Research On Models Of Landslide Stability Calculation And Dynamic Process Based On The Energy Conservation

Landslide research is recognized as a cutting-edge topic in the world, and its complexity and randomness give researchers a huge challenge, while attracting researchers for its continued exploration. In this paper, the two problems that landslide stability analysis and its movement process after damage are taken as the research targets, with the concept of conservation of energy as a starting point. Radial slice method is adopted to establish the analysis model. By assuming the virtual displacement, a mathematic model of the landslide stability calculation is established, and by deducing the equation of conservation of energy in the process of landslide movement, the landslide motion mathematical model is established. These two models are applied to engineering examples, which verified their rationality and applicability. The concrete research contents and the main research results are as follows:1)On the basis of landslide failure mode of "translation" and "rotation", the radial slice method is adopted to establish the physical analysis model of landslide stability calculation and motion process. Compared with vertical slice method for landslide with arc sliding surface, modeling method of radial slice is more in line with the "rotation" instability mode.2)Based on the thought of conservation of energy, using the modeling method of radial slice method, assuming a virtual displacement, the mathematic model of landslide stability calculation is established. Based on the virtual displacement ds, the gravitational potential energy change △U and the friction energy dissipation △W on sliding surface are deduced, the landslide stability coefficient is defined as Sc=△W/△U, finally, the mathematic expression of landslide stability coefficient Sc is obtained in two cases of considering groundwater and without considering groundwater. Through the example analysis, and comparing the calculation result with Janbu, the results show that, without considering the groundwater, calculation results of energy method and Janbu method is relatively close, and the former stability coefficient is slightly higher, the differential ratio is 0.19%; under the condition of considering the influence of groundwater, the differential ratio is 9.77%, the stability coefficient calculated by energy method is lower, namely, in the energy method, the influence of groundwater on landslide stability coefficient is greater. Based on example 1, the main parameters of the model are analyzed on the sensitivity of the stability coefficient of Sc.3)Based on the idea of conservation of energy, using the modeling method of radial slice method, the landslide energy conservation equation during its motion process is deduced, and the mathematical model of landslide post-failure motion is set up. In the process of landslide movement, mutual conversion happens between gravitational potential energy, kinetic energy, friction energy, and the total energy keeps conservation, so as to establish the equation of conservation of energy, with the help of MATLAB software to solve the equation. By designing two landslide movement numerical examples, and comparing with methods of Panjiazheng and discrete element which are widely applicated in landslide movement simulation, the results show that the motion duration of energy method is relatively close to Panjiazheng method, less than the discrete element method; The total sliding distance of energy method and discrete element method is more close, more than Panjiazheng method; the peak displacement rate of energy method in three methods is the largest, followed by Panjiazheng method, the discrete element method is minimal.4)The landslide stability calculation model and dynamic model based on the energy conservation, which established in this paper, is applied to the engineering examples, and the rationality and applicability of the models have been verified. Take the Lidongcun landslide which failured in November 2015 in Lishui city, ZheJiang province as the first engineering example, which represents the rainfall as the main trigger factor of highway landslide. The results of stability calculation and movement process calculation can better reflect the actual situation of this landslide. Take the Qianjiangping landslide which failured in June 2015 in Zigui county as the second engineering example, which represents the reservoir water level variation as the main trigger factor of reservoir landslide. The results of stability calculation and movement process calculation can also better reflect the actual situation of this landslide.5)The landslide stability calculation model and dynamic model based on energy method have certain advantages over other methods. From the perspective of modeling method, for the landslides with arc sliding surface, radial slice of energy method is more suitable than vertical slice for landslide slip-rotating movement patterns. From the point of research method, energy method puts slider as the research unit, from micro to macro, computing the energy change internal the whole system, establishing the energy conservation equation to control the whole movement process of landslide, avoid the complex mechanical calculation process between sliders. Finally from the results of all examples, the energy method is more reasonable for application in the landslides with arc sliding surface.