Study On Dynamic Response Rules And Deformation Failure Mechanism Of Bedding Rock Slope

The stability of rock slope with seismic action is a important problem which always comes forth and needs to be solved in the engineering construction, however, the study of deformation and failure mechanism about rock slope is the key to solve the problem of slope stability with seismic action.Bedding Consequent layer rock slope is the most common rock slope. Reach on deformation and failure mechanism can not only explain the slope instability mechanism, but also check the rationality and validity of present stability analysis method, and develop the base of new method and decreasing disaster.In the text, we firstly construe the dynamical respond and earthquake resistance design of rock slope at home and abroad, advance earthquake resistance design concept of slope based on seismic response spectrum based of much basic work. Lastly,we found an appropriate model of homogeneous and consequent layer rock slope and choose reasonable boundary conditions,by finit element numerical simulation, we analyze the factors and rules of natural vibration identity , dynamical response and the deformation and failure mechanism Judging from slope destroy in Wen Chuan earthquake and others, the distortion and demolish in earthquake always turn to be selective, which cannot be explained well by traditional calculate theory. This is because the dynamical effect of earthquake is described by amplitude, frequency spectrum and time. However, we designed the earthquake resistance of the rock slope by simulate static force before, which only considered amplitude and neglect the other two factors. So reaction frequency spectrum method is more reasonable in earthquake resistance design of the rock slope.It can consider amplitude and frequency spectrum and has been widely used in structure engineering. It will be used in slope engineering in the future, and the natural vibration period of rock slope is an important basic work.Firstly, relying on perpendicular test, we design and build many models of working conditions, and choose reasonable boundary range and element size. We get first ten natural vibration periods by finite element software. By statistical analysis methods, we also get the rule and estimate formula about the affect of slope height, slope angle, elastic modulus, Poisson's ratio and density to natural vibration period, which will be valuable in practice. From the result, we find that the natural vibration period of the rock slope computerized by finite element method has close relation with the calculation range and element size.And there is characteristic element size.(When the element size is smaller than characteristic element size, the computerized period of the rock slope will be stable.)Therefore, element size should be considered when we computerize the period of the slope with finite element method. When the characteristic element size is 2m, the computerized natural vibration period of the slope can be regarded as the accurate value.:The natural vibration period of the rock slope has positive correlation with slope height, slope angle, Poisson's ratio and desity, and negative correlation with elastic modulus. Slope height and elastic modulus have the greatest influence to the period of the rock slope. We advance a estimating formula about the natural vibration period of the rock slope. The estimating formula in this paper has been validated to be highly reliable, and it can be directly used to computerize the period of the rock slope.However, the estimate formula we advance here has its own boundaries, and it needs to be validated whether it can be used in other place.Then, by setting the weak layers that have different location, thickness and intensity, we analyze the influence of the slope height, the slope angle and the character of weak layer to the natural vibration period. Through clearing up and analyzing the data, we find that the natural vibration period of the consequent layer rock slope that contains weak layer is longer than that of the homogeneous rock slope. The natural vibration period of the consequent layer rock slope has a linear relationship with the slope height,that is, the natural vibration period of the rock slope increases as the increase of slope height. The natural vibration period of the rock slope have positive correlation with the slope angle, that is, the natural vibration period of the rock slope increases as the rising of slope angle, and the larger the slope angle is, the more significant impact by the weak layer. The closer to slope surface the weak layer is, the longer the vibration period is. As the augment of the weak layer increase, its impact becomes more significant. When the thickness of the weak layer surpasses 5 meters, the impaction of the weak layer on the vibration period has nothing to do with its thickness. The natural vibration period of consequent layer rock slope has a linear relationship with the thickness of the weak layer.The smaller the elastic modulus is, and the larger angle of the weak layer is, the impact of the weak layer's thickness on the vibration period is more significant. The natural vibration