| The anti-dip layered rock slope refers to the slope which has a strike parallel to the strike of strata and has an opposite dip with the strata. In terms of the structure of the slope, the anti-dip slope should belong to the most stable type. But with the human engineering activities have become more frequent and expansion of the scope, at home and abroad in terms of water conservancy and hydropower, mining, railways, urban environment disasters and so on there are a large number of anti-dip slopes unstable failure disastrous accident. This makes people gradually realized the necessity and urgency of the study of influencing factors and deformation mechanism for this widespread anti-dip rock slopes. Is generally believed that the anti-dip slope failure is due to bending and dumping deformation tensile failure of the rock layer. However, in the field survey observations, the leading edge of a large number of anti-dip slopes have shear failure phenomenon has been found. Figuring out how anti-dip slope failure surface is formed is the basis for the establishment of the anti-dip slope reasonable mechanical model, the rationality of the model directly affect the intergrality and correctness of the results of the follow-up study; Second, among the existing study of anti-dip slope factors influencing, there is only simple statistical analysis and qualitative description about the relationship of the influencing factors and the slope dumping deformation, but is not depth analysis of the causes of the statistical results. The analysis of influencing factors is the basis of the study of deformation mechanism, and its depth of analysis is directly related to the level of awareness of the anti-dip slope deformation mechanism.In view of this, on the basis of the current research status, By means of observed field phenomenon, plastic mechanics analysis and so on, this thesis proposed the view that the formation mechanism of the failure surface should be both bending crack and compression shear, and on this basis the cantilever beam limit equilibrium analysis model is established. Next, the anti-dip slope internal factors (strata dip angle, slope dip angle, slope height, thickness, interlaminar mechanical parameters, strata mechanical parameters) is selected as analysis objects, the analysis of influencing factors and the study of the Mechanism of the mechanical is done for the toppling deformation of homogeneous equal thick anti-dip layerd rock slope by the equilibrium analysis model and numerical model. and the research is applied to the instance which has some theoretical significance and application value.The main contents and results are as follows:(1) Study of the formation mechanism of anti-dip layered rock slope failure surface. on the basis of current research status, the thesis studies around the cantilever beam limit equilibrium model by means of the wild phenomenon of observation, elastic-plastic mechanics analysis and so on, concluded that the deformation geometric space differs in different parts of the slope, which determines the different failure mode in different parts of anti-dip slope. Following the failure surface can be considered fixed no distortion, above failure surface has different degrees of deformation. by means of setting the datum plane, constantly modify the position and shape of the reference plane based on mechanics analysis results, and finally can determine the location of the failure surface. Below the datum plane can be considered the deformed geometry space completely restricted, and stress concentration with increasing confining pressure; shear failure occurs at the datum plane, due to the local limited of the deformation geometric space; above the datum plane, when σ1≤1/2σO, the rock is only possible to occur tensile failure, when σ1>1/2σO, the rock is more likely to occur shear failure. Finally, the view that the formation mechanism of the failure surface is both bending crack and compression shear is proposed.(2) Study of homogeneous equal-thickness anti-dip layered rock slope mechanical analysis model, some reasonable assumptions are made on Additional bending moment, interlaminar stresses, friction between the layers and shear fracture angle, calculation models is established and example verified. The model calculation results show that: the damage zone can be divided into the slip area, dumping area and toppling deformation affected zone. Damage zone size is determined by the slope dip angle, strata dip angle, slope height. The damage zone exists when [α-(90°-β)-(45β-(?)/2-δ)]×h>0and so the failure may occur. Rock deformation driving force comes from the gravitational field, the gravity is only considered when simplify estimates; Interlaminar positive pressure is on control of rock failure modes; role of friction between the layers is to add a resistance bending moment, which cannot be ignored when the rock layer thick or interlaminar friction is large. The simplification of interlaminar stress leads to the situation that the shear failure depth above the datum plane do not exist (no solution) in most cases, which tells that this simplified is to meet the most situations, but there are some limitations.(3) Analysis of homogeneous equal-thickness anti-dip layered rock slope toppling deformation influencing factors. According to the designed analysis program, the affect of the internal factors (strata dip angle, slope dip angle, slope height, thickness, interlaminar mechanical parameters, strata mechanical parameters) to the anti-dip slope toppling deformation is analyzed using the established model. The results show that:As the strata dip angle increases, the top of the hill toppling deformation increases and the deformation affected area increases, toppling deformation difficulty degree presented difficult-easy-difficult, the interval (60,70) can be the advantage strata dip angle range, the bending is very small when strata dip angle less than30°or greater than85°; As the slope dip angle increases, toppling deformation increases, and the deformation affected area increases, toppling deformation difficulty degree is from hard to easy, the bending effect is very small when the slope dip angle is less than35°; As the slope height increases, the overall scale of the slope increases, toppling deformation increases, the deformation affected area increases, toppling deformation difficulty degree is from hard to easy; With the thickness, interlaminar mechanical parameters or strata mechanical parameters increases, the ability to resistance the toppling deformation enhances, toppling deformation affect depth increases, toppling deformation reduces, the deformation affected area increases, toppling deformation difficulty degree is from easy to difficult. As interlaminar mechanical parameters increases, the roll of layer cracks weakened and anti-dip slope integrity enhanced. As strata mechanical parameters increases, its tensile strength, shear strength, resistance to deformation ability is to improve, making the enhancement of their own ability to resistance the toppling deformation, but still affected by the interlayer fractures, deformation amount is larger when compared to the slope with the same shape and quality, and integrity is not good.(4) Case study of homogeneous equal-thickness anti-dip layered rock slope toppling deformation mechanism. Toppling deformation depends on the component force on the rock which is to produce bending deformation, the length of the possible bending rock and resistance to bending effects or flexural capacity. Internal factors such as strata dip angle, slope dip angle, slope height, thickness, interlaminar mechanical parameters, strata mechanical parameters and so on affect the toppling deformation by means of affecting the three variables above. The slope morphological characteristics (slope dip angle, slope height) only change the length of the bending rock. The strata dip angle determines the decomposition of the rock force (proportional) and possible bending rock length when the slope morphology is the same, which affect the toppling deformation of slope by means of affecting bending effect (torque value). The strata thickness determines the density of the rock fractures, and influences the bending moment. Interlaminar mechanical parameters determine the integrity of the slope, and determine the resistance to bending moment (bending effects) with the thickness of the rock. Strata mechanical parameters determined flexural capacity of the rock and the integrity of rock own, the capacity to resistance to deformation, tensile and shear of the rock itself is influenced. According to cantilever beam limit equilibrium model and toppling deformation mechanism, Xiaodongcao-zhengjiadagou band slope itself which is under the influence of external factors such as reservoir storage, as well as the slope excavation, has the basic conditions conducive to toppling deformation occurred, the slope deformation mechanism is that the toppling deformation at front of the slope is exacerbated by the two factors, which pulling the entire bank slope toppling deformation from front to back. By way of example, homogeneous equal-thickness anti-dip layered rock slope toppling deformation mechanism is to be proved useful and correct. |
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