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Abstract In order to accurately obtain the distribution rule of initial geostress field in Jiata dam area in West Route of South-to-North water transfer project，a new two-stage back analysis method of initial geostress field which considers the complex geological conditions and the ground denudation process is presented. Firstly，considering mainly the influence of topography，faults，folds，and development history of river valleys，a large-scale calculation model for the dam area is established. And the genetic neural network method as well as FLAC3D is applied to the first-stage back analysis of initial geostress field. Then，considering the main geological structures in the vicinity of the dam area，a small-scale refined model is created. The preliminary non-linear boundary conditions of the refined model can be obtained by fitting the stress values which are extracted from the large-scale model of the first-stage back analysis. After that，calculation for the second-stage back analysis of geostress field is conducted by optimizing the boundary parameters based on genetic neural network method. It is shown that the difference between the calculated results and the measured data is large in the vicinity of the local geological structures during the first-stage back analysis. And the calculated results are much closer to measured data in the second-stage back analysis by considering the small geological structures as well as the results in the first-stage back analysis. Therefore，the proposed method provides great reference to similar projects.
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Received: 21 May 2013
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2014, Vol. 33 