period of consequent layer rock slope has negative correlation with the elastic modulus,that is, the bigger the elastic modulus is, the smaller the period becomes. The thicker the weak layer is, the remarkable the effect of elastic modulus is. As a whole, the natural vibration period of the consequent layer rock slope decreases as the increase of the inclination of the weak layer. As the inclination of the weak layer lies between 40-60°,the vibration period changes slightly.The study of vibration period of consequent layer rock slope has reference to many factors. We only finish some simple work here, and haven't taken over joint and cranny, which requires to be studied in the future.At present, the study of dynamical character and earthquake respond calculation is only the dynamical calculation and earthquake resistance analysis by finite element of some special slopes, and the study cannot meet the need of practice now. So it's practical to construe some rules and reach general conclusions.This paper researches the general rule about how the slope height, slope angle, elastic modulus and Poisson's ratio of the homogeneous rock and consequent layer rock slope influence the horizontal dynamical magnifying coefficient and the slope responding peak. For the rock slope in the scale of 50m to 400m, alone with the increasing of the slope height, horizontal acceleration, velocity and the magnifying responding value of displacement will firstly increase and then decrease; the peak value of the horizontal acceleration and velocity will also increase alone with the increasing of slope height, then decrease, the peak value of the horizontal displacement will increase. The responding magnifying value of horizontal acceleration, velocity and displacement will generally increase alone with the increasing of slope angle, and has positive correlation with it. When the slope height is small, the peak value of the horizontal acceleration, velocity and displacement will gradually increase alone with the increasing of slope angle; when the slope height is big, the peak value of the horizontal acceleration, velocity and displacement will firstly increase alone with the increasing of slope angle, and then decrease, and gradually increase at last. Alone with the increasing of elastic modulus, the responding magnifying value of the horizontal acceleration, velocity and displacement will gradually increase, and begin to decrease when it is up to 10GPa. The responding magnifying value of the horizontal acceleration is the biggest, then is the velocity, the responding value of displacement is the smallest. However, on the contrary, the peak value of horizontal acceleration, velocity and displacement will firstly decrease and begin to increase when it is up to 10GPa; Generally, Alone with the increasing of Poisson's ratio, the responding magnifying value and peak value of the horizontal acceleration, velocity and displacement will gradually decrease. So, generally speaking, the influence of Poisson's ratio to dynamical respond rule is not large. It is similar with the rule of homogeneous slope that the way horizontal dynamical responding magnifying value and peak value change with slope height. Generally, the two values increase with the augment of slope height, but they are larger than that of homogeneous slope. Alone with the increase of slope angle, horizontal dynamical responding magnifying value also increase, which is the same as the rule of homogeneous slope. Alone with the increase of weak layer, horizontal acceleration responding magnifying value will decrease to some extent, but horizontal velocity and displacement responding magnifying values increase basically, and the three values reduce with the decrease of angle on the whole. The distance between weak layer and slope toe has little effect to horizontal dynamical responding magnifying value, and has negative correlation between each other. Nevertheless, the peak value of horizontal acceleration, velocity and displacement increase with the enhancement of the distance. Alone with the increasing of elastic modulus of weak layer, it reduces observably that the responding magnifying value and peak value of the horizontal acceleration, velocity and displacement, which is inverse ratio. With the augment of the thickness of weak layer, it increases slightly that the horizontal responding magnifying values of horizontal acceleration, velocity and displacement. Besides, the three peak values have positive correlation with the thickness of weak layer.In the paper, we reach the general rule of the influence of slope form, intensity and weak layer to the character of natural vibration, and supply definite base for dynamical analysis of slope and the calculation of earthquake resistance based on response spectrum method.By choosing certain typical bedding rock slope,this paper simulates the deformation and failure mechanism through finite element method. It is shown that the strength of the weak layer and the bedding surface are the key factors for deformation and failure of the slope. And Stress concentration is the basic reason .The extension of the plastic strain area can be seen as the process of the slope deformation...