Progressive failure mechanism of reinforced ground and its application to limit state design

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Design methods for earth reinforcement structures are mainly based on the limit equilibrium method which assumes the location and the shape of failure mechanism. In addition, in the current design method, it is assumed that the failure mechanism of the reinforced foundation ground is the same as that of non-reinforced foundation ground and the effect of reinforcing material is added in the design calculation in term of its tensile strength. Considering the future trend of the design method, it should be optimized from an economical point of view. This has been achieved by the development of "limit state design". Also, the new feasibility or application of this design should be the next target. For this purpose, it is necessary to investigate actual behavior of the reinforced foundation ground on both deformation and failure mechanism. According to the effect of earth reinforcement, it may be considered that the reinforcing effect is deeply related with the localization of deformation a … More nd progressive failure.The purpose of this research is to investigate the behavior of real progressive failure of the reinforced foundation ground and to establish a valid quantitative design calculation which could be based on the real failure mechanism. First of all, a series of model loading tests using the simulation of foundation ground by aluminum rods are conducted, in which the length and the property of the reinforcing material are varied. Based on the results of the loading tests, not only the bearing capacity but also the mechanism of progressive failure is investigated by using image processing analysis. Thus the progressive failure of the reinforced foundation ground are discussed in detail based on the microscopic observation and the analyzed results. These experimental results are concurrently analyzed by using "rigid-plastic finite element method". In the analysis, the model of reinforced soil is newly developed and also geometrical nonlinearity is taken into consideration in order to obtain the progressive behavior of the ground. The validity of the proposed method are verified by comparing with the results of the model tests. In addition, a simplified upper-bound mechanism appropriate to the observed mechanism is proposed, and applied to the test cases.The results achieved through this research are fundamental on the localization of deformation and progressive failure of the reinforced foundation ground. These results could be proved to be indispensable information for the future design method. Furthermore, the proposed analytical method for the reinforced foundation ground could have a great promise for the bearing capacity of reinforced earth structures. Less