Mechanism Of Instability And Calculating Method On Stability For Roadbed Along For The Rivers Bank In Mountainou Areas

In recent years, water resources and hydroelectric industry has flourished in China, a large number of bank roads were built and put into use. However, bank collapse, instability and deformation of bank roadbed often occurred. As a result, many experts and scholars paid a lot of attention to the stability of bank roadbed slope. Because the long-term impact on the bank roadbed by reservoir water, slope rock materials, hydrodynamic condition of water and mechanical performance changed frequently. Compared to the general roadbed, its instability mechanism has obvious differences under the interaction of multiple dynamic factors. In order to ensure better operation of reservoir-bank road and improve safety performance of the roadbed, it is necessary to carry on the study basing on the bank roadbed instability mechanism, factors resulting in destruction and deformation, and the calculation method and assessment of corresponding stability. This paper mainly conducted in the following aspects of work, on the basis of summing up the previous research.①On the basis of summing up several common destruction modes of bank slope, the geology and hydraulic power were analyzed systematically as the two main factors affecting the stability of roadbed. The mechanism of different hydraulic factors to bank slope by the action of underground water was studied. Analysis of reservoir-bank roadbed instability mechanism and studies on the causes and characteristics of roadbed instability deformation were carried on, the impact of seepage effect on bank roadbed slope stability was revealed.②The basic mode of seepage field in bank roadbed slope under the change of reservoir water level was studied. The mass conservation law was applied under the effect of dynamic and static water pressure, unsaturated soil seepage differential equations were established, relationship between permeable pressure and surrounding water pressure was worked out. The seepage force of element was applied to calculate the seepage-induced equivalent nodal forces, and the solution of the problem is more detailed and accurate.③With the derivation of stability formula in traditional slice method and the introduction of the concept of seepage force in calculation, stability formula was deduced, and the problem is more simplistic. The study on how safety factor was calculated by FEW was carried on, the calculated results was considered more reasonable and precise.④According to the analysis on calculation principle of strength reduction finite element method, with the introduction of PLAXIS numerical analysis program, combining specific calculation examples, numerical simulation on the stability of the bank roadbed slope under the effect of seepage during precipitation was carried on, the result was consistent with the actual situation.⑤The stability of bank roadbed slope under different situation was analyzed with the program PLAXIS. Different precipitation patterns and permeability coefficient of roadbed soil were analyzed by the calculation examples, the variation laws of changes of slope safety factor was summarized. At the same time, the impact on stability of roadbed slope of high excess pore water pressure was analyzed, it is considered as one unfavorable factor that should be paid attention to in the actual project in the future.