Development of Crack Initiation Algorithm in Crack Analysis of Rock Mass by Element Free-Galerkin Method

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Pornkasem Jongpradist Ekarat Silabampen Apiwish Thongraksa Jukkrawut Tunsakul


The element free-Galerkin (EFG) method has been continuously developed for crack propagation analysis.       Previous researches focus on comparing the accuracy of the propagation direction with the results of the experiment in laboratory of which the crack initiation can be well specified. Thus, the attention on crack initiation prediction has been ignored. This becomes the drawback of implementation of EFG in full-scale engineering problem, particularly in the field of geotechnical engineering which the crack initiation point generally cannot be predetermined. This research aims to develop the algorithms for assessing the initial point of failure to be equipped with the EFG method. The development is based on tensile failure criterion under plane strain condition. The developed algorithm is verified  and validated by the failure behavior of rock mass surrounding a gas storage circular tunnel under high internal pressure problem. The in-situ stress ratio of 0.5, 1 and 3 are considered in the study. The analysis results can thus be compared with the existing results of analytical solutions and physical model tests. The comparisons show that the crack initiation points from the prediction using the developed algorithm have good agreement with the close form solutions and the experiments. Moreover, with a series of parametric study, not only the effect of in-situ stress condition, but also those of the depth and rock tensile strength can be simulated by the method developed in this study. The algorithm developed is therefore acceptable.


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