the slope and the slope, when the seismic wave at the same tilt angle of the incident, the angle of incidence and slope angle is different from the resulting power field is not the same, is caused by the back slope effect The main reason.(2) Due to the influence of the incident direction, the normal of the back slope and the incident wave form a small angle incident, and the normal and incident waves of the slope face are incident at a large angle, resulting in a vibration field on the back slope, The slope is more prone to instability than the slope.(3) For the P wave with inclined incident, the dynamic stress of the back slope is obviously larger than that of the slope, and the dynamic safety coefficient of the back slope is obviously smaller than that of the slope.(4) For the incident seismic wave, when the incident angle is about 40°?70°, the dynamic stress of the slope is larger than that of the earthquake under the same conditions,and the dynamic safety coefficient is stronger than that under the earthquake P wave The value is small.(5) For the seismic wave incident at 60 °,when the slope angle is about 50°?65°,the dynamic response of the slope is relatively large, and the dynamic response caused by SV wave is more obvious. The results of the survey are consistent.